blood and lymph2 Flashcards
(160 cards)
1
Q
HEMATOLOGIC MALIGNANCIES
A
These disease share in common the fact that they represent clonal populations of malignant cells arising from a transformed cell of marrow derivation, regardless of whether the actual transformation took place in the marrow, in a lymph node, or elsewhere. Thus these can include neoplasms of immature hematopoietic cells (blasts), lymphocytes, granulocytes, or any other marrow-derived cell, common or rare.
2
Q
hronic lymphocytic leukemia (CLL) / small lymphocytic lymphoma (SLL)
A
CLL and SLL are the same biologic disease, the difference between the terms being whether the disease is primarily involving the blood and marrow (CLL), or primarily present as enlarged lymph nodes due to solid growth (SLL). In many cases, both manifestations might be prominent, and the term “CLL/SLL” can be used.
3
Q
CATEGORIES OF IMMUNODEFICIENCY STATES
A
Immunodeficiency can be primary or secondary. Primary immunodeficiency means a disease with a genetic cause, while secondary implies that some known process outside the immune system has caused the immunodeficiency. If the thymus or bone marrow were congenitally dysfunctional that would result in primary immunodeficiency, while the immunodeficiency that follows treatment with immunosuppressive drugs, or that is seen in patients with advanced cancer, or AIDS, is secondary to those conditions. Another way of putting it is that immunodeficiency can be congenital or acquired, depending upon whether the condition existed at birth or not. Acquired immunodeficiency will usually be secondary to some other condition. Immunodeficiency can also be temporary and self-limited, as in the transient hypogammaglobulinemia of infancy, or during treatment with cancer chemotherapy drugs; or it can be permanent.
4
Q
22q11.2 deletion syndrome
A
which has several presentations including DiGeorge syndrome (DGS), DiGeorge anomaly, velocardiofacial syndrome, Shprintzen syndrome, conotruncal anomaly face syndrome, Strong syndrome, congenital thymic aplasia, and thymic hypoplasia, is a syndrome caused by the deletion of a small piece of chromosome 22.
5
Q
Ataxia Telangiectasia
A
an autosomal recessive disease characterized by sinus infections and pneumonia, ataxia (staggering) and telangiectasia (dilated abnormal blood vessels). There is both T and B cell deficiency, not absolute; IgA is especially depressed. There is also an interesting defect in DNA repair which may partially explain the extraordinary incidence of tumors in these patients.
6
Q
Wiskott-Aldrich syndrome
A
comprised of platelet and B cell deficiency, eczema, and many bacterial infections. It is X-linked.
7
Q
SECONDARY IMMUNODEFICIENCY
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Clinicians need to keep in mind that some of the treatments they administer will be toxic to the immune system and that some diseases will themselves be immunosuppressive. Drugs used in the therapy of autoimmune and inflammatory conditions, such as corticosteroids and some of the new monoclonal antibodies, can be profoundly suppressive, and patients treated with these drugs should be warned to keep away from people with infectious diseases (chicken pox, for example, can be devastating in an immunosuppressed person). Many viral illnesses, especially measles, mononucleosis, and cytomegalovirus (CMV) infection, are immunosuppressive, and secondary infection is common. Acquired Immune Deficiency Syndrome or AIDS is the most serious condition involving secondary immunodeficiency.
8
Q
ETIOLOGY OF HEMATOLOGIC MALIGNANCIES
A
The transformation of a hematopoietic cell to a malignant cell is thought to require multiple genomic insults – this is true even in cases where a single genetic abnormality might define the disease. These genomic insults might be chromosomal abnormalities demonstrable by cytogenetic studies, such as karyotyping and/or FISH, but many of the findings now coming to light, such as point mutations and internal tandem duplications, require molecular testing, such as PCR, to detect. The continuing detection of more and more genetic abnormalities associated with different heme malignancies allows continued development of prognostic stratification and specific therapies for these disease. Chromosomal abnormalities are detectable in a large majority of heme malignancies; recurrent abnormalities are most commonly balanced translocations. Many of these abnormalities are persistently seen in certain heme malignancies, such as the t(9;22) in CML. The persistence of these abnormalities allows their use as diagnostic markers for certain heme malignancies. Translocations are found frequently in both lymphoid and myeloid malignancies
9
Q
type I immunopathological disease
A
Symptoms or pathology due to IgE antibody. Since the type of B-cell-helper Tfh cell that drives switching to IgE seems to be closely related to the Th2 cell, Th2-mediated events are often seen along with those caused by IgE.
10
Q
type II immunopathological disease
A
Pathology due to IgG, IgM, or IgA antibody causing harm to self. In most cases this refers to autoantibodies. In the original Gell and Coombs classification, Type V was separate; but it is now folded into Type II, as it involves autoreactive antibody against surface receptors which happen to stimulate (rather than damage) the cell. This form of immunopathology is due to the actions of antibodies directed against a specific target tissue, cell, or molecule; so it is one of the forms of AUTOIMMUNITY. There is also T cell-mediated autoimmunity, which is a part of Type IV immunopathology. Note that it’s technically a lot easier to detect specific autoantibodies than autoreactive T cells. Type III immunopathology may also be due to self-reactive antibodies, but the manifestation there is immune complex disease.
11
Q
type III immunopathological disease
A
Pathology caused by the formation of immune complexes which are trapped in the basement membranes of blood vessels and activate complement, leading to vasculitic inflammation. When Type III is chronic, T cell-mediated immunity tends to become increasingly important as part of the disease.
12
Q
type IV immunopathological disease
A
Pathologic outcomes of normal or abnormal (including autoimmune) T cell responses, including both helper and cytotoxic cells.
13
Q
Chronic frustrated immune responses
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It refers to conditions in which the body is using the adaptive immune response to try to get rid of antigens that it never can. These include things like normal gut flora (as in Crohn disease), skin flora (psoriasis), chemicals (as in chronic beryllium disease), or foods (gluten in celiac disease). Some have used the deeply meaningless term ‘autoinflammatory diseases’ for these. In CFIR the antigen can be neither disposed of nor effectively walled off.
14
Q
Complement-mediated damage
A
issues against which antibodies are made can be damaged by lysis (red cells in autoimmune hemolytic anemia), by phagocytosis (platelets in autoimmune thrombocytopenic purpura) or by release of the phagocytes’ lysosomal enzymes and reactive oxygen species (probable in myasthenia gravis and Goodpasture disease).
15
Q
Stimulatory hypersensitivity tissue damage
A
If the autoantibody happens to be directed against a cell- surface receptor, it may behave as an agonist, mimicking whatever hormone or factor normally works at that receptor. The classic example of this is the ‘long-acting thyroid stimulator’ found in the blood of most patients with hyperthyroidism. LATS, as it was called for a long time, is simply an IgG antibody to the TSH (thyroid-stimulating hormone) receptor on thyroid cells; when it binds to these receptors, it mimics TSH and causes the cell to secrete thyroid hormones. Of course, the normal feedback controls won’t work in this case, so the result is hyperthyroidism, or Graves disease.
16
Q
Poststreptococcal glomerulonephritis
A
disorder of the glomeruli (glomerulonephritis), or small blood vessels in the kidneys. It is a common complication of bacterial infections, typically skin infection by Streptococcus bacteria types 12,4 and 1 (impetigo) but also after streptococcal pharyngitis. The exact pathology remains unclear, but it is believed to be type III hypersensitivity reaction. Immune complexes (antigen-antibody complexes formed during an infection) become lodged in the mesangium and glomerular basement membrane below the podocyte foot processes. This creates a lumpy bumpy appearance on light microscopy and subepithelial humps on electron microscopy. Complement activation leads to destruction of the basement membrane. It has also been proposed that specific antigens from certain nephrotoxic streptococcal infections have a high affinity for basement membrane proteins, giving rise to particularly severe, long lasting antibody response.
17
Q
Intravenous immunoglobulin (IVIG)
A
a blood product administered intravenously. It contains the pooled, polyvalent, IgG antibodies extracted from the plasma of over one thousand blood donors. IVIG’s effects last between 2 weeks and 3 months. It is mainly used as treatment in four major disease categories: Primary Immune deficiencies such as X-linked agammaglobulinemia (XLA), Common variable immunodeficiency (CVID) and hypogammaglobulinemia. Acquired compromised immunity conditions (secondary immune deficiencies) featuring low antibody levels. Autoimmune diseases, e.g. immune thrombocytopenia, and inflammatory diseases, e.g. Kawasaki disease. Acute infections. The precise mechanism by which IVIG suppresses harmful inflammation has not been definitively established but is believed to involve the inhibitory Fc receptor. However, the actual primary target(s) of IVIG in autoimmune disease are still unclear. IVIG may work via a multi-step model where the injected IVIG first forms a type of immune complex in the patient. Once these immune complexes are formed, they interact with activating Fc receptors on dendritic cells which then mediate anti-inflammatory effects helping to reduce the severity of the autoimmune disease or inflammatory state. Additionally, the donor antibody may bind directly with the abnormal host antibody, stimulating its removal. Alternatively, the massive quantity of antibody may stimulate the host’s complement system, leading to enhanced removal of all antibodies, including the harmful ones. IVIG also blocks the antibody receptors on immune cells (macrophages), leading to decreased damage by these cells, or regulation of macrophage phagocytosis. IVIG may also regulate the immune response by reacting with a number of membrane receptors on T cells, B cells, and monocytes that are pertinent to autoreactivity and induction of tolerance to self. Recent studies on T cell regulatory epitopes, Tregtiopes, might explain some of the tolerogenic and regulatory effects of IVIG.
18
Q
bioidentification of staph
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Assignment of a strain to the genus Staphylococcus requires it to be a Gram-positive coccus that forms clusters, produces catalase, has an appropriate cell wall structure (including peptidoglycan type and teichoic acid presence) and G + C content of DNA in a range of 30–40 mol%.
19
Q
Leukemia
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malignancy of hematopoitic cells, chief manifestation is of the blood and marrow (interconnected compartments).
20
Q
Lymphoma
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A malignancy of hematopoietic cells, derived from lymphocytes or their precursors, which presents primarily as a solid mass. A lymphocyte in peripheral lymphoid tissues for most lymphomas. Lymphomas may be nodal (presenting as enlarged lymph node(s)) or extranodal (presenting at sites such as skin, brain, or GI tract), or both.
21
Q
Extramedullary myeloid tumor (aka granulocytic sarcoma)
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A malignancy of hematopoietic cells, derived from myeloid cells or their precursors (granulocytes, monocytes, etc.), which presents primarily as a solid mass. Are not as common.
22
Q
Grade
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clinical aggressiveness of a malignancy, related to its growth rate, with higher grades being more aggressive/ more rapidly growing. Generally hematologic malignancies are categorized as either high grade or low grade.
23
Q
Acute vs. chronic leukemia
A
acute is used for high grade and chronic is used for low grade. A high grade, or acute, leukemia might present as a very high white blood cell count with near replacement of all normal cells in the marrow. They arise suddenly and is rapidly progressing, will have low platelets, low neutrophils (fever), low RBC. It is a very urgent disease. Caused when one lineage of cells, often blasts, accumulating due to black in maturation. A low grade, or chronic, leukemia may have very subtle symptoms, but very often is noticed incidentally on the results of a CBC performed for some other reason. CLL and CML. Usually increased WBC due to accumulation of normal mature cells. Catural course of disease is prolonged with small risk of transformation to higher grade.
24
Q
High grade vs. low grade lymphoma
A
high grade may present as a rapidly enlarging mass. Low grade may be a mildly enlarged nick lymph that hard been present for years ir as a mild degree of lymphadenopathy (enlarged lymph nodes).
25
Recall the biological reason that many lymphomas contain balanced translocations involving the immunoglobulin and T cell receptor genes.
During the initial immunoglobulin/ T-cell receptor rearrangement, during the maturation of b cells/t cells, and during the class recombination and somatic hypermutation process during activation of B cells cause genomic instability and frequent acuquisition of translocations.
26
Relate the importance of specific recurrent translocations in certain hematologic malignancies in regard to the clinical care of patients.
Chromosomal translocations are often seen in hematologic malignancies (e.g t(9;22) with CML). This type of finding is important because 1) their persistent presence allows them to be used as diagnostic markers for certain malignancies and 2) they place a critical role in the development of malignancy that they are associated with. Translocations are found in both lymphomas and myeloid neoplasms. This is thought to be due to the natural suseptability of genome to translocations during normal periods of genomic instability.
27
Epstein-Barr virus (EBV):
Can affect and transform B cells. Some cases of classical Hodgkin lymphoma, some cases of Burkitt lymphoma, some other B cell non-Hodgkin lymphomas
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Human T cell leukemia virus-1 (HTLV-1):
Causative factor in adult T cell leukemia/lymphoma (ATLL)
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Kaposi sarcoma herpesvirus/Human herpesvirus-8 (KSV/HHV-8):
Primary effusion lymphoma
30
Other predisposing conditions lymphoma include
primary or acquired immunodeficiencies, inherited conditions of genomic instability (Fanconi Anemia and ataxia telangiectasia), ionizing radiation exposure, exposure to certain DNA- damaging chemotherapies
31
Contrast the incedences of leukemia and lymphoma in adult populations versus childhood populations.
Leukemia is the most common childhood cancer by type. Lymphoma is the third most common childhood cancer by type. Children often get high grade malignancies, which corresponds to a higher cure rate.
32
Myeloid malignancies
are those arising from mature or immature members of the granulocytic, monocytic, erythroid, megakaryocytic, and mast cell lineages.
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Lymphoid malignancies
are those arising from mature or immature members of the B cell, T cell, and NK cells lineages.
34
Other hematologic maligancies
Histiocytosis, histiocytic sarcoma, dendritic cell tumor, and dendritic cell sarcoma are terms referring to malignancies arising from histiocytes and dendritic cells. These are extremely rare and will not be discussed further.
35
WHO classification system of tumors of haematopoietic and lymphoid tissue
diagnostic is based on microscopic appearance, of the malignant cells, histologic growth pattern of the malignant cells in the marrow, lymph node or other tissue, presence or absence of specific cytogenetic findings or molecular findings, relative amount of malignant cells present in the blood or marrow, presence or absence of certain cell surface markers/ cytoplasmic markers/ nuclear markers. A certain type of data may be a requirement for the diagnosis of a certain heme malignancy, but not have much bearing in making the diagnosis of other heme malignancies.
36
Acute leukemias
are usually due to the rapid accumulation of (usually) immature cells in the marrow. These immature cells often replace many of the normal marrow cells, resulting in cytopenias. Often, but not always, the immature cell is the generic- appearing blast. The large majority of acute leukemias can be classified as Acute Myeloid Leukemia (AML) or Acute Lymphoblastic Leukemia (ALL). rapidly growing malignancy, usually with a block in maturation resulting in the accumulation of immature cells in the marrow, often replacing normal marrow cells, and often accumulating in the blood as well. The immature cells are often, but not always, blasts; they can be myeloid or lymphoid.
37
Tools for evaluating acute leukemias include
Morphology - Sometimes it is obvious by appearance that the acute leukemia cells have a certain line of differentiation (monocytic, megakaryocytic), allowing for a diagnosis.
Immunophenotyping - This refers to the use of antibodies to detect whether certain substances are being expressed by cells. In the case of acute leukemia, we can do this by flow cytometry and immunohistochemistry. This allows us to place morphologically non-distinct cells, such as blasts, into a definite lineage (e.g. precursor B cell, myeloblast, etc.)
38
Myelodysplastic syndrome (MDS):
a group of conditions where a clonal population derived from a neoplastic hematopoietic stem cell takes over the marrow, and is not capable of making normal blood cells in one or more lineages (dysplasia). This disease is categorized in most cases by falling peripheral blood cell counts. Although many people regard MDS as a precursor to acute myeloid leukemia (AML), due to the high rate of progression from MDS to AML, MDS is arguably a malignancy in its own right, as many people die of MDS without progressing to acute leukemia, due to the failure of the marrow to make normal blood cells. In MDS you have not yet acquired a complete block in maturation. Rare. With low grade just to surveillance.
39
Myeloproliferative neoplasms (MPNs):
are neoplastic clonal proliferations of the marrow where the clone makes normal functioning blood cells, usually in multiple lineages, but makes too many of them in one or more lineages. MPNs are classified into different types based on the underlying cytogenetic abnormality, the types of blood cell(s) being overproduced, and other data. MPNs also have a tendency to progress to acute leukemia, though this tendency in much less than for MDS.
40
Classical Hodgkin lymphoma (CHL):
a very distinct clinical entity, driven by Hodgkin-Reed-Sternberg (HRS) cells. HRS cells derive from B cells, but the disease is its own unique clinical entity, due to its unique natural course and unique treatment regimens.
41
Non-hodgkin lymphoma
any malignancy derived from mature B cells (excluding CHL or plasma cell neoplasms), T cells, or NK cells. The large majority are derived from B cells.
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Plasma cell neoplasms
includes MGUS, plasmacytoma, and multiple myeloma.
43
Acute leukemia
a clonal, neoplastic proliferation of immature myeloid or lymphoid cells.
There are two major categories of acute leukemia: acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL).
Immature leukemic cells which are unable to differentiate/mature beyond a very early, usually blastic, precursor stage, accumulate in the bone marrow, displacing normal hematopoietic elements. It is the loss of normal hematopoietic elements, and subsequently normal peripheral blood cells that causes the signs and symptoms of acute leukemia. Acute leukemia is rapidly fatal without treatment. There must be a block in ability to differentiate and increased autonomy of growth signaling pathways outgrowing normal cells
44
Acute myeloid leukemia
the genetic perturbations that cause AML occur at the level of the pluripotential stem cell or one of the committed progenitors. Progenitor cells committed to all of the several different paths of myeloid differentiation may be involved in leukemogenesis. There are therefore different types of AML stemming from different types of myeloid cells (granulocytic, monocytic, erythroid, and megakaryocytic). AML is a very heterogeneous disease, morphologically and clinically, and may involve one or more or all myeloid lineages.
45
Acute lymphoblastic leukemia (ALL):
malignancies of precursor lymphoid cells less commonly occur as solid masses (lymphoblastic lymphoma, LBL). ALL is divided into B-lymphoblastic ALL (B-ALL) and T-lymphoblastic ALL (T-ALL). Incidenc is between 1 and 5 cases per 100,000 persons per year (about 3,000 new cases per year in US). 75% of cases of ALL occur in children less than 6 years old.
46
ALL diagnosis
ALL patients nearly always present with blasts representing a majority of marrow cells (“packed marrow”); thus, there is no set percentage of blasts required to diagnosis ALL. Peripheral blood white blood cell count may be markedly increased, mildly increased, normal, or decreased (cant get out of marrow). Determination of blast type (myeloblast vs. lymphoblast, as well as B-lymphoblast vs.T-lymphoblast ) requires immunophenotyping. Generic markers of immaturity (also on myeloblasts) include CD34. Common lymphoblast marker (not on mature lymphocytes) include TdT. Markers of B cell lineage include CD19 and CD 22. Marker of T cell lineage include CD3 and CD7.
47
ALL prognosis
ALL is generally a good prognosis disease in children. In children, the complete remission rate following chemotherapy is greater than 95%, with cure rates of around 80%.
In adults, ALL is a worse disease, with complete remission rates of 60-80%, and cure rates of less than 50%. Age: worse prognosis for infants (10 years) or adults. White blood cell count: worse prognosis if markedly elevated white blood cell count at time of diagnosis.
Slow response to therapy / small amounts of residual disease after therapy: worse prognosis if either of these occurs. Number of chromosomes: very favorable prognosis for hyperdiploidy (>50 but <46 chromosomes).
B versus T lineage: Even when attempting to control for other factors, such as age and white blood cell count, T-ALL seems to have a worse prognosis than B-ALL.
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Acute myeloid leukemia (AML) incidence
Worldwide incidence of around 3 cases per 100, 000 persons per year
Average age at diagnosis: 65 years old
Rare in children and young adults (AML only accounts for around 10% of childhood leukemia)
49
AML diagnosis
The diagnosis of AML is usually based on the identifications of increased myeloblasts accounting for 20% or more of nucleated cells in the marrow or peripheral blood. This diagnosis can be made by microscopic review of bone marrow aspirate smears or peripheral blood smears, or by flow cytometric review of marrow aspirate material or peripheral blood, or by microscopic (and possibly immunohistochemical) review of the marrow core biopsy. There are other, rarer ways, not worthy for discussion here, by which the diagnosis of AML can be established. An exception to the requirement for 20% myeloblasts for the diagnosis of AML occurs if one can document the presence of certain recurrent cytogenetic findings.
50
Identifying myeloblasts for AML diagnosis
By flow cytometry, myeloblasts often express CD34, a generic marker of immaturity that can also be seen in lymphoblasts.
Myeloblasts also often express myeloid antigens, such as CD117 (C-Kit) and myeloperoxidase, that allow them to be identified as myeloblasts (not usually on lymphoblasts). Some cases of AML show monocytic differentiation, and thus the leukemic cells may express monocytic antigens instead of typical myeloblast antigens.
Some cases of AML show megakaryoblastic differentiation, and thus the leukemic cells may express megakaryocytic antigens. Should be negative for lymphoblasts markers. Using a combination of flow cytometry, immunohistochemistry, and/or morphology, most cases of acute leukemia can be classified as either ALL or AML. In addition, the presence of certain recurrent cytogenetic abnormalities (usually translocations) allows a diagnosis of AML to be made regardless of the blast count
51
Explain the concept of a "leukemic stem cell".
Recently the existence of leukemic stem cells have been proven, which have potential for self-renewal. In patients with acute leukemia there is a population of cells that provide an inexhaustible source of leukemic cells that replace the bone marrow.
52
Risk factors for acute leukemia
are associated with conditions and agents that cause genomic damage/instability. However, many lack previous chemotherapy (especially DNA alkylating agents and topoisomerase-II inhibitors), tobacco smoke, ionizing radiation, benzene exposure, and genetic sydromes inlcudding down syndrome, bloom syndrome, fanconi anemia, and ataxia- telangiectasia.
53
Signs and symptoms of acute leukemia
they are related to decreased numbers of normal peripheral blood cells due to marrow infiltration by leukemic cells. Symptoms include fatigue, malaise, dyspnea, easy bruisability, weight loss, bone pain or abdominal pain (less common), nerologic symptoms (rare). Signs include anemia and pallor, thrombocytopenia, hemorrhage, exxhymosis, petechiae, fundal hemorrhage, fever and infection (pneumonia, sepsis, perirectal abscess), adenopathy, hepatosplenomegaly, mediastinal mass, gum or skin infiltration (rare), renal enlargement and insufficiency (rare), and cranial neuropathy (rare). Sometimes (rarely) patients present with very high white blood cell counts, the leukemic cells themselves may cause hyperviscosity (leukostasis) or thrombotic problems (DIC). In these instances, a pheresis machine may be used to selectively remove white blood cells from the blood (leukopheresis).
54
ALL diagnosis
Unlike AML, there is not a set percentage of lymphoblasts required to make a diagnosis of ALL. This is rarely a germane question, though nrealy all ALL patients present with near replacement of their marrow by lymphoblasts. Lymphoblasts (both B or T) tend to be smaller than myeloblasts. However, definitive identification of a blast as a lymphoblast, and assignment of B or T lineage, requires some type of immunophenotyping. Peripheral white blood cell count (WBC) may be markedly increased, normal, or decreased. Lymphoblasts often express CD34, a marker of immaturity also often expressed by myeloblasts. Lymphoblasts express TdT, a nuclear enzyme that is specific to lymphoblasts (i.e. not usually expressed by myeloblasts). TdT is also not expressed by mature lymphocytes.
55
cytogenetic testing to tell t-ALL and b-ALL
AML with recurrent cytogenetic abnormalities are entities where the presence of certain genetic finding in AML predicts a certain biological course, making a unique diagnostic entity. These cytogenetic abnormalities are typically balanced translocations, and may be detected by: cytogenetic analysis (karyotyping - less sensitive; and FISH - more sensitive) and molecular analysis (RT-PCR of mRNA transcript of fused genes - very sensitive)
56
B-lymphoblastic ALL (B-ALL):
accounts for majority (80-85%) of cases of ALL. B-lymphoblasts express B-lineage antigens (e.g. CD19, CD22, and/or CD79a).
B-lymphoblasts usually do not express markers of mature B cells, such CD20 or surface immunoglobulin (kappa lambda). B-ALL is the typical ALL of childhood.
57
T-lymphoblasts ALL (T-ALL):
T-ALL accounts for a minority of ALL cases (25-30%)
In contrast to B-ALL, T-ALL more frequently occurs in adolescents and young adults than in children and favors males over females.
In contrast to B-ALL, T-ALL more frequently present with a component of lymphoblastic lymphoma (T-LBL), often manifesting as a large mediastinal mass.
If the disease does have leukemic (T-ALL) component, the disease is more likely to present with a high white blood cell count than B-ALL.
T-ALL / T-LBL favors males over females.
T-lymphoblasts express T-lineage antigens CD2, CD3, and/or CD7. They may express both CD4 and CD8 concurrently, or may express just one or neither of these. They often express T-lineage antigens only seen in immature T cells, such as CD99 and CD1a.
58
B-ALL with t(9;22)(q34;q11.2); BCR-ABL1:
25% of cases of adult B-ALL (but only 2% of childhood B-ALL) contain a t(9;22) resulting in the Philadelphia chromosome, similar to what is seen in chronic myelogenous leukemia (CML). In these cases of Ph+ B-ALL, the BCR-ABL fusion protein differs from that typically seen in CML, in that it is only 190kd (p190) (instead of the 210 kd fusion protein seen in CML). This is due to the use of a different breakpoint in the BCR gene in ALL than in CML.
In both adults and children, Ph+ ALL has the worst prognosis of any subtype of ALL.
59
B-ALL with translocations of 11q23; MLL
:
B-ALL with abnormalities of MLL is frequently seen in B-ALL in neonates and young infants. These have a poor prognosis, and the frequency of this finding is the reason for the generally poor outcome of neonatal ALL.
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B-ALL with t(12;21)(p13;q22); ETV6-RUNX1
This finding is seen in 25% of cases of childhood B-ALL.
| Like AMLs with translocations of RUNX1 (see below), these cases of ALL have a very favorable prognosis.
61
List 5 factors affecting prognosis in ALL
Age- children usually have good prognosis complete remission rates >95%. In adults complete remission rates 60-80%. Infants less than one year usualy have t(9;22) is common and wrose prognosis. B-ALL have better prognosis than T-ALL. Very high WBC, slow response to Rx, and minimal residual disease have worse prognosis.
62
Auer rod
The typical morphologic appearance of a myeloblast is generic, and these cannot be reliably told apart from lymphoblasts by morphology alone, unless one sees an auer rod. Auer rods are fused azurophilic granules forming small stick-like structures in the cytoplasm. The presence of Auer rods allows the identification of a blast as a myeloblast. Furthermore, they are only seen in abnormal myeloblasts.
63
AML with t(8;21)(q22;q22); RUNX1-RUNX1T1
Found in about 5% of AML cases; seen in younger patients
Associated with "AML with maturation," i.e. some neutrophil production is still present at diagnosis
RUNX1 encodes alpha unit of core binding factor (CBF), a transcription factor needed for hematopoiesis. The fusion protein blocks transcription of CBF-dependent genes, thus blocking differentiation.
This AML has a relatively good prognosis.
The presence of this translocation is diagnostic of AML regardless of the blast count.
64
AML with inv(16)(p13.1;q22) or t(16;16)(p13.1;q22); CBFB-MYH11
Found in about 5%-10% of AML cases; seen in younger patients
Notable for the frequent presence in the marrow of immature eosinophils with abnormal basophilic granules in addition to their eosinophilic granules, so-called "baso eos."
Usually see a mixture of increased myeloblasts and increased monocytes, thus a "myelomonocytic leukemia."
CBFB encodes the beta subunit of core binding factor (CBF), thus mechanism of leukemogenesis is similar to above AML with t(8;21).
Also similar to AML with t(8;21), has a relatively good prognosis.
The presence of this inversion or translocation is diagnostic of AML regardless of the blast count.
65
Acute promyelocytic leukemia with t(15;17)(q22;q12); PML-RARA
Acute promyelocytic leukemia (APL) is a distinct subtype of AML in which abnormal promyelocytes predominate instead of blasts. Thus, most APL could, in prior times, be diagnosed based on the morphologic appearance of the leukemic cells.
APL accounts for around 5-10% of cases of AML
Now it is known that all APL cases have a recurrent t(15;17), which makes the diagnosis more accurate, as not all variants of APL have cells that morphologically resemble promyelocytes.
Typical morphology is hypergranular; cells resemble normal promyelocytes with abundant granules that often obscure the nucleus. May see cells with multiple Auer rods, so-called 'faggot cells' (from the definition of faggot meaning a bundle of sticks, not a derogatory usage).
The presence of t(15;17) is diagnostic of APL regardless of the blast/promyelocyte count.
APL is sometimes referred to as the M3 type of AML, which is based on a prior classification system and should thus no longer be used (but is still frequently used).
66
AML with t(1;22)(p13;q13); RBM15-MKL1
AML with t(1;22) usually shows megakaryoblastic differentiation, and is most often seen in infants with Down syndrome.
Relatively good prognosis with intensive chemotherapy (relative to other infantile acute leukemias).
67
AML with abnormalities of 11q23; MLL
The MLL gene at 11q23 may be fused with multiple different partner genes.
AMLs with a translocation involving MLL frequently show some degree of monocytic differentiation. AMLs with a translocation involving MLL have a poor prognosis.
68
APL is important to recognize for two reasons
1) The gene fusion in APL fuses the retinoic acid receptor-alpha (RARA) gene to another gene. RARA is needed for differentiation of promyelocytes; the fused product does not work well and leads to a block in differentiation. However, the block can be overcome with supra-physiologic doses of all-trans retinoic acid (ATRA), in combination with arsenic salts. Thus, these patients can be treated with ATRA/arsenic, and do not require traditional induction chemotherapy, which would be used for most AMLs. This is important as traditional induction chemotherapy has much higher rates of morbidity and mortality than ATRA therapy. With ATRA/arsenic therapy, APL still has better remission rates than any other type of AML. 2) Some cases of APL give rise to disseminated intravascular coagulation (DIC). Thus, it is important to recognize APL so that the clinician may know to be on the look-out for potential DIC. Decreased fibrinogen is the best test for DIC.
69
Therapy-related AML (t-AML)
is defined as AML arising secondary to DNA damage from a prior therapy. It is usually due to previous treatment with DNA alkylating agents or topoisomerase-II inhibitors. In addition, some persons who received ionizing radiation to large fields of active marrow may develop t- AML. t-AML accounts for 10% to 20% of cases of AML. t-AML secondary to alkylating agents or radiation: usually has a latency of 2-8 years form prior treatment, frequently progresses through an initial MDS stage before reaching outright AML (20% blasts), and frequently has a complex karyotype that includes whole or partial loss of chromosomes 5 and/or 7.
t-AML secondary to topoisomerase-II inhibitors: usually has a latency period of 1-2 years from prior treatment - frequently presents as de novo AML with no prior MDS phase, often has a rearrangement of the MLL gene (11q23). All types of t-AML have a very poor prognosis.
70
AML Not otherwise specified (NOS):
Around 50% of cases of AML have none of the recurrent cytogenetic findings of AML, and these often have a normal karyotype. In the absence of a history that would allow a diagnosis of t-AML, or a history of MDS, these cases are classified as AML, NOS.
71
Features evaluated in AML, NOS:
The line of differentiation of the leukemic cells can provide some prognostic info. Myeloid - leukemic cells are myeloblasts.
Myelomonocytic - leukemic cells are mixture of myeloblasts and monoblasts/monocytes.
Monoblastic/monocytic - leukemic cells are monoblasts and/or monocytes. (Monocytic differentiation is important to note as leukemic monocytes often infiltrate the skin and gums, resulting in many small lesions). Erythroid - leukemic cells are myeloblasts, but background erythroid precursors are markedly increased. Megakaryoblastic - leukemic cells resemble megakaryoblasts and/or megakaryocytes, often present with significant marrow fibrosis. The presence of certain molecular findings are currently the most important prognostic finding for AML, NOS
72
FLT3 ITD
Positivity for internal tandem duplications (ITDs) in the FLT3 gene are a negative prognostic factor for AML, NOS
73
NPM1
Positivity for a mutation of the nucleophosmin-1 gene is a positive prognostic factor in AML, NOS (but only if it is negative for the FLT3 ITD).
74
CEBPA
Positivity for a mutation of the CEBPA gene is a positive prognostic factor in AML, NOS (but only if it is negative for the FLT3 ITD).
75
AML prognosis
Mean survival times for AML patients range from less than 1 year for patients with adverse risk cytogenetics, to more than 10 years in patients with favorable risk cytogenetics. Approximately 60% of AML cases will reach complete remission after chemotherapy. Rate of relapse varies according to prognostic factors. For many patients with AML with poor prognostic factors, or for many patients with relapsed AML, autologous stem cell transplant (SCT) is the preferred treatment. Due to the high morbidity of the transplant process, consideration of SCT must take into account the patient's performance status (i.e. a measure of the patient's overall health/robustness).
76
Characterize the infections you would expect in a pure B cell deficiency and in a pure T cell deficiency.
T deficiencies are associated with severe infections with intracellular pathogens, including viruses, certain bacteria, and yeasts and fungi, especially Candida albicans and Pneumocystis jirovecii. B cell deficiency is characterized by infections with “high-grade” (extracellular, pyogenic = pus-producing) bacterial pathogens such as Staphylococcus aureus, Haemophilus influenzae and Streptococcus pneumoniae. Gut organisms may be abnormal in either type of disease, so diarrhea and malabsorption are frequent complaints, as is failure to grow normally.
77
Signs and symptoms of DiGeorge
may include birth defects such as congenital heart disease, defects in the palate, most commonly related to neuromuscular problems with closure (velopharyngeal insufficiency), learning disabilities, mild differences in facial features, and recurrent infections. Infections are common in children due to problems with the immune system's T-cell-mediated response that in some patients is due to an absent or hypoplastic thymus. 22q11.2 deletion syndrome may be first spotted when an affected newborn has heart defects or convulsions from hypocalcemia due to malfunctioning parathyroid glands and low levels of parathyroid hormone (parathormone). May also have any other kind of birth defect including kidney abnormalities and significant feeding difficulties as babies. Disorders such as hypothyroidism and hypoparathyroidism or thrombocytopenia, and psychiatric illnesses are common late-occurring features. Microdeletions in chromosomal region 22q11.2 are associated with a 20 to 30-fold increased risk of schizophrenia.
78
DiGeorge syndrome
Caused by a deletion on chromosome 22. The thymus is a two-component organ. The lymphoid part comes from precursors in the bone marrow; the stroma is derived in the embryo from the endoderm and ectoderm of the 3rd and 4th pharyngeal pouches. If these develop abnormally the stroma will not support thymic lymphoid development, and the patient will have absent T cells with normal B cells. The parathyroids also derive from the pharyngeal pouches, so this diagnosis is sometimes made in infancy when there are unexplained convulsions controllable by calcium. The great vessels of the heart develop abnormally, too. Cell-mediated immunity is depressed; viral and fungal infections are common. Incidence about 30/100000 births.
79
x-linked (burton) agammaglobulinemia
when there are normal T cells but low to absent B cells caused by a block between pre-B and B cells causing most patients to have deficient B cells and antibody (IgA and IgM are undetectable). This is caused by a defect in protein tyrosine kinase (btk), normally expressed in pre-B cells and B cells. Boys have bacterial infections causing pneumonia and chronic diarrhea. Enteroviruses gain entry through the mucous membranes unprotected by IgA (oral live polio virus vaccine). Incidence about 0.4/100,000 births.
80
x-linked hyperIgM syndrome
Along with high IgM, patients also have low IgG and IgA because of a defect in IgM to IgG switching. The Tfh cell has an accessory molecule (CD40- ligand) that interacts with CD40 on B cells, signaling them to switch classes. If either molecule is defective, the B cell is driven hard but can’t be instructed to switch past making IgM.
81
Common variable immunodeficiency (CVID):
there are normal levels of pre-b and b cells but the b cells have trouble being triggered to make specific antibody. IgG is low, 0.5g/dL or less. This is a group of probably about 20 conditions and can be diagnosed in older ppl. The main phenotype is recurrent bacterial infection. Treated with IVIG or SCIG. There is increased risk for lymphoma, enteropathy, or autoimmunity. The causes are unknown, but innate immunity as well as B and T cell defects have been described.
82
Transient hypogammaglobulinemia of infancy
Noticed around 6 months and lasting up to 18 months. These kids are slow to get their production of IgG going and mostly present with recurrent and persistent gram-positive bacterial infections, but can contract much more. Perhaps 15% of all chronic diarrhea in infants is due to this condition.
83
Selective IgA deficiency
the most common immunodeficiency disease with an incidence of 1 out 500. Although it is usually asymptomatic, the patient may have diarrhea and sinopulmonary infections, or an increased frequency and severity of allergies. There is a familial tendency, and mechanism are not clear. It is 10-15 times more frequent in people with celiac disease. Some seem to be able to secrete IgM into their mucosal.
84
Nude mice
have quite a different mutation, but also fail to make a thymic stroma (and hair) and so they have no T cells, and are immunologically similar to DiGeorge kids.
85
Severe combined immunodeficiency disease
If there are low numbers of T and B cells, then there is a block in the development of the lymphoid stem cell or its further maturation. Signs and Symptoms include lymphopenia of both B and T cells, absent thymic shadow on X-ray and small tonsils; serum immunoglobulins are low. Majority of these cases are X-linked; the most common being SCID-X1, which causes a defect in the gene for the gamma chain that forms part of the receptor for IL-2 and other growth factors needed for lymphoid development or their signaling pathway. Not having IL-7 can also cause arrest in development of T and C cells. The rest of the cases are autosomal recessive and most of these patients lack adenosine deminase (ADA), which causes an accumulation of adenosine in all cells but impairs lymphocyte (express more ADA than any other cell) development the most. There are also also rarely defects in V(D)J recombination; recombination machinery for b and t cells is basically the same (SCID A default in artemis; RAG recombinase).
86
Treament of ADA asscociated immunodeficiency disease
Purified ADA, stabilized with polyethylene glycol (“PEGylated”), is also available for use as a drug. The first-ever successfully gene replacement therapy in humans has been done in ADA- deficient and SCID-X1 children. But problems have arisen: The vector bearing the normal gene preferentially inserted itself near oncogenes, activating their expression and causing leukemia. Better lentiviral vectors have, it seems, obviated that problem, and kids are once again being given replacement gene therapy.
87
Transplantation in DiGeorge
fetal thymus or cultured thymic stromal cells have been used to try to minimize the risk of graft-versus-host disease. Some success is claimed; better diagnosis would aid in the selection of appropriate cases. The thymic stroma is a donor but the T cells are the patients.
88
Transplantation for SCID
bone marrow transplantation has about a 50% success rate, but graft-versus-host disease is always a problem. It is better to transplant purified stem cells than whole bone marrow. Sibling donors are the best, and a good Class II MHC match is imperative. For ADA- deficient patients, transfusions of irradiated red cells can be helpful, to kill T cells preventing graph vs. host reactions, without harming the RBC.
89
Test for B cell deficiency
serum protein electrophoresis, quantitative IgG, IgA, IgM levels, specific antibodies to prior immunization, ABO isohemagglutinins, antibody response to novel antigens, and sequencing suspect gene.
90
Test for T cell deficiency
Skin test with recall antigen panel, total lymphocyte, CD3 CD4 CD8 counts, and mitogen responses, MLR, cytokine measurements.
91
Tests for phagocyte deficiency:
WBC count, differential, morphology, NBT test, oxidative burst, assays for phagocytosis chemotaxis, and genetics
92
Tests for complement deficiency
CH50, assay for C1 inhibitor, and individual complement component levels.
93
IVIG
human immunoglobulin, given monthly when B cell function is deficient. It is pooled from many donors, and is usually about 99% IgG, with a half-life of 3 weeks.
94
Name two viruses, which are immunosuppressive in humans. Discuss a possible mechanism for the immunosuppression caused by one of these viruses.
Measles, EBV- gets into B cells and makes B cells divide (infectious mono).
95
Myelodysplastic syndrome (MDS)
refers to a group of clonal hematopoietic stem cell disorders characterized by: ineffective hematopoiesis (clone is not able to make normal functioning blood cells and are dysplastic) and increased risk of transformation to acute myeloid leukemia (MDS is considered a precursor to acute myeloid leukemia). These clones replace the marrow to a varying extent, and result in ineffective production of blood cells in one or more of the myeloid lineages (granulocytic, erythroid, and/or platelet)
96
MDS therapy
Younger patients, or older patients with good performance status and a type of MDS likely to progress, may be treated with allogeneic stem cell transplant.
Most MDS patients are treated with supportive care, including transfusions for their cytopenias when necessary.
97
Primary / Idiopathic MDS
Usually in persons over 50 years old, insidious onset. Median age of diagnosis is 70. Incidence estimated at 3-5 cases per 100,000 persons per year.
98
Secondary / Therapy-Related (t-MDS)
Occurs as part of the spectrum of t-AML. Usually occurs 2-8 years after use of alkylating agents or exposure of fields of active marrow to ionizing radiation. Usually contains whole or partial deletions of chromosomes 5 and/or 7.
99
MDS diagnosis
is considered when there has been at least one persistent cytopenia. If these is only one cytopenia it is usually anemia, but rarely persistent isolated neutropenia or persistent isolated thrombocytopenia can be due to MDS. Persistent cytopenias of two or more lineages is in an elderly person is suspicious for MDS. Bone marrow should show morphologic evidence of dysplastic changes in at least 10% of the cells in one or more lineages (dyshematopoiesis), such findings could include dyserythropoiesis, dysgranulopoiesis, and dysmegakaryopoiesis. Clonal cytogenetic findings can also diagnose MDS. In the absence of clonal cytogenetic evidence of MDS (or of increased myeloblasts, see below), care should be taken in establishing a diagnosis of MDS. Potential non-neoplastic causes of secondary myelodysplasia should first be excluded.
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Clonal cytogenetic findings typical of MDS
Complex karyotypes including monosomy 7, deletion 7q, monosomy 5, or deletion 5q; often seen in t-MDS, but also seen in de novo MDS. Deletion 5q as an isolated cytogenetic abnormality; seen with a specific type of MDS. Trisomy 8; and many others.
101
Dyserythropoiesis
RBC precursors with nuclear budding, irregularly-shaped nuclei, lack of coordination between nuclear and cytoplasmic maturation, increased ring sideroblasts (increased iron storage)
102
Dysgranulopoiesis
Nuclear hypolobation of mature neutrophils, including neutrophils with bilobed nuclei called pseudo-Pelger-Huet cells (because they resemble the bilobed nuclei seen in the neutrophils of patients with Pelger-Huet anomaly, a benign congenital condition), also cytoplasmic hypogranularity of neutrophils
103
Dysmegakaryopoiesis
Megakaryocytes with hypolobated or non-lobated nuclei, often hyperchromatic nuclei, megakaryocytes often of small size
104
List 4 possible causes of secondary myelodysplasia that might mimic MDS.
Certain drugs, including many chemotherapeutic drugs; Deficiencies of vitamin B12, folic acid, or certain essential elements; Viral infection; Toxin exposure, especially heavy metals such as arsenic
105
Low grade MDS
Myeloblasts account for less than 5% of marrow cells, and less than 2% of peripheral blood cells.
Types include RC-UD, RC-MD. And isolate deletion of 5q.
106
Refractory Cytopenia with Unilineage Dysplasia (RC-UD):
Low grade MDS. May be further clarified based on what lineage is dysplastic, i.e. Refractory Anemia or Refractory Neutropenia
RC-UD has relatively good prognosis, regardless of which lineage is affected. For example, Refractory Anemia has a median survival from diagnosis of over 5 years, with a rate of transformation to AML of only 2% at 5 years.
107
Refractory Cytopenia with Multilineage Dysplasia (RC-MD
Low grade MDS (i.e. myeloblasts not increased) with evidence of dysplasia in 2 or more lineages. Worse prognosis than RC-UD, with median survival of 2.5 years, and rate of transformation to AML of 10% at 2 years
108
MDS with isolated deletion 5q
Unique type of low grade MDS, associated with anemia, often with increased platelets, and marrow showing distinctive megakaryocytes with small, round, non-lobated nuclei.
109
High grade MDS
Myeloblasts account for 5% or more of marrow cells, and/or 2% or more of peripheral blood cells. Regardless of which lineages are affected by dysplasia, cases of MDS with increased myeloblasts (high grade MDS) are classified as either RAEB-1 or RAEB-2. Prognosis for high grade MDS is dismal; even if patients don't progress to AML they frequently die secondary to their bone marrow failure.
110
Refractory Anemia with Excess Blasts-1 (RAEB-1):
high grade MDS. 5-9% blasts in marrow or 2-4% blasts in the peripheral blood. RAEB-1 has median survival of 16 months, and 25% of patients transform to AML.
111
Refractory Anemia with Excess Blasts-2 (RAEB-2):
high grade MDS. 10-19% blasts in marrow or 5-19% blasts in the peripheral blood. RAEB-2 has median survival of 9 months, and 33% of patients transform to AML
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Myeloproliferative neoplasms (MPNs):
MPNs are clonal hematopoietic stem cell disorders characterized by proliferation of one or more myeloid lineages (specifically granulocytic, erythroid, megakaryocytic, and/or mast cell) but still make normal blood cells in one or more lineages.
Typically, MPNs are a disease of adults in their 50s-70s, but they may occasionally occur in children and young adults. Incidence of all MPNs is around 6-10 per 100,000 persons per year. Early in the disease course the MPNs are characterized by quantitative increase in one or more blood cell types (neutrophils, platelets, and/or RBCs), usually with a correspondingly hypercellular marrow MPNs often present with splenomegaly and/or hepatomegaly. MPNs usually have an insidious onset, and are often incidentally noticed on CBC results. MPNs are usually associated with abnormalities of genes (translocations, point mutations) that encode cytoplasmic or receptor protein tyrosine kinases (PTKs). The main types of MPNs identified by the WHO are: 1) Chronic myelogenous leukemia (CML)
2) Polycythemia vera (PV)
3) Primary myelofibrosis (PMF) 4) Essential thrombocythemia (ET).
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List 2 reasons for the frequent occurrence of splenomegaly and hepatomegaly in patients with MPNs.
sequestration of excess blood cells and extramedullary hematopoiesis
114
List 3 possible negative end points for MPNs
1. transformation to acute leukemia (usually AML, but sometimes ALL, much less than for MDS) (in the setting of a prior MPN, transformation to acute leukemia is often referred to as blast phase). 2. development of myelodysplasia with ineffective hematopoiesis (transform to MDS). 3. excessive marrow fibrosis with resultant bone marrow failure
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CML
is a clonal hematopoietic stem cell disorder, associated with the presence of the BCR-ABL1 gene fusion, and most prominently manifesting as a prominent neutrophilic leukocytosis.
116
CML CLINICAL FINDINGS / EPIDEMIOLOGY
Initial signs/symptoms may include fatigue, weight loss, night sweats, splenomegaly, and anemia, but a significant minority of patients will be asymptomatic and diagnosed due to a CBC revealing a markedly increased neutrophil count.
Incidence is 1-2 cases per 100,000 persons per year
Typical age at diagnosis is 40s and 50s
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CML chronic phase
In this phase, blasts are not significantly increased in the marrow or blood. There is usually a prominent leukocytosis due to a neutrophilia. The WBC count may range anywhere from 12,000 to 1,000,000 , and averages around 100,000 (average upper limit of normal for WBC count at UCH is 11,000). In addition to the neutrophilia, basophils are also almost always increased, and platelets are often increased but may be normal. Bone marrow biopsy during chronic phase would show a markedly hypercellular marrow due to a granulocytic hyperplasia. Also, many small megakaryocytes with round, non-lobated nuclei. There would be no dysplasia seen in the marrow or blood. Blasts are not increased
118
CML blast phase
If left untreated, CML could progress rapidly to blast phase, which is essentially transformation to acute leukemia, with 20% or more blasts in the marrow or blood.
In CML blast phase, the blasts are myeloblasts in about 70% of cases (AML), and lymphoblasts in about 30% of cases (ALL).
119
CML accelerated phase
may progress through an intermediate phase before reaching blast phase.
120
GENETICS
CML
is partially defined by presence of the BCR-ABL1 gene fusion. In the majority of cases, this fusion results from a translocation (9;22)(q34;q11.2), with the resultant BCR-ABL1 fusion gene being located on the derivative chromosome 22, which is referred to as the Philadelphia chromosome.
The fusion usually involves the major breakpoint cluster region in the BCR gene (M-BCR), resulting in a 210 kilodalton fusion protein (called p210). Less typical are cases with breakpoints in the minor breakpoint cluster region of BCR (m-BCR), resulting in a 190kd fusion protein (called p190), identical to the fusion protein often seen in Philadelphia chromosome-positive adult B-ALL.
In either case, the BCR-ABL fusion protein results in consitutive activation of several growth pathways.
121
CML diagnosis
requires documentation of presence of the BCR-ABL fusion.
This can be done using either peripheral blood or marrow samples, via: Conventional cytogenetics (karyotyping), FISH (BCR-ABL fusion probes), RT-PCR of BCR-ABL mRNA transcriptis (has benefit of detecting rare cases having variant translocations)
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CML treatment and prognosis
Untreated, CML had a median survival of 2-3 years.
BCR-ABL fusion protein allowed the development of small molecular inhibitors of this protein (the first of a family of agents called PTKIs, for protein tyrosin kinase inhibitors). The first PTKI for CML, imatinib (Gleevec). With imatinib, complete cytogenetic response rates (i.e. BCR-ABL not detectable by karyotyping or FISH) rose to 70-90%, with 5-year progression free survivals and overall survivals ranging from 80-85%.
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Polycythemia vera (PV):
PV is an MPN characterized primarily by an increase in RBC mass (erythrocytosis), usually accompanied by increased neutrophils and platelets, and with the bone marrow showing trilineage hyperplasia. Bone marrow biopsy also typically shows clusters of large, bizarre megakaryocytes.
Nearly all cases of PV contain a mutation of the JAK2 gene encoding the JAK2 cell signaling protein. Most contain the V617F point mutation.
If presence of a JAK2 mutation cannot be documented in a patient with persistent erythrocytosis, consider the possibility of a secondary erythrocytosis, which is seen most commonly in smokers (due to carboxyhemoglobin formation), but is also seen in other conditions such as chronic hypoxia, certain hemoglobin disorders, and others. PV usually presents in a polycythemic stage, with increased peripheral blood cell counts. Over time, PV can progress to a spent phase (aka post-PV myelofibrosis), where the marrow shows prominent fibrosis (myelofibrosis), and peripheral blood cell counts fall, with findings similar to primary myelofibrosis. The possibility of PV should always be considered in a patient with thrombosis of the mesenteric vein, portal vein, or splenic vein.
Other signs/symptoms of PV include headaches, dizziness, visual problems, paresthesias ("pins-and- needles"), plethora (dusky, reddish skin), and itching. 70% of PV patients have splenomegaly and 40% have hepatomegaly at diagnosis.
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PV prognosis
is very good relative to other MPNs, with current median survival times of 10-20 years. Mainstays of therapy are serial phlebotomy (bloodletting) and aspiring therapy, to decrease the risk of clots. Occasional, mild chemotherapy drugs may be used if the patient has problems despite phlebotomy, but these are believed to possibly increase the risk of transformation to MDS or AML, which is normally very low at around 2% of cases of PV. Most patients who die due to their PV die of thrombotic events.
125
PTKIs
The PTKIs (imatinib/ gleevec) effectively select from new subclones against which the PTKI is not effective, for reasons such as mutation of the PTKI binding site. Thus, a second generation PTKI for CML, dasatinib, was developed and released, and now subsequent generations are also available.
126
Primary Myelofibrosis (PMF):
PMF is an MPN characterized by proliferation of the granulocytic and megakaryocytic lineages, with eventual progression to myelofibrosis (thus, it's very similar to PV, but lacks the erythrocytosis). Mutations of JAK2 can be found in around 50% of cases of PMF. Cases lacking JAK2 mutations often have mutations of MPL or CALR
127
PMF prefibrotic stage
the marrow is hypercellular, showing a granulocytic and megakaryocytic proliferation. Like PV the megakaryocytes are frequently large and bizarre, and present in clusters. In the blood, there is usually a marked thrombocytosis, and there may or may not be a prominent neutrophilia as well.
PMF eventually progresses to the fibrotic stage.
128
PMF fibrotic stage
Features of the fibrotic stage include: Bone marrow with significant reticulin fibrosis (reticulin is type 4 collagen), with loss of much of the marrow space. This may result in hematopoiesis being present within the marrow sinusoids, so-called intramedullary extramedullary hematopoiesis. The peripheral blood shows a picture known as leukoerythroblastosis. Other organs may become enlarged due to increased extramedullary hematopoiesis
as the marrow space is replaced by fibrosis. This is most prominent in the spleen, but can also involve the liver, lymph nodes, and many other organs. Dacrocytes (tear drop- shaped RBC) are seen.
129
PMF PROGNOSIS / THERAPY
Most PMF patients are not diagnosed until they have reached the fibrotic stage, at which time they have median survivals of around 5 years. Survival times are much longer if diagnosed in the prefibrotic stage. Most deaths due to PMF result from bone marrow failure secondary to fibrosis. Transformation to AML occurs in a minority of cases.
130
Essential Thrombocythemia (ET):
ET is an MPN characterized by a sustained marked thrombocytosis. It differs from PMF in that there is no granulocytic hyperplasia in the marrow (the marrow is usually normocellular in ET), and the clustered atypical megakaryocytes in the marrow are even larger and more bizarre than in PMF.
Like PMF, mutations of JAK2 can be found in around 50% of cases of ET.
Cases lacking JAK2 mutations often have mutations of MPL or CALR. Around half of ET patients have no symptoms, and are diagnosed incidentally due to markedly increased platelet counts.
131
Signs/symptoms of ET
are usually due to occlusion of small blood vessels, and include: transient ischemic attacks (TIAs) (these are essentially small strokes causing no permanent damage); digital ischemia with paresthesias; thrombosis of major arteries or veins (less common than in PV); splenomegaly is not common in PV, and is more suggestive of another MPN
132
ET PROGNOSIS
ET is an indolent disease, with median survivals of 10-15 years or more. The natural course of ET is to be symptom free for long periods, with occasional severe thrombotic or hemorrhagic events.
Only rare cases of ET transform to AML or develop myelofibrosis.
133
Recall the most common method of death attributable to disease in polycythemia vera (PV) patients, and list 3 sites where thrombosis should always make one consider the possibility of PV.
The most serious complications of PV are the predilection for venous or arterial thrombosis, which occurs in around 20% of patients, and can present as DVT, myocardial ischemia, stroke, or other thrombotic event.
134
Recall the (somewhat archaic) most common treatment for PV.
Blood letting
135
Describe findings that might be seen in a peripheral blood smear of a patient with leukoerythroblastosis and how these findings relate to patients with marrow fibrosis.
There are increased immature granulocytes (myelocytes, metamyelocytes) and increased immature nucleated red blood cells present. In addition, there are many tear drop- shaped red blood cells (dacrocytes).
136
antibody-dependent cell-mediated cytotoxicity (ADCC)
is a mechanism of cell-mediated immune defense whereby an effector cell of the immune system actively lyses a target cell, whose membrane-surface antigens have been bound by specific antibodies. It is one of the mechanisms through which antibodies, as part of the humoral immune response, can act to limit and contain infection. Classical ADCC is mediated by natural killer (NK) cells; macrophages, neutrophils and eosinophils can also mediate ADCC. For example, eosinophils can kill certain parasitic worms known as helminths through ADCC. ADCC is part of the adaptive immune response due to its dependence on a prior antibody response.
137
Type II mechanism in heart
Some people have ‘inappropriate’ tachycardia, a fast heart rate without cardiac abnormalities. About half have been shown to have autoantibodies to the β-adrenergic receptor, which are stimulatory, like epinephrine; the effect can be reversed by the beta blocker propranolol. Most of the autoantibody-positive patients are women, as is often the case in autoimmunity.
138
Rheumatic Heart Disease
heart disease occurring shortly after a streptococcal infection, for example a ‘strep throat.’ There is very good evidence that it is due to cross-reaction between a Group A Streptococcus M-protein antigen and a structure on the heart’s endothelial lining, probably laminin on heart valves, followed by neutrophil-mediated tissue destruction. Rheumatic fever is the same disease with more widespread manifestations, including in the skin and CNS.
139
Dressler syndrome
Most people who have a heart attack will make some autoantibody which reacts with heart. This seems to do them no harm. Dressler syndrome manifests as persistent cardiac pain, fever, malaise, and pericardial effusion seen after heart attack (and more commonly after heart surgery) which is directly related to an immune response to pericardial or myocardial antigens. A better name might be post-cardiac injury syndrome. Treated with anti- inflammatory agents, it usually gets better as the heart heals.
140
Autoimmune thrombocytopenic purpura (ATP):
also called idiopathic thrombocytopenic purpura. These patients have bleeding abnormalities due to destruction of platelets (thrombocytes) by autoantibody; the platelets are opsonized and their destruction, mainly in the spleen, is rapid. Platelets are needed, of course, for blood clotting. (Treatment: suppress the immune system and/or remove the spleen.) ATP is often seen in young healthy people some weeks after a viral infection; in older people, in association with many other autoantibodies; and in people treated with certain drugs.
141
Autoimmune hemolytic anemia (AIHA):
Like ATP, this may follow a viral infection, or be associated with another autoimmune syndrome, or cancer. Many drugs, such as penicillin, methyldopa, chlorpromazine and quinidine, can induce AIHA, usually temporarily. In the rare condition paroxysmal cold hemoglobinuria (PCH), the patient experiences hemolysis after exposure to cold. It is due to an autoantibody, which only binds to red cells at about 15° C.
142
Systemic Lupus Erythematosus
multifactorial autoimmune disease, with both genetic and environmental causes and triggers. Many think it could be a disorder of the management of apoptotic cells, which are normally recognized and taken up for reprocessing via receptors that do not activate phagocytes to become antigen-presenting. If by some accident uptake was mediated by FcγR, they say, the activated phagocytes might then be able to break normal self-tolerance. There are a number of different mouse models in which most or all animals get lupus-like symptoms of immune-complex glomerulonephritis (Type III) and a variety of autoantibodies (Type II); the best known of these are the NZB x NZW F1 hybrid mice. Even in this simple model, many genes are implicated. The incidence in mice and people is considerably greater in females, partially an estrogen effect. People with lupus may make antibody to: nuclear and nucleolar proteins; DNA; RNA; erythrocytes; clotting factors; platelets; skin; and T cells. Antibody to double-stranded DNA is pathogenic, and may explain not just the kidney disease but also the characteristic facial butterfly rash, with local immune complex formation near sun-damaged, DNA-releasing skin cells. In the US the incidence of SLE is 1/3500; it is higher in Black, Hispanic, and Asian populations.
143
Hashimoto thyroiditis
An inflammatory disease of the thyroid in which there is very good evidence for both T and B cell immunity to various thyroid antigens, including thyroglobulin. The antibodies to thyroid antigens are destructive, not stimulatory. Histologically the thyroid is infiltrated by T cells. It may be that T cell damage allows antibodies access to normally sequestered antigens, which worsens the condition. The result is hypothyroidism.
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OTHER DISEASES
There are often autoantibodies found in conditions that are known to be T cell-mediated; this indicated that immunity may be generally dysregulated. In celiac disease, there is an antibody to tissue transglutaminase that is very useful for diagnosis, and in Type 1 (childhood) diabetes several antibodies to islet-associated antigens are seen which provide prognostic information; but in neither of these conditions are they thought to be pathogenic, so diabetes is considered under Type IV immunopathology, and celiac under Chronic Frustrated Immune Responses.
145
Goodpsture’s syndrome
This uncommon
condition involves formation of autoantibodies to
lung and kidney basement membranes (BM) (which
are the collagenous non-living connective tissue
framework upon which the endothelial cells of
capillaries sit). There is an antigen (Type IV
collagen) shared between the BM’s of these two
organs, because other organs are not involved. The
patients have persistent glomerulonephritis, and
pneumonitis with pulmonary hemorrhages. This was
the first human autoimmune disease in which the
antibody was proved to cause the condition: kidneys
were removed from a patient who had died of Goodpasture, the antibody eluted from them (low pH breaks antigen-antibody bonds), purified, and injected into a chimpanzee, who came down rapidly with typical Goodpasture syndrome. In Goodpasture the antibody is directed against the basement membrane, not trapped as clumps, so the staining by immunofluorescence is sharp and ‘linear,’ not ‘lumpy-bumpy’ as it is in Type III, immune complex conditions.
146
Distinguish between the "lumpy-bumpy" and "linear" immunofluorescent patterns in terms of the most probable immunopathologies they represent.
Lumpy bumpy probably means Type II because it represents components trapped in clumps. The linear is type II because it is an autoimmune antibody reacting with the basement membrane.
147
Direct test
looking for antibody in the patient’s tissues, if you happen to have a sample of the patient’s tissues.
148
Indirect test
Or, if you only have the patient’s serum, you can look for antibody in it by an indirect immunofluorescence test, using normal human tissue (autoantibodies are almost always tissue specific but not individual-specific)
149
Foreign plus self hybrid antigen mechanism:
```
Suppose you had
anti-self B cells that hadn’t
been deleted. They would not
get you into trouble if the self
antigens were T-dependent,
and you did not have antiself
follicular T helper cells. This
actually seems to be the case
for many, maybe most self
antigens. But: suppose that a
foreign protein were to
couple to the self antigen.
The anti-self B cell could
bind and ingest self, and
carry the foreign antigen
along with it. Then foreign
epitopes might be presented
to a Tfh on the B cell’s Class
II MHC. The B cell would then receive both necessary signals (from its receptor and from the Tfh cell) and become activated. Then it would make its antibody, against self. It would also be instructed by the Tfh to class-switch.
```
150
Emergence of a forbidden clone mechanism
A clone might somehow escape the normal clonal deletion mechanisms, and mature so that encounters with antigen immunize it. This has been described in some cases of myasthenia gravis, and other syndromes.
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Cross reaction mechanism
the theoretical possibility that sequence similarities between foreign and self-peptides are sufficient to result in the cross-activation of autoreactive T or B cells by pathogen-derived peptides. Despite the promiscuity of several peptide sequences which can be both foreign and self in nature, a single antibody or TCR (T cell receptor) can be activated by even a few crucial residues which stresses the importance of structural homology in the theory of molecular mimicry. Upon the activation of B or T cells, it is believed that these "peptide mimic" specific T or B cells can cross-react with self-epitopes, thus leading to tissue pathology (autoimmunity). By the time the patient develops clinical symptoms, the triggering antigen may be long gone, with the process being maintained by autoimmune responses to normally-sequestered antigens released from damaged cells.
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Passive antibody mechanism
the transfer of active humoral immunity in the form of ready-made antibodies, from one individual to another. Passive immunity can occur naturally, when maternal antibodies are transferred to the fetus through the placenta, and can also be induced artificially, when high levels of human (or horse) antibodies specific for a pathogen or toxin are transferred to non-immune individuals. In a child with hemolytic disease of the newborn; in a patient getting a mismatched transfusion; in a child of a mother with myasthenia gravis or SLE.
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Innocent bystander mechanism
A common mechanism, in which there is damage to normal tissue which happens to be associated with or infected by the antigen, which is truly foreign. Imagine a drug adhered to your red cells, and you made antibody against the drug. What would get lysed by complement—the drug? No, the red cell.
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Release of a sequestered antigen mechanism
Note that in the special case of sequestered antigens, the antigen cannot get out into the general system, and therefore is not normally immunogenic, but if an immune response does get initiated, then the response can usually get into the place where the antigen was sequestered. Example: some men who get mumps end up sterile. It is thought that the mumps breaks down the blood/testis barrier, allowing immunization to normally-sequestered sperm antigens.
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epitope spreading
Early in the disease antibodies are made to just one or two epitopes of some “self” protein. With time, more epitopes, and more proteins are involved. Does tissue damage gradually reveal more sequestered antigens?
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Failure of regulatory mechanisms
A proper balance between Th1, Th17, Tfh, Th2, and Treg activity assures that immune responses are appropriate. Does this balance get perturbed in some way, so that some responses are exaggerated, and eventually self/non-self discrimination breaks down? This is an area of intense speculation lately. Some recent experiments that cause major shifts in T cell balance look very promising as therapy, if they can make the translational jump from the lab or the Phase I trial into safe general use.
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Rheumatoid Arthritis
This is probably the most common autoimmune disease, affecting more than 1 in 100 Americans. It is the ‘inflammatory arthritis.’ (Osteoarthritis, the ‘degenerative arthritis,’ where the joints wear out, is even more common.) RA affects women more than men, and usually attacks the smaller joints, especially those of the fingers, first. The initial evidence that it was autoimmune came with the discovery of rheumatoid factor (RF). RA is linked to the gene PADI4 (a deiminase that converts arginine in proteins to citrulline.) This is intriguing, since antibodies to citrullinated peptides seem to be absolutely specific to RA, though their role in pathogenesis is not known. Although at its earliest stages RA seems to be antibody- mediated, eventually most of the pathogenesis is due to T cells.
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Rheumatoid factor
can be detected by adding the patient’s serum to microscopic beads that are coated with normal human IgG. RF makes the beads agglutinate; It is IgM anti-IgG It is a useful biomarker, but may not actually cause much joint damage. There are other antibodies involved, as well as T cells, so the pathogenesis is complex (and the etiology is unknown). Although it’s been difficult to identify a pathogenic antibody (unlike the case in lupus), nevertheless RA can respond extremely well to rituximab, a monoclonal antibody against the CD20 on the surface of B cells, which effectively depletes them from the body. Air pollution, and especially smoking, is an important RA risk factor; and it increases citrullinated proteins in the lung.
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Graves Disease
may consist of hyperthyroidism, goiter, eye disease (orbitopathy), and occasionally a dermopathy referred to as pretibial or localized myxedema. the main autoantigen is the thyroid stimulating hormone receptor (TSHR) which is expressed primarily in the thyroid but also in adipocytes, fibroblasts, bone cells, and a variety of additional sites
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Myasthenia gravis
A disease of progressive muscle weakness, because patients are making antibody to the acetylcholine receptor (AChR). The antibody to the alpha subunit of the AChR does the real damage, which is complement- and neutrophil-mediated. The thymic transcription factor Aire drives the thymic expression of CHRNA1, the gene for the AChR alpha subunit. Two kindreds were found to have an allele of the CHRNA1 promoter that does not interact with Aire, so the protein is not expressed in patients’ thymuses, and Th clones reactive with the AChR are not deleted by negative selection. Tfh are therefore available to help B cells make antibody to the receptor. In the majority of patients the thymus becomes abnormal, with hyperplasia and even, sometimes, the appearance of germinal centers. Perhaps Th against the AChR attack that antigen on the surface of intrathymic muscle cells, leading to chronic inflammation. In such patients, thymectomy often yields dramatic improvement. Treatment may include immunosuppression, neostigmine-related drugs to increase the effectiveness of residual Ach, and IVIG.
