Flashcards in Unit 2 + Cumulative Info Deck (71):
What is an MCV on a CBC and how can you calculate it?
MCV = Mean Corpuscular Volume = average volume of RBCs
-It's essentially a measure of size
MCV = (Hct/RBC)
What is MCH on a CBC and how can you calculate it?
MCH = Mean Corpuscular Hemoglobin = weight of hemoglobin in the average RBC
MCH = (Hgb/RBC)
What is MCHC on a CBC and how can you calculate it?
MCHC = Mean Corpuscular Hemoglobin Concentration = average concentration of hemoglobin in a given volume of packed cells
MCHC = (Hgb/Hct)
How can you differentiate the different WBCs on a peripheral smear?
--Neutrophils: acidophilic cytoplasm with fine granules, nucleus has clumped chromatin divided into 2-5 loves linked by thin filaments
--Lymphocytes: smaller with scant cytoplasm and a round nucleus with dense chromatin
--Monocytes: normally the largest cells, nucleus is irregular and lobulated, ample cytoplasm is grayish-blue
--Eosinophils: slightly larger than neutrophils, bi-lobed nucleus, spherical granules are larger, coarse and reddish orange
--Basophils: nucleus is obscured by coarse, purple-black granules
What is the least abundant WBC?
What transcription factor is most commonly activated in inflammation?
Name the cell that forms the bridge between innate and adaptive immunity.
Is Iron more soluble at a low or high pH?
Transferrin vs Ferritin
-Transferrin: transports iron through circulation, binds 2 Fe atoms at a time
-Ferritin: stores iron intracellularly, binds 4500 Fe atoms
Ways iron absorption can be depressed
-high gastric pH
Describe the structure and properties of hemoglobin.
-Tetramer made of 2 alpha and 2 beta globin chains with a heme group each
-Iron needs to be in Fe2+ (ferrous) form to bind oxygen
-Deoxygenated hemoglobin is in a taut confirmation due to salt bonds, hydrogen bonding, and hydrophobic interactions
-Once one oxygen binds hemoglobin changes to the relaxed configuration
-Allostery: substrate binding at one site on a protein leads to altered confirmation at other binding sites on the protein
-Positive Cooperativty: allosteric changes lead to increased affinity for substrate at the other binding sites
What can shift an oxygen dissociation curve and which way?
-Shift Left: High pH, low CO2, low DPG, low Temp
-Shift Right: low pH, high CO2, high DPG, high Temp
-Has Fe3+ (ferric iron) cannot carry oxygen, the curve shifts left, P50 goes down. Normally have 1% or less of methemoglobinemia.
-Blood is chocolate or brown in color.
-Can be due to congenital defects or acquired from drugs.
-Congenital Methemoglobinemia: Autosomal recessive, Cytochrome b5 reductase deficiency. Increased oxygen affinity at birth, blue and well at birth, asymptomatic heterozygote.
-Hemoglobin M: Autosomal dominant, mutation in alpha or beta chain making Fe3+ resistant to reduction, asymptomatic cyanosis, normal amount of hemoglobin with mild hemolysis, abnormal electrophoresis shows M band.
-Drugs: phenacetin, benzocaine, dapsone, sulfa, nipride, amyl nitrate, well water contaminated with nitrates. Level greater than 40% and symptomatic.
-TREAT WITH METHYLENE BLUE
What are the locations of hematopoeisis throughout human development?
-Yolk sac (3-7 mo)
-Liver (4 mos-birth)
-Bone marrow (birth-death)
How can you calculate bone marrow cellularity?
Cellularity (%) = 100 - Age of Patient
Antigen vs Immunogen
Despite the fact that all antigens are recognized by specific lymphocytes or by antibodies, not every antigen can evoke an immune response. Those antigens that are capable of inducing an immune response are said to be immunogenic and are called immunogens
What are the 5 classes of antibodies?
-most abundant in blood
-can pass through placenta to fetus
-comes up later than IgM after primary immunization, but levels go higher and last longer
-It takes 2 IgGs to activate complement
-first immuniglobulin made
-Decavalent because is a pentameric shape, but the shape rarely allows more than 2 of its 10 binding sites to interact with epitopes
-Best at complement because has 2 adjacent Fc's to begin cascade
-Large and viscous in solution so cannot make too much of it or it would slow down blood
-Does not move out of blood into tissue very well
-IgM is the only antibody made in the fetus
-made by plasma cells in lymphoid tissues near mucous membranes
-assembled into dimer by addition of Jchain while in plasma cell and then secreted into interstitial space
-IgA is exocytosed still bound to a receptor called the secretory component (SC). SC protects IgA from digestion in the gut
-works as our first line of immunological defense against invading organism
-transmitted in breast milk
only important role is as a B cell receptor
-its Fc adheres to mast cells and basophils
-triggers these histamine loaded cells and causes immediate hypersensitivity or allergy
-Important for resistance to parasites
Subclass vs Allotype vs Idiotype vs Anti-iodiotype
-Subclass: immunoglobulins are divided into subclasses because of slight differences in the amino acid sequences of their H chain C regions. IgG1, IgG2, IgG3, IgG4. IgA1, IgA2. IgM1, IgM2. IgD and IgE.
-Allotype: minor allelic differences in the sequence of immunoglobulins between individuals, determined by allotypes of your parents, useful in determining relatedness
-Idiotype: unique combining region, made up of the CDR amino acids of its L and H chain, that each antibody has.
-Anti-idiotype: antibodies made that recognize the unique sequence of that combining site.
Antibody Affinity Maturation
As you have hypermutation you get some B cells that are better and some that are worse. The ones that are better get activated more and are more likely to "stay in the race." Essentially the ones who get activated more stick around the and the ones that don't get activated as much fall out of the race. This leads to the body having better and better immunity to an antigen.
refers the tendency of one antibody to react with more than one antigen. Other antigenic determinants might also fit into the complementary-determining region (CDR) and if they did so detectably, we would say that the antibody cross reacted with those determinants. Example: if you immunize a person with cow pox, the antigenic determinants of small pox will also be recognized and the person will be immunized.
Germline vs Somatic Mutation in generating antibody diversity
-Germline: The individual V, D, and J segments that you are born with and the different combinations of those you can make
-Somatic Mutation: Alterations in DNA that occur after conception. Generated by variable (“sloppy”) V/J and V/D joining.
Describe allotypic exclusion and how B cells are made.
-The lambda, kappa and H chain gene families are all on different chromosomes. Each cell has 2 copies of each gene, but only 1 H chain (maternal or paternal) and 1 L chain (either kappa or lambda) are synthesized in any 1 B cell. All other genes are silenced. Though a person can make 2 allotypes, an individual B cell can only make 1.
-Immune system chooses: 1 heavy chain from either mum or dad and 1 light chain of which there are 4 options (mum kappa, dad kappa, mum lambda, or dad lambda).
Why do we write V(D)J instead of VDJ?
Because V and J are located on the light chain while D is located on the heavy chain.
Describe the sequence of appearance of cytoplasmic and surface immunoglobulins in developing B cells
-Pro B cell: cytoplasmic mu chains
-Pre B cell: a cell with cytoplasmic IgM but no surface IgM
-Immature B cell: a cell with surface IgM only and can interact with outside world. There is a ticking-clock amount of time that it remains an immature B cell before maturing. During this time the body looks to see if it binds to "self" by circulating things past the bone marrow. If it binds to "self" then the body either makes a new receptor or the cell will be aborted (clonal abortion). If it does not encounter self then it can mature further.
-Mature B cell: a cell with both IgM and IgD (of the same specificity) are on cell surface
How to distinguish maternal from infant antibodies.
-Mother's IgG starts getting produced when fetus is 3 months of age and is 100% of adult levels at birth. Steadily falls after birth. IgG has a half-life of 3 weeks and is completely gone around month 10.
-Baby's IgM starts getting produced at 3 months post-conception and continues rising through pregnancy and 1st year of life.
-Baby's IgG starts getting produced at 3 months post-birth.
Immune repertoire of young vs old people
-Have same number of immune cells
-Young people have more diversity than old people
-Old people have more copies of same immune cells
How can you distinguish the different types of T cells and B cells based on their surface markers?
-All T cells have CD3 (allows them to bind antigen and MHC)
-Helper T Cells have CD4 (have to use lymphokine production to distinguish between the types of Th)
-Cytotoxic T Cells have CD8
-B Cells have antibodies and CD20
Lymphokine vs Chemokine vs Cytokine
-Lymphokine: short range mediators made by lymphocyte that affects behavior of the same or another cell. A subset of cytokines.
-Chemokine: small (6-14 kD) short range mediators made by any cell that causes inflammation.
-Cytokine: short range mediators made by any cell that affects behavior of the same or another cell.
-Mitogen: non-specific protein that stimulates T cell and B cell division
Structure of T-Cell receptors
-Have an alpha and a beta chain each with a variable -region and constant region. Constant region is membrane spanning
-In thymus: T cell makes receptor out of V, (D), and J regions just like B cells
-Each chain has a CDR
How is a T-Cell turned on?
1. On the TCR is a complex of molecules called CD3. When T cell binds correct antigen + MHC with its TCR, the actual signal that turns the T cell on is transmitted by CD3.
2. When a Th0 binds to antigen-presenting cell, APC gives T cell boost by secreting IL-12. Needs these signals to be activated
Describe the two different MHC Markers and their purposes
-MHC Class II: dendritic cell, macrophage, and B cells (extrinsic pathway) (Th/CD4 focus on these)
-MHC Class I: all nucleated cells in body (including B cells, macrophages, and dendritic cell, NOT RBCs) (intrinsic pathway) (CTL/CD8 focus on these)
Cross Presentation of MHC Markers on Dendritic Cells
Cross Presentation: Dendritic cell shows foreign peptides on both MHC Class 1 and Class 2 receptors = makes them the best presenters = can stimulated both Th and CTL cells. Dendritic cell does not get sacrificed even though activates CTL.
Differentiate the role of Cytotoxic T-Cells and Helper T-Cells in clearing an infection
-CTL cells will “see” an infected/foreign cell (because MHC Class I will have it bound) and then will activate the target cell to commit suicide because it has a Fas CD95L Ligand (binds to Fas CD95 receptor on target cell) OR secretes lytic granules that trigger apoptosis.
-HELPER cells will “see” antigen presented on a dendritic cell, B cell or macrophage via MHC Class II. They will activate the immune response and divide.
Describe the characteristics of T‐independent antigens
-Most antigens require T cell help to achieve a reasonable antibody response, but some don’t. These are T-independent antigens are usually have the same epitope repeated over and over (rare in proteins, but common in carbohydrates, ie: Streptococcus pneumoniae). Carbohydrate chain binds to the B cell antibodiesà cell is activated and begins to divideà The response to T-independent antigens is almost all IgM (T cells needed to switch from IgM to IgG, IgA or IgE). So, if a person is very deficient in T cells, they still have make antibody to carbohydrates. With protein antigen—NO IgM and NO IgG is made without T cell help
Describe repertoire selection in the thymus
-Stromal cells in Thymus specialized for this selection process. If born without thymus = no T cells.
-Thymocytes migrate from bone marrow to thymus. Have an alpha and beta chain on receptors. Alpha is made of VJ alpha and Beta is made of VDJC beta (not located on same chromosomes as B cells).
-These cells migrate from out to in (medulla) of thymus. Hard to make it to the medulla.
-Rules are have to be able to recognize MHC marker, but not self-peptides. Each arm of the T cell receptors has 3 CDRs (complemetarity determining regions) aka each alpha and beta chain has 3 fingers (fingers 1 and 2 bind MHC, and finger 3 binds antigenic peptide) (fruit bowl example)
-Not all peptides will show-up in thymus (ie stuff that lives in the gut) so have special transcription factor in stromal cells called AIRE that code for 70,000 proteins to show them to T cells so that they don't kill self
Differentiate between positive, negative, and non-selection of T-Cells in the thymus
-Negative selection: 6/6 receptors bind with high affinity during test phase in thymus. This makes them self-reactive so body tells them to go through apoptosis. If they do not bind with as high of affinity they can be used as Treg cells.
-Positive selection: 4/6 receptors bind (bind MHC, but not self-cell means that they may bind foreign antigen) they get to go on and be developed.
-Non-selection: none of the 3 CDRs bind very well so cell is told to go through apoptosis because it cannot recognize self.
What are the genes that encode for MHC Class I and MHC Class II markers?
MHC = Major Histocompatibility Complex
-MHC in humans is called HLA (Human Leukocyte Antigen)
-HLA-A and HLA-B are genes that encode for Class I MHC
-HLA-D is the gene that encodes for Class II MHC
What is the most important gene related to MHC Class markers for transplant patients?
-If the donor and recipient are identical at HLA-A and HLA-B, but different at HLA-DR: you will activate Th1, but no CTL will be generated. You will still reject the graft but since only Th1 and not CTL are involved, rejection will be slower.
-If the donor and recipient are different at HLA-A and HLA-B, but identical at HLA-DR, you will get no MLR/no Th1 activation/no IL-2 generation and few CTL will be activated. Only a few CTL are activated because Th1 won't be producing IL-2 to encourage CTL to proliferate. Therefore, a good HLA-DR match is the most important.
Alloantigen vs Haplotype
-Alloantigen: antigen that is a part of an animal's self-recognition system. e.g., Major histocompatibility complex molecules. When injected into another animal, they trigger an immune response aimed at eliminating them. Therefore, it can be thought of as an antigen that is present in some members of the same species, but is not common to all members of that species. If an alloantigen is presented to a member of the same species that does not have the alloantigen, it will be recognized as foreign.
-Haplotype: combination of alleles (DNA sequences) at adjacent locations (loci) on the chromosome that are transmitted together. Get one half of intact MHC from father's haplotype and one half of intact MHC from mother's haplotype. Example: Father (D5B27A15/D2B17A6) and Mother (D3B7A1/D4B6A3) yields Child (D5B27A15/D4B6A3)
What is a one-way mixed leukocyte reaction (MLR) and why is it used?
-To answer the question: How strongly do the recipient’s T cells recognize the Class II of this potential donor versus that one?
-Cells from the donor are treated with DNA synthesis inhibitors or radiation (kills lymphocytes, but not APCs like macrophages) to prevent their division. You want to know if the recipient can recognize the donor’s MHC. Then the cells from donor and recipient are mixed together to see if recipient’s Th cells divide in response to the donor’s HLA-D (mostly DR, on monocytes). A strong reaction (burst of cell division) may preclude the transplant.
Hyperacute Graft Rejection
In hyperacute rejection graft tissue is rejected almost immediately because there was circulating antibody against the graft’s tissue (from a previous failed graft) or against the graft’s residual blood in the tissues endothelium. The antibodies attached to endothelium and activate lots and lots of complement: anaphylatoxin (C3a, C4a, C5a) from mast cells and vasospasm, constricting vessels and tissue ischemia. COMPLEMENT MEDIATED IS FAST REJECTION.
Humoral vs Cell-Mediated Immunity
i. Inhibits binding to host cells (prevents entry)
ii. Promotes uptake by macrophages
iii. Lysis (complement)
iv. Most effective against extracellular pathogens
i. Destroy pathogen (neutrophils, activated macrophages)
ii. Inhibit growth (interferons)
iii. Kill infected cells (cytotoxic T cells)
iv. Most effective against intracellular pathogens
-Current vaccine efficacy is almost exclusively dependent on humoral/antibody immunity
What are the three types of vaccination?
1. Live attenuated vaccine
2. Whole killed virus/bacteria vaccine
3. Subunit vaccine
Live attenuated vaccine
=weakened live virus
-all aspects of innate immunity engaged
-robust cellular (CD4 and CD8) and humoral response
-longer lasting humoral response with higher titter and affinity
-higher risk of adverse events including reversion to virulence
-increase contraindication in the population
-production cost and stability-cold chain
-not all infections can be attenuated
Example: MMR, smallpox
Whole killed virus/bacteria vaccine
-endogenous ligands produce robust innate activation
-strong humoral response indicative of good CD4 T cell help
-higher risk of adverse events, strong local toxicity. "Reactogenicity."
-substantial loss of CD8 response
-production cost and stability
Example: rabies, polio
=using only components, or subunits, of the infectious agent in vaccine formulation
-sufficient humoral response
-fewer reactogenicity/toxicity issues
-lower production cost and increased shelf life
-little to no cellular response. CD4 responses inferred by class switching
-requires more frequent boosting
-requires adjuvant - dramatically reduced innate activation
Example: HPV, pneumococcal, influenza
Why do some live viral vaccines tend to be ineffective in the very young?
Some live viral vaccines tend to be ineffective in the very young because the baby would still have mom's IgG so the baby's immune system would not generate a response, mom's would.
When do children get the DTaP vaccine?
2, 4, 6, and 15-18 months
When do children get the polio vaccine?
2, 4, and 6-18 months
When do children get the MMR vaccine?
12-15 months and 4-6 years
Salk vs Sabin Polio Vaccine
Salk Vaccine (Used in US)
i. High safety
ii. Induces protective IgG
iii. No IgA formed in gut
iv. Virus still replicates in host and can spread to others
v. Protection is short lived…no cellular immunity
vi. Given IM
i. Live infection in gut. Forms both cellular and humoral immunity so longer lived
ii. Forms protective IgA so blocks spread of WT polio
iii. Vaccine strains shed from host and can provide "herd" immunization
iv. Reversion to virulence leads to high incidence of latrogenic infections
v. Have some cases of vaccine associated polio
vi. Given orally
a substance that enhances the body's immune response to an antigen. Best induces adaptive immunity.
Explain the production, distribution, and turnover rate of neutrophils.
i. Produced in marrow, storage pool for host defense (10-14 days). Released into peripheral blood (6 hr.), then move to tissues. Turnover 1-2 days.
ii. Major component of innate immune system: non-specific defense against microbes. Important response to tissue injury.
Explain the production, distribution, and turnover rate of eosinophils.
i. Produced in bone marrow under influence IL-5.
ii. Morphologic features, mitotic and storage pool like neutrophils.
iii. Mature cell 12-14 micron dia. Large “eosinophilic” granules, bi-lobed nuclei.
iv. Released into peripheral blood, move to external surfaces (tracheobronchial tree, GI tract, etc.). Survive for weeks.
v. Can function as phagocyte.
Roles allergies, parasite infection, response to tumors: may be immuno-enhancing or immuno-suppressive.
Explain the production, distribution, and turnover rate of basophils.
i. Very few number of them
ii. Produced in bone marrow, released in peripheral blood (seen infrequently), move to tissues.
iii. Similar in size to eosinophils, bi-lobed nucleus, prominent primary granules (blue/purple).
iv. Receptors for IgE.
v. Function: pathophysiology hypersensitivity reactions (allergic).
Explain the production, distribution, and turnover rate of monocytes/macrophages.
i. Shorter time in marrow (7 days). Released after last mitotic division (no storage), days in intravascular compartments (3-5 days), then move to tissues (days-months).
ii. 10-18 micron dia. Gray cytoplasm indented (kidney shaped) nucleus. Morphology changes in tissues.
iii. Function: a) Move to sites of infection and inflammation; b) Filter function; c) Processing and presenting antigens; d) Clearance of apoptotic cells and debris.
=Decrease in the absolute neutrophil count (include bands and segmented polymorphonuclear leukocytes) below accepted norms for age and other considerations.
-Neutropenia implies decrease delivery of neutrophils to tissues → tips balance in favor of bugs and inability to localize and resolve bacterial and fungal infections. Possible life-threatening consequences.
-Treatment: treat underlying condition, replace deficiency, aggressive management of infections, supportive care, and may give G-CSF. May do a bone marrow transplant if there are severe complications
What is leukocytosis?
-Leukocytosis: An ↑ in total white blood count beyond norms: always concern for infection, inflammation, stress, or malignancy (leukemia).
What is a "left shift"?
-Left Shift: a term which describes changes in a normal white blood cell differential characterized by an increase in neutrophils (segs and bands).
Leukocyte Adhesion Deficiency
-Neutrophils cannot adhere to endothelial surface and thus cannot get out of the blood flow and into the infected tissue
-Deficiency of CD18
-Recurrent soft tissue infections and delayed detachment of umbilical cord
-Granule defect disorder
-partial or complete deficiency of myeloperoxidase which results in a mild defect in killing bacteria and a significant defect in killing candida infections
-Post-translational modification defect
-Individuals are generally healthy, but may have problems clearing fungal infections
-Granule defect disorder
-Neutropenia. Major defect in movement of neutrophils and with degranulation.
-mutation on CHS gene
-causes systemic effects including oculocutaneous albinism, nystagmus, photophobia, recurrent infections, hemophagocytic disorder, neurodegenerative as adult
Chronic Granulomatous Disease
-Neutrophilia. Normal adherence, chemotaxis, ingestion, and degranulation. Defect in oxidase enzyme system which results in problem killing things.
-4 different types of mutations
-Over half of patients it is X-linked recessive and the rest it is autosomal recessive
-Recurrent infections, especially involving skin and mucous membranes. Can also get deep infections in lungs, liver, spleen, lymph nodes, and bones.
NADPH Oxidase Enzyme System
-It is a membrane-bound enzyme complex. Under normal circumstances, the complex is latent in neutrophils and is activated to assemble in the membranes during respiratory burst. The system generates superoxide by transferring electrons from NADPH inside the cell across the membrane and coupling these to molecular oxygen to produce superoxide (a reactive free radical).
-Can test if it is working by Nitro blue tetrazolium chloride (NBT dye reduction test) which will turn blue when working OR a Dihydrorhodamine (DHR) test.