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Immunodeficiencies Flashcards

(60 cards)

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1
Q

Signs suspecting immunodeficiency

A 
All occur in 1 year
8 or more ear infections
2 or more sinus infections
2 or more bouts of pneumonia
2 or more deep-seated infections
Family history of primary Immunodeficiencies
IV necessary to rid of infection
Recurrent abscesses
Unusual infections
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2
Q

Primary Immunodeficiencies

A

Occur in first year of life (5-6 months)
Not noticed as newborns because of mother’s IgG
Cause recurrent, protracted infection
Can be innate or adaptive immune problems

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3
Q

Innate immunodeficiencies

A

Phagocytic deficiencies

Complement deficiencies

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4
Q

Adaptive immunodeficiencies

A

T cell and B cell
T cell only
Antibody only (B cell)

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5
Q

Test for T-cell, T/B cell defects

A

Differential blood cell count

Look for decreased numbers of T cells, B cells, or platelets

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6
Q

Testing for T cell defects

A

DTH skin test

Negative-possible impaired T cell response

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7
Q

Testing for humoral immunodeficiency

A

Serum IgG, IgM, and IgA—> decrease in any or all

Ab testing to specific Ag after immunization —>decreased or absent Ab response to vaccine

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8
Q

Test for complement deficiency

A

Total hemolytic complement assay (CH50 classical, AH50 alternative)
Absence of hemolysis on CH50 testing
SLE shows decreased but not absent results
Decreased AH50 suggests a deficiency in Factor B, Factor D, or properdin
Decrease in both CH50 and AH50 deficiency in a shared complement component (C3 to C9)

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9
Q

Phagocytic disorder

A

Nitroblue tetrazolium test

Abnormal test result

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10
Q

Phagocytic cell defects

A

Primary phagocytic defects—> recurrent infection and fever
Susceptible to normally non pathogenic bacteria and fungi
Result from a mutation that affects the innate immune system

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11
Q

Phagocytic immune deficiencies

A 
Severe chronic neutropenia
Chronic granulomatous disease
Chediak-Higashi syndrome
Glucose-6-phosphate dehydrogenase (G6PD) deficiency
Myeloperoxidase deficiency
Leukocyte adhesion deficiency (LAD)
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12
Q

What do atypical mycobacteria suggest a defect in?

A

IFN-gamma and IL-12 axis

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13
Q

Severe Chronic Neutropenia

A

Defects in the life cycle and anatomy of neutrophils
Absolute neutrophil count is less than 500 cells per mm cubed
Suppressed inflammation and increased susceptibility to bacteria and fungi
Caused by mutation in GLI-1 gene
Cyclic neutropenia-mutation in elastase gene

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14
Q

Chronic granulomatous disease

A

Phagocytic disorder characterized by a tendency to form granulomas
Most frequent phagocytic PID
Enzymatic deficiency of NADPH oxidase in phagocytes
Cannot generate superoxide anion
Defective elimination of extracellular pathogens
Susceptible to recurrent infection with catalase-positive organisms

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15
Q

Myeloperoxidase deficiency

A

MPO catalyze the conversion of hydrogen peroxide to bleach; gives pus its green color
Autosomal recessive
Most common primary phagocyte disorder
Stain neutrophils for MPO activity
Diabetes mellitus show infections due to MPO deficiency

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16
Q

G6PD deficiency

A

X-linked recessive
Associated with anemia because G6P is important in RBC metabolism
Lack of substrate for NADPH
Asymptomatic
Manifestation is the same as CGD and characterized by the tendency to form granulomas

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17
Q

Chediak-Higashi syndrome

A

AR disorder
Become wheelchair-bound and usually die of infection in their early 30’s
Abnormal giant granules in neutrophils
Granules contain no Cathepsin G and Elastase
Defects in chemotaxis and degranulation
Prone to recurrent pyogenic granulomatous cause by staphylococci and streptococci
Response is a blunted neutrophilic due to delayed diapedesis
Biphasic immunodeficiency
First phase: susceptibility to infections
Second phase: accelerated lymphoproliferative syndrome with hepatosplenomegaly and lymphadenopathy
Diagnosis:
Azurophilic giant cytoplasmic inclusions in blood cells, partial albinism, no NK activity

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18
Q

Normal IFN-gamma-IL-12 axis

A

Positive regulatory loop
IL-12 produced by Mo and DC’s binds to IL-2R and stimulates IFN-gamma to be released by T cells and NK cells
Binding of IFN-gamma by Mo cross-link the IFNgammaR and activate the production of hydrogen peroxide and TNF-alpha and IL-12

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19
Q

Increased susceptibility to nontuberculous mycobacteria

A

Mutations in the genes encoding:
IFN-gamma receptor
IL-12 receptor
P40 subunit of IL-12

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20
Q

Leukocyte Adhesion Deficiency

A

Neutrophil count is 2x the normal level
History of recurrent infections of the oral and genital mucosa, skin, intestinal and respiratory tracts
Neutrophils unable to aggregate and do not bind to intracellular adhesion molecules on endothelial cells
Infected foci contain few neutrophils and heal slowly—>dysplastic scars
Mutation in LFA-1 family molecules (CD11 and CD18)
Early death

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21
Q

Clinical manifestations of LAD

A 
Late detachment of umbilical cord
Slow wound healing
Severe bacterial infections
Failure to form pus
Must do a flow cytometric assessment of neutrophil adhesion molecules CD11 and CD18
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22
Q

Systemic lupus erythematous

A

Abnormalities in C2, C1q, and C4
Polymorphism in FcgammaRII receptor
Estrogen altering B cell repertoire

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23
Q

When to expect complement disorders-classical pathway

A

Systemic lupus erythematous
Recurrent sinopulmonary infections, especially in C2 deficiencies
Defects in C3 look like humoral immunodeficiencies, but are less frequent
Defects in making the MAC show increased susceptibility to infections with Neisseria

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24
Q

When to expect complement disorders-alternative pathway

A

Deficiencies in properdin, factor B, and factor D present with severe Neisserial and other bacterial infections
Factor H deficiency—>hemolytic uremic syndrome or glomerulonephritis
C1 esterase inhibitor deficiency causes hereditary angiodema
Decay-accelerating factor (DAF) defects—>paroxysmal nocturnal hemoglobinuria

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25
Complement deficiencies
Not generally inherited The incidence is much higher in populations that have autoimmune diseases like SLE Result from the disruption of one of the proteins involved in activation pathways of complement Defects in the classical pathway are more common Pts with defects of the alternative pathway—>Neisseria infection
26
Deficiencies of the classical pathway
Normally responsible for clearance of Ig complexes, dying cells, and debris from damaged tissues Primary deficiency of C1 or C4—>SLE or rheumatoid arthritis (RA) C2 deficiency=most common, found in a slightly higher proportion of SLE pts and in children who have recurrent infections, primarily UR infections with Streptococcus
27
Hereditary angiodema (HAE)
Disease caused by deficiency in the C1 inhibitor Pts have recurrent swelling in the extremities, face, lips, larynx, or GI tract Swelling involves not complement enzymes, but the kinin-generating pathway—>Bradykinin Type I: C1-Inh decreased or not present Type II: C1-Inh is not working properly Type III: rare, unknown prevalence
28
What is the deficiency most likely in in alternative pathway deficiencies?
Properdin, then factors H,I, and then Factor D
29
Factor D deficiency
Very rare | Decreased AP function—>increases susceptibility to Neisseria bacteria
30
Factor B deficiency
Factor B-acute phase protein | Decreased AP function and increased susceptibility to Neisseria
31
Properdin deficiency
Only complement protein that is X-linked | Decreased AP function—>increased susceptibility to Neisseria
32
Factor H deficiency
Uncontrolled activation of the AP and depletion of C3 Associated with various forms of kidney disease Regulatory protein in complement
33
B cell deficiencies
``` X-linked agammaglobulinemia AR agammaglobulinemia IgA deficiency Common variable immunodeficiency X-linked hyper IgM Syndrome Hypoimmunoglobulinemia M (Wiskott-Aldrich syndrome; also partial T cell deficiency) Transient hypogammaglobulinemia of infancy Isolated IgG subclass deficiency ```
34
Adenosine Deaminase deficiency (ADA)
Combined immune deficiency affecting B cells, T cells, and NK cells
35
Agammaglobulinemias
Pre-B cell does not become an immature B cell | Fails to express antigen receptor—> cell death
36
X-linked agammaglobulinemia
X-linked; caused by mutations in BTK gene coding the Briton tyrosine kinase Low/absent IgG, IgA, and IgM Defect in rearrangement of the Ig heavy chain genes Early B cell development is arrested at the pre-B-cell stage—> circulating B cells are usually absent or present in very low numbers No mature B cells= no Ab producing plasma cells Lymphoid organs in which B cells proliferate are poorly developed or absent: Spleen, tonsils, adenoids, Peyer’s patches, peripheral lymph nodes
37
Autosomal recessive agamaaglobulinemia
AR; mutations in mu, Ig alpha, lambda5 genes, and BLNK BLNK: B cell linker or adaptor protein—>amplifies signal transduction Low/absent IgG, IgA, and IgM
38
Common variable immune deficiency
Heterogenous group of diseases associated with hypogammaglobulinemia-all isotopes or IgG only B cell maturation defects Both males and females are equally affected Mostly diagnosed older than 2 y.o.—>onset after 4-5 y.o. Low IgG, IgA, and IgM, but normal numbers of circulating B cells Abs against B cells (immune targeting, acquired) T-cell deficiencies also may occur All susceptible to recurrent bacterial infections
39
IgA deficiency
``` High incidence Asymptomatic Higher in male pts Pathogenic mechanism involves IgA secreting B cells—> disorder of maturation or terminal differentiation Low IgA Normal IgG and IgM ```
40
Hyper IgM syndromes (HIGM)
High IgM Low IgG, IgA Impaired Ig class switching and somatic hypermutation Susceptibility to bacterial infection Normal number of peripheral B cells but low memory B cells X-linked: due to mutation in the CD40L gene= MALE ONLY, 2/3 of cases of HIGM Autosomal C40 deficiency: FEMALE AND MALE 1/3 of HIGM
41
Isolated IgG subclass deficiency
Decreased concentrations of one or more IgG subclass Total IgG, IgM, IgA, IgE are normal Asymptomatic Low levels of IgG2 are frequent in children IgG4 levels vary widely and many healthy people hav no IgG4 Deficiencies may be associated with recurrent viral/bacterial infections, frequently involving the respiratory tract
42
Transient hypogammaglobulinemia of infancy
Low IgG/IgA Normal or low IgM Intrinsic Ig production is delayed for up to 36 months (normal usually begins immediately after birth) Increased susceptibility to sinopulmonary infections Normalize between 2-4 y.o.
43
Wiskott-Aldrich syndrome
X-linked recessive; decrease in T cells Defect in a cytoskeletal protein-Wiskott Aldrich Syndrome Protein (WASP) WASP expression is limited to cells of hematopoietic lineage Clinical manifestations: Thrombocytopenia Small platelets Platelet dysfunction Eczema Susceptibility to infections Low IgM IgG normal Elevated IgA and IgE Infants present with prolonged bleeding from the circumcision site, bloody diarrhea, and excessive bruising Recurrent infection by encapsulated bacteria At risk for autoimmune diseases and cancer
44
Complete B- and T-cell deficiencies
ADA-adenosine deaminase AIRE-autoimmune regulator APC-antigen-presenting cell Gamma c-common cytokine receptor gamma chain CIITA-MHC Class II transactivator DP-double positive IL-7R alpha- interleukin-7 receptor alpha chain JAK3-Janus kinase 3 PT alpha-pre-TCR alpha chain RAG-recombination-activating gene RFX-regulatory factor X TAP-transporter associated with antigen processing ZAP70- zeta chain-associated protein kinase
45
Severe combined immune deficiency (SCID)
Profound deficiencies of T and B-cell function (and sometimes NK) Severe lymphopenia Severe opportunistic infections—>chronic diarrhea and failure to thrive At risk abortion in pregnancy—>inability to reject the maternal T cells that cross into the fetal circulation (rare, not all cases) Rag1/2, ADA, and Artemis deficiencies are shared by both B- and T-cells
46
Deficiency in ADA in SCID
``` Progenitor cannot go to pro-cell B and T cells 16% of SCID T-B-NK- Purine salvage pathway issues ```
47
Deficiency in RAG1/2 and Artemis in SCID
Going from pro-cell to pre-cell Both B and T cells T-B-NK+ Problems with rearranging H chain in BCR and beta chain in TCR
48
Adenosine deaminase
Breaks down toxic products and makes them not toxic anymore | Progenitor—> pre-cell
49
Artemis
Involved in VJD recombination
50
T-B+NK+ SCID
IL-7R alpha chain deficiency | CD3 deficiency
51
T-B+NK- SCID
X-linked recessive SCID (gamma c deficiency) CD45 deficiency JAK3 deficiency
52
IPEX
Immnodysregulation, polyendocrinopathy and enteropathy X-linked syndrome Self-reactive T cells are not inhibited because of mutations in FOXP3—> loss of T-reg cells
53
Autoimmune lymphoproliferative syndrome (ALPS)
Death-inducing signaling complex (DISC) cannot form—>no apoptosis of T effector cells
54
X-linked lymphoproliferative syndrome (XLP)
Uncontrolled proliferation of T cells as a result in a mutation in a gene that encodes a signaling lymphocyte activation molecule
55
Common gamma chain deficiency (gamma c or IL-2R gamma)
``` Most common form of SCID X-linked recessive trait ONLY MALES T-B+ NK- Gene encodes gamma chain shared by the T-cell growth factor receptor (IL-2R gamma) No functional B cells since T cells are unable to help Opportunistic fungal infections Chronic diarrhea Skin, mouth, and throat lesions ```
56
Adenosine deaminase deficiency
``` AR trait: both boys and girls affected T-B-NK- Mutations in ADA gene Second most common cause of SCID ADA is essential for metabolic function of T cells Leads to accumulation of toxic metabolic by-products: adenosine and deoxy-ATP—>lymphocytes die Opportunistic fungal infections Chronic diarrhea Skin, mouth and throat lesions ```
57
Jak3 deficiency
``` SCID cause by mutation in a gene that encodes Janus kinase 3 (Jak3) Less than 10% of SCID T-B+NK- AR: boys and girls equally affected Causes defect in IL-2R signaling Opportunistic fungal infections Chronic diarrhea Skin, mouth, and throat lesions ```
58
DiGeorge Syndrome
Hypocalcemia arising from parathyroid hypoplasia, thymic hypoplasia, and malformation of outflow vessels of the heart Abnormalities during embryogenesis T-cell deficiency Hypocalcaemia—>tetany or seizures Deletion of 22q11 chromosome 10-25% of parents exhibits the 22q11 deletion but are nearly asymptomatic Facial abnormalities, major outflow tract defects of the heart, history of recurrent infections Susceptible to opportunistic infections: fungal, viral, protozoan, recurrent with intracellular bacteria
59
MHC Class I deficiency
Inability of TAP1 molecule to transfer peptides to ER CD8+ cells are deficient—>recurring viral infections CD4+ cells are normal Normal Ab production Normal DTH (delayed type hypersensitivity)
60
Bare lymphocyte syndrome
Rare recessive genetic condition NO MHC Class II expression on professional APCs Mutations in genes which encode for transcription factors that normally regulate the expression of MHC II genes Deficiency in CD4+ T cells Variable hypogammaglobulinemia (mainly IgA and IgG2) Recurrent infections and death in early childhood

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