[WinFlash] Q1=Explain the general roles of the leukocytes that mediate immune responses. A1=Phagocytic (non-specific) cells present antigens for recognition by the immune cells which clear infections. ^Helper T cells recognize the antigens presented by the macrophages and activate the responding leukocytes. ^Cytotoxic T cells participate in cell-mediated killing upon helper T cell activation. ^B cells produce antibodies in response to helper T cell activation and are the humoral-response cells. Q2=Explain the three different phases of an immune response. A2=1) Recognition phase - specific helper T cells recognize the antigen presented by macrophages ^2) Activation phase - helper T cells then activate both T and B cells ^3) Effector phase - response by cytotoxic T cells and B cells, whereby the pathogen is attacked and cleared Q3=Define antigen and the five other terms related to antigen (carrier, immunogen, hapten, determinant, epitope). A3=Antigen - foreign molecules; especially proteins and carbohydrates ^Carrier = Immunogen - larger molecules that are able to elicit an immune response ^Hapten - molecules which can bind to an antibody, but can't elicit an immune response alone (require carrier) ^Determinant - conveys information about how complex an antigen is ^Epitope - the specific part of an antigen which is bound by an antibody Q4=Describe the four characteristics that differentiate immune responses from other biological systems. A4=Diversity - recognition of a very large number distinct antigens ^Memory - aka secondary response; faster response upon second exposure ^Specificity - binding to unique epitope better than almost any other epitope by more than a million fold ^Tolerance - the immune system may become unresponsive to various antigens (especially self-antigens) Q5=What are the names of the polypeptides that make up an immunoglobulin molecule? A5=Heavy chain (44-55 kD) - alpha, delta, epsilon, gamma, and mu ^Light chain (24 kD) - kappa and lambda Q6=Define the difference between a constant and variable region of an immunoglobulin. A6=Constant region - segment of an antibody polypeptide which never changes ^Variable region - segment of an antibody polypeptide which is never the same between antibodies which bind different epitopes Q7=Explain how an immunoglobulin domain is defined, the basic 3-dimensional structure of an immunoglobulin domain, and how domains are put together to form the immunoglobulin protein. A7= Q8=Define the difference between a framework and complementarity determining (hypervariable) region. A8=Both the framework and hypervariable regions are part of the variable region of the immunoglobulin and are inherently variable. Within each variable region, there are three hypervariable regions which consist of ~7 amino acids that are especially variable. There are four framework regions in each variable region that do possess some variability, but not nearly to the extent of the hypervariable regions. Q9=Explain how the structure of a complementarity determining region relates to its function in antigen binding. A9=When the variable regions fold into the proper tertiary structure, the three hypervariable regions are brought into close proximity to one another to allow binding of these hypervariable regions to the antigen. Q10=Describe the different functions of the different antibody classes and subclasses. A10=IgG - some fix complement; cross placenta ^IgA - secreted at mucosal surfaces ^IgM - complement fixation; opsonization ^IgD - cell surface only ^IgE - binds mast cells; allergies; low concentration because of high affinity ^(in decreasing order of abundance) Q11=Describe the principles and application to clinical medicine of the following immunological tests: radioimmune assay (RIA), enzyme linked immunosorbent assay (ELISA), and Western blots. A11=RIA - binding of antigen and competitors to fixed antibody ^ELISA - detection of either antibody or antigen ^Western - antibody binding to denatured protein after being separated by electrophoresis Q12=Define the mechanisms by which the complement system is activated and regulated. A12=Activation by three pathways all lead to C3 convertase formation: ^Classical - antibodies provide targeting specificity ^Lectin-binding - relies on binding to mannose residues found on bacterial surfaces ^Alternative - relies on non-specific binding; host protected using regulatory proteins on surface ^- ^Amplification = conversion of C3 to C3a and C3b by C3 convertase Q13=Define the effector molecules of complement activation. A13=1) Classical - C1 + Fc = C1q - - C1q + C4 + C2 = C4b2b (C3 convertase) {C4 binds surface} ^2) Lectin-binding - MBP + C4 + C2 = C4b2b (C3 convertase) {C4 binds surface} ^3) Alternative - C3 + P + B + D = C3bBbP (C3 convertase) {C3 randomly binds surface} Q14=Describe the role of complement in bacterial clearance and lysis. A14=Binding of complement serves two main functions: ^1) Formation of the membrane attack complex by C5b-C9 cascade, which leads to cell lysis ^2) Opsonization - C3b and C3bi (a C3b degradation product) promote phagocytosis ^- ^Another function of complement is due to by-products of the complement cascade known as anaphylatoxins: C3a and C5a; C2a and C4a to a lesser extent. ^- ^Anaphylatoxin functions: ^1) Mast cell degranulation ^2) Smooth muscle contraction ^3) Increased vascular permeability ^4) C5a is a chemotactic agent for phagocytic cells Q15=Describe the effects of specific complement deficiencies on patients. A15=Deficiencies in early components (e.g. C1, C2, and C4) leads to auto-immune disease. ^Deficiencies in later components (e.g. C3) leads to increased risk of infection from particular bacteria. ^- ^C1INA = hereditary angioedema; uncontrolled C2 activation with C2a (anaphylatoxin) production. ^DAF or protectin deficiency = paroxysomal nocturnal hemoglobinuria Q16=Describe the use of plasma CH5O levels in the assessment of disease processes. A16=CH50 = dilution of serum which results in 50% complement hemolysis ^Low dilution (e.g. 1/50) indicates complement depletion due to high complement activity. Q17=What are the two fundamental stages of B cell differentiation? A17=Antigen-independent ^Antigen-dependent Q18=Describe the steps in antigen-independent B cell differentiation. What landmarks define the steps? How does B cell function and diversity change at each step? A18=Multipotent stem cell - ^Pro B cell - B220/CD45R ^Pre B cell - mu chain and a surrogate light chain (VpreB + lambda-5) [checkpoint] ^Immature B cell - IgM [self-checkpoint by clonal deletion] ^Mature B cell - IgM and IgD (exact same antigen binding domain) Q19=What tools are used to identify different steps of cellular differentiation (including B cell differentiation)? A19=Flow cytometry a.k.a. FACS (flow-aided cell sorting) Q20=What are the basic molecular changes associated with B cell activation during antigen-driven B cell differentiation? A20=Cell division ^Morphological changes by differentiating into plasma cells ^Antibody secretion ^Affinity maturation ^Class switching Q21=What external factors are required for antigen-dependent B cell differentiation? A21=Surface antibodies close together, promoting signaling through the associated Ig-alpha and Ig-beta proteins. ^T cell help is required for B cell differentiation Q22=What are basic features of a multiple myeloma? A22=Monoclonal plasma cell tumor ^Single clone characteristics, such as one primary antibody produced ^Stage-specific tumor of B cell lineage ^Affects other marrow cells Q23=What are some of the features of multiple myeloma that aids in its diagnosis? A23=Single antibody can be detected by electrophoresis ^Urinalysis for immunoglobulin protein (Bence-Jones) Q24=What do T cells recognize as ligands to initiate an immune response? A24=T cells recognize peptide antigens presented by MHC. Q25=What are the two major roles of MHC in T cell mediated immunity? A25=1) T cells only recognize antigens presented by the MHC. ^2) MHC molecules are involved in forming the mature T cells in the thymus. Q26=What are the structural and functional differences and similarities between major classes of MHC gene products? A26=MHC CLASS I ^function: ligands for CD8 cytotoxic T cells ^structure: alpha1-3; beta2-m ^peptide binding: alpha1-2 ^- ^MHC CLASS II ^function: ligands for CD4 helper T cells ^structure: alpha1,2; beta1,2 ^peptide binding: alpha1 and beta1 Q27=What are the genetic characteristics of MHC? A27=Polymorphic (HLA-A1 vs. HLA-A2) [exception: HLA-DRalpha is monomorphic] ^Polygenic (HLA-A, -B, -C) ^Co-dominant expression (both alleles are expressed) ^- ^MHC class I: one gene for each HLA-A, -B, and -C ^MHC class II: one alpha gene for each HLA-DR, -DQ, and -DP ^MHC class II: one beta gene for each HLA-DQ and -DP; two beta genes for HLA-DR Q28=What is the significance of MHC in medicine? A28=Infection ^Cancer (one way cancer can evade immune system is down regulate MHC expression) ^Autoimmunity (correlation of the HLA haplotype with autoimmune diseases) ^Transplantation - graft rejection (allo-reactivity) Q29=What is the main difference of the ligand for CD4 and CD8 T cells? A29=CD4 T cells recognize peptide originating in the vesicular system presented by MHC class II ^CD8 T cells recognize peptide originating in the cytosol presented by MHC class I Q30=How are exogenous protein pathogens (e.g. bacteria) presented? Which molecules are key players for processing and presentation? A30=MHC class II is found only on professional APCs. ^MHC class II presents exogenous sources of antigens to CD4 T cells. ^MHC class II are synthesized in the ER and transported to the endosome by the invariant chain (Ii). ^CLIP is the portion of Ii that binds to three MHC class II molecules and remains fused within acidic vesicles. ^Peptides are loaded in the endosome by HLA-DM, which is able to remove CLIP from the binding site. Q31=How are endogenous protein antigens (e.g. virus) presented and which molecules are key players for processing and presentation? A31=MHC class I is found on all nucleated cells. ^MHC class I presents endogenous sources of antigens to CD8 T cells. ^Polypeptides are degraded in the proteasome and the resultant peptides are transported to the ER by TAP. ^MHC class I assembly requires calnexin, calreticulin, and tapasin before the peptide is loaded in the ER. ^Fully folded MHC class I is transported to the cell surface through secretory pathways. Q32=What could be the consequence of a defect(s) in antigen processing and presentation pathway? A32=Can't initiate T cell mediated immune response. ^T cells can't develop. Q33=What does TCR look like? Is the TCR structure similar to that of immunoglobulin? A33=TCR looks like the membrane bound Fab fragment of immunoglobulin. Q34=What are the two major subsets of alpha-beta T cells and what is the main cell surface molecule to distinguish these subsets? A34=CD4 T cells ^CD8 T cells Q35=What are co-receptors and what do they recognize? What is the function of the co-receptor? A35=CD8 is a co-receptor which recognizes MHC class I ^CD4 is a co-receptor which recognizes MHC class II ^The interaction between CD4/CD8 with MHC enhances the binding of T cells to the APCs. ^CD4 and CD8 also function as signaling molecules. Q36=What are superantigens? What is the fundamental difference between the superantigen mediated activation of T cells compared to that of MHC peptide? A36=Superantigens are produced by many different pathogens. ^Superantigens bind directly to the outer surface of both the MHC class II and the Vbeta region of the TCR. ^Binding by the superantigen activates the T cells. ^Superantigens are inactivated upon processing; native form is required for correct binding. Q37=What is the CD3 complex and what does it do? A37=The CD3 complex is composed of multiple non-polymorphic proteins (e.g. gamma, delta, epsilon, etc.). ^The CD3 complex is involved in signaling and TCR transport to the cell surface. Q38=What do T cells require to become mature T cells in the thymus? A38=CD4 T cells require the MHC class II-peptide complex to be expressed in the cortical thymic stromal cells. ^CD8 T cells require the MHC class I-peptide complex to be expressed in the cortical thymic stromal cells. Q39=What is the developmental pathway of thymocytes? A39=DN (CD4-CD8-); immature thymocytes ^DP (CD4+CD8+); intermediate thymocytes ^SP (CD4+ OR CD8+); mature thymocytes which exit to the periphery Q40=What is positive and negative selection of T cells? A40=POSITIVE SELECTION ^T cells bearing TCR that are partially signaled by self-MHC with peptides are rescued from apoptosis and mature. ^- ^NEGATIVE SELECTION ^T cells recognizing self-peptide bound to self-MHC with high avidity are deleted by apoptosis. Q41=Why is T cell selection important and what is the consequence of dysregulated T cell development? A41=Selection enables appropriate immune responses by SP T cells. ^- ^Dysregulated T cell development can lead to lymphoproliferative disease or autoimmunity. Q42=What are three possible outcomes when a T cell engages the ligand? A42=1) Proliferation, differentiation, and clonal expansion ^2) Tolerance and anergy without co-stimulation ^3) Death due to over-stimulation (a.k.a. AICD) Q43=What is the major difference in the requirement of naive vs memory T cells to proliferate? A43=Naive T cells require two signals: ^1) TCR conveys specificity ^2) Co-stimulation for signaling ^- ^Memory and effector T cells do not require co-stimulation. Q44=What are the co-stimulatory molecules for T cell activation? A44=Co-stimulatory molecules, such as B7.1 and B7.2 are the cell surface molecules on professional APCs. They are required for proper activation of naive T cells. In the absence of co-stimulatory molecules, T cells will be anergized or tolerized. Q45=What is activation induced cell death (AICD) and which cell surface molecules are involved in this process? A45=AICD is death due to over-stimulation. ^Fas and FasL are the molecules which are involved. Q46=What is the significance of AICD in the maintenance of homeostasis of the immune system? A46=AICD is necessary for elimination of activated T cells after the antigen has been cleared. Q47=What is CTLA-4 and what is it used for? A47=CTLA-4 is an inhibitory molecule found on T cells which binds B7 with higher affinity than CD28. CD28 binding to B7 stimulates CTLA-4 expression, resulting in a feedback pathway. Q48=What are the major functions of humoral and cell-mediated immunity? Which subset of effector CD4 T cells regulates these immune responses? A48=CELL-MEDIATED ^Th1 CD4 T cell mediated ^Promotes macrophage activation ^Cytotoxicity ^Delayed type hypersensitivity ^Th0 to Th1 stimulated with IL-12 or IFN-gamma ^- ^HUMORAL ^Th2 CD4 T cell mediated ^Helps B cell, eosinophil, and mast cell stimulation. ^Promotes macrophage deactivation ^Th0 to Th2 stimulated with IL-4 Q49=What are the initial requirements to direct naive CD4 T cells to become fully differentiated effector cells? A49=MHC-peptide ^Co-stimulation ^Cytokines (IL-12 = Th1 and IL-4 = Th2) Q50=What are the major cytokines produced by T helper subsets? A50=Th1 = IL-2, IFN-gamma, TNF-alpha ^Th2 = IL-4, -5, -6, -10, -13 Q51=How do cytotoxic T cells kill infected cells? A51=1) Causing apoptosis because of interactions between Fas and FasL ^2) Causing cytolysis using perforin and granzymes Q52=What could be the consequence of dysregulation of cytokine production by effector T cells in the immune system? A52=1) Leads to many immune diseases including auto-immune diseases ^2) Leads to a lack of differentiation of the proper effector T cells Q53=Are there any other effector cells besides B cells and cytotoxic T cells which can mediate an immediate immune response? If so, what are they? A53=Natural killer cells ^NK1 (NK1.1+) T cells ^gamma-delta T cells Q54=What is the major function of NK cells and what do they recognize? A54=The major function of NK cells is killing infected cells by recognizing cell surface molecules (MHC class I ligand, NK cell receptor ligand) expressed on target cells. Q55=What are the similarities and differences between cytotoxic T cells and NK cells in their recognition of target cells and the killing mechanism? A55=NK cells function by killing MHC class I negative target cells. ^NKR-P1 recognizes self-carbohydrate expressed on the self cells and sends a killing signal if the target cells fail to express MHC class I. ^- ^In cytotoxic T lymphocytes, killing requires the recognition of MHC class I-peptide on the target cells. FasL recognizes Fas and sends a killing signal. Q56=What is the major function of NK1 T and gamma-delta T cells? A56=The major function is to serve as the first line of defense. ^NK1 T cells: produce cytokines which mediate T helper cell differentiation Q57=What does non-classical MHC present? A57=Non-classical MHCs are CD1 and MIC and they present non-peptide antigens. ^CD1 presents lipid and glycolipid. ^MIC presents an unknown antigen. Q58=What is the main difference between an early non-adaptive vs an adaptive immune response? A58=EARLY NON-ADAPTIVE ^Rapid and the outcome of this response induces the adaptive immune response. ^- ^ADAPTIVE ^Slow and requires B and T cell interaction, but is important for protective immunity. Q59=Why is production of monoclonal antibodies by hybridomas so useful? A59=Immortal cell lines ^Monoclonal, therefore specific ^Hybridomas can be grown in large quantities Q60=How is it possible for a human to express more than ten million antibodies or T cell receptor molecules? A60=Germline diversity - hundreds of V regions, several D regions, and four J regions ^Combinatorial diversity - joining any V to any D to any J ^Junctional diversity - variation in the crossover point and variable NT removal by nucleases ^N regions - nucleotides added by terminal deoxynucleotide transferase are randomly chosen Q61=How are the genes for antibody and T cell receptor variable regions organized? A61=All V regions are linked in tandem, each preceded by its own L region. ^Downstream from the V regions are the D regions, followed by the J regions, followed by the C regions. Recall the D regions are not present in light chains. ^The L, V, D, and J regions are all present as a single segment or exon. ^The C segments are divided into four exons. Q62=How is diversity in the germline further expanded by somatic DNA rearrangement? A62=Combinatorial diversity - joining any V to any D to any J ^Junctional diversity - variation in the crossover point and variable NT removal by nucleases ^N regions - nucleotides added by terminal deoxynucleotide transferase are randomly chosen Q63=What is the biological mechanism that allows only one of the two alleles of an immunoglobulin or T cell receptor gene to be expressed? A63=1) rearrangement to form the heavy chain VDJ ^2) if no mu is formed, switch to the other chromosome ^3) if there is a mu produced, heavy chain recombination stops (pre-B cell stage) ^4) light chain recombination then occurs, with Vkappa to Jkappa joining being more common than lambda ^5) without proper light chain formation, other chromosomes are sampled ^6) with proper light chain formation, IgM is formed and recombination stops (immature B cell stage) ^[note: only 5% of pre-B cells become immature B cells] Q64=What tumors represent various stages of B cell differentiation? A64=Acute lymphoblastic leukemia - lymphoid progenitor with DJ rearrangement ^Pre-B cell leukemia - mu is in the cytoplasm and there is VDJ rearrangement ^Chronic lymphocytic leukemia - heavy and light chain rearrangement with IgM ^Follicular center cell lymphoma/Burkitts lymphoma - mature B cell with IgM ^Waldenstroms macroglobinemia - IgM-secreting B cell ^Multiple myeloma - plasma cell tumor Q65=How can VDJ junctions be used in diagnosis of tumors? A65=B cells won't rearrange at the T cell locus and T cells won't rearrange at the B cell locus. Therefore, look at both loci to see which is rearranged. CDR3 is commonly used for diagnosis. Q66=How can IgM and IgD be expressed simultaneously on the surface of a mature, but naive, B cell? A66=The selection of the constant region is mediated by RNA splicing. ^The result is that both IgM and IgD will have the same VDJ region, while having a distinct C region. Q67=What are the cellular and molecular interactions that lead to antigen-driven B cell differentiation. A67=Mutual activation of the T cell and B cell by: ^1) TCR (T cell) : peptide-MHC class II (B cell) interactions ^2) CD40 ligand (T cell) : CD40 (B cell) interactions ^3) cytokine secretion from T cells Q68=What are the two types of T cell help? A68=Th1 ^Cell-mediated immunity ^Intracellular pathogens ^Macrophage activation ^IFN-gamma, IL-2, TNF-beta ^- ^Th2 ^Humoral immunity ^Extracellular pathogens ^Eosinophil and mast cell stimulation ^B-cell help ^Macrophage deactivation ^IL-4, -5, -6, -10, -13 Q69=What is the mechanism of the heavy chain isotype switch? A69=DNA deletion Q70=How can antibody V genes further diversify during antigen-driven B cell differentiation? A70=Somatic hypermutation - only in rearranged immunoglobulin genes Q71=What type of behavior in leukocytes is stimulated by selectins? A71=Rolling on vascular wall Q72=What type of ligands bind selectins? A72=Sugars Q73=What modification is necessary to activate selectin ligands? A73=Glycosylation Q74=What is the general structure of an integrin? A74=Heterodimer of an alpha (14 possible) and a beta (9 possible) subunit Q75=What are some integrin-integrin receptor pairings? A75=beta2 : ICAM ^alpha4-beta1 (VLA4) : VCAM ^alpha4-beta7 (Peyers patch) : MadCAM, VCAM Q76=What type of behavior is stimulated by integrins? A76=Arrest on vascular wall Q77=What effects do TNF and IL-1 have on leukocytes? A77=Stimulate leukocyte recruitment ^(especially out of vasculature and into tissue) Q78=What are the major enzyme systems involved in the metabolism of arachidonic acid? A78=Phospholipase A and C ^Cyclooxygenase 1 and 2 ^Lipoxygenase Q79=What are the major inflammatory mediators derived from the metabolism of arachidonic acid? Define their cellular source and describe their biological activity. A79=AAC METABOLITE SOURCE ACTIVITY(IES) ^Leukotriene B4 (LTB4) PMNs promotes phagocyte chemotaxis ^Thromboxane A2 (TXA2) Platelets induces platelet aggregation and vasoconstriction ^ Leukotrienes (LTC4, LTD4, LTE4) Mast cells induces smooth musc contrac and inc vasc perm ^Prostacyclin (PGI2) Endothelial cells inhib platelet aggreg and vasodil;suppress inflam activ ^Prostaglandins (PGE2) Macrophages inhib platelet aggreg and vasodil;suppress inflam activ Q80=How do non-steroidal anti-inflammatory compounds block the production of arachidonic acid metabolites? A80=NSAIDs block cyclooxygenase, which prevents prostaglandin release. ^Aspirin covalently inhibits ^Ibuprofen et al are competitive inhibitors Q81=How does aspirin therapy work as an anti-thrombogenic agent? A81=Aspirin therapy works by inactivating cyclooxygenase in platelets and endothelial cells. Only endothelial cells are able to re-synthesize new cyclooxygenase, so coagulation related to platelets is reduced. Q82=How do diets rich is fish (containing high levels of omega3 fatty acids) potentially lower the incidence of cardiovascular disease? A82=Derivatives of omega-3 fatty acids are less able to initiate clot formation. ^Prostacyclin-mediated clot formation remains unchanged. ^Therefore, ingestion of omega-3 fatty acids resembles low-level aspirin use. Q83=What are some of the major physiological activities of cytokines and how are these related to symptoms of disease? A83=Circadian temperature rhythms fever ^ Sleep regulation lethargy ^ Appetite regulation appetite loss Q84=What are some of the diverse biological activities of cytokines, and in particular IL-1, which are evident during inflammation?. A84=GENERAL ^Recognition/Activation ^Recruitement/Elicitation ^Pathogen removal ^Resolution/Repair ^- ^IL-1 ^Alters physiology ^Mobilizes leukocytes ^Alters liver metabolic processes ^Mobilizes insulin and glucagon release ^Activates endothelial cells ^Activate lymphocytes Q85=Describe some of the biological activities of chemokines on neutrophil function. A85=1) Chemotactic attractant ^2) Leukocytic activation Q86=How do specific chemokine receptors participate during HIV-1 entry into macrophages and lymphocytes? A86=CCR5 (monocyte) and CXCR4 (T-cell) are co-receptors for HIV infection. ^The attachment of HIV to co-receptors is necessary for infection. Q87=What is the pathophysiologic role of phagocytic cells in host defense? A87=1) Phagocytosis ^2) Oxidant production ^3) Lysosomal granules ^4) Cytokine secretion Q88=What is the role of reactive oxygen metabolites and lysosomal granules in phagocytic cell function? A88=Binding of the C3b or Fc receptors on phagocytes leads to phagocytosis. Reactive oxygen species and lysosome degranulation serves to kill pathogens in the phagosome. Q89=What is the role of IgE-mediated mast cell degranulation in Type I reactions? A89=Degranulation leads to a release of histamine, chemotactic factors, and proteases. Q90=What are the primary effector mediators released during mast cell stimulation? A90=Histamine ^leukotrienes ^PAF ^PGD2 ^chemotactants ^cytokines Q91=What are the pathologic changes observed in tissues associated with anaphylactic hypersensitivity reactions? A91=Histamine causes local vasodilation, increase vascular permeability, bronchial and smooth muscle contraction, which leads to airway narrowing and GI pain, vomiting, and diarrhea. Presents as EDEMA, decreased FEV, pruritis (itching), and urticaria (hives). Q92=Why is there a modulatory role of eosinophils in anaphylactic hypersensitivity reactions? A92=Eosinophils possess multiple enzymes necessary for moderating anaphylactic hypersensitivity reaction effects: histaminase, arylfulfatase, PGE, LTC4, major basic protein, NADPH oxidase-derived oxidants, and lysophospholipase. Q93=Describe the effect of mediators on target organs with the clinical expression of anaphylactic reactions. A93=Allergic rhinitis or bronchial asthma - inhaled ^Food allergy - oral ^Wheal and flare - subcutaneous ^Systemic - IV Q94=Describe the mechanisms by which antibodies directed against cell-associated or tissue antigens induce injury. A94=1) Binding of antibody to host antigen altered by a drug. ^2) Binding of antibody to soluble drug, followed by Fc binding to RBC. ^3) Binding of antibody to drug on RBC surface. ^4) Antibody dependent cell mediated cytotoxicity (ADCC) ^5) Antibody against foreign RBCs in a transfusion. Q95=Describe the mechanisms of complement-mediated cell lysis, opsonin dependent phagocytosis and antibody-dependent cell cytotoxicity (ADCC). A95=complement-mediated cell lysis = Kupfer cell and splenic macrophage phagocytosis ^opsonin dependent phagocytosis = complement-mediated cell lysis and phagocytosis ^antibody-dependent cell cytotoxicity (ADCC) = NK cell killing without phagocytosis Q96=Describe the immunopathologic mechanisms that are responsible for the renal and lung injury observed in Goodpasture s syndrome. A96=1) Loss of tolerance for basement membrane in kidney and lung (non-collagenous epitope) ^2) IgG and complement are involved ^3) Membrane attack complex formation affects / damages neighboring cells ^4) Damage to capillary walls in lung and glomerulus Q97=Describe the possible effects that antibodies directed against receptors on cell membranes may have on the physiologic responses of the cell. A97=1) Hyperthyroidism / Graves disease - IgG stimulates TSH receptor and leads to excess TH ^2) Myesthenia Gravis - IgG to AchR blocks transmission and leads to muscle weakness Q98=Describe the immunopathologic mechanisms by which the formation and/or deposition of circulating immune complexes in tissues will elicit inflammatory responses and tissue injury (i.e. Arthus reaction, one-shot serum sickness model). A98=1) IgG binds to large amounts of antigen and the antigen-antibody complexes deposit on vascular wall. ^2) Deposition triggers complement activation. ^3) Complement activation triggers chemotactic (C3a and C5a) influx of neutrophils. ^4) Neutrophils consume immune complexes. ^5) Neutrophil response leads to tissue damage (fibroid necrosis) ^- ^vessel wall necrosis - coagulating protein leakage - coagulation activation - fibrin deposition Q99=Describe the immunofluorescence and electron microscopic findings observed in immune complex-mediated tissue injury (Type III reactions) with those observed in Goodpastures syndrome (Type II reactions). A99=Type II - linear immunofluorescence because of antibodies against complement or IgG ^Type III - granular immunofluorescence because of antibodies against complement Q100=Describe the primary mechanisms involved in delayed type hypersensitivity reactions and T-cell mediated cytotoxicity. A100=1) Contact hypersensitivity - skin contacting something (e.g. poison ivy) ^2) Delayed-type hypersensitivity - infiltration of leukocytes (e.g. TB test) ^3) Granulomatous hypersensitivity - antigen persistence (e.g. mycobacterium Tuberculosis) ^4) T-cell mediated cytotoxicity ^- ^1) Contact hypersensitivity ^Primary - hapten + Langerhans => Langerhans to lymph node => T cell expansion ^Secondary - Langerhans stimulate memory T cells (Th1) => cytokine production => keratinocyte dissolution => acantholysis ^- ^2) Delayed-type hypersensitivity ^Previous exposure leads to CD4 memory cells ^(macrophages activate memory cells and stimulate them to produce cytokines) ^- ^3) Granulomatous hypersensitivity ^Antigen persistence => monocyte activation ^a) epitheloid cells = secrete cytokines ^b) activated macrophages = major secretor of cytokines and AAC derivatives ^b) multinucleated giant cell ^- ^4) T-cell mediated cytotoxicity ^CD8 lymphocytes and MHC I and IL-2 Q101=Describe four examples of disease-specific diagnostic autoantibodies and the clinical settings in which they occur. A101=1) Antiglomerular basement membrane (anti-GBM) ^* pulmonary-renal syndrome ^* Goodpastures syndrome ^* antibody binds to basement membrane ^- ^2) Antinuclear antibody (ANA) ^* antibodies against nuclear components (e.g. histones, DNA, etc.) ^- ^3) Antibodies to extractable nuclear antigens (ENA) ^* Ro, La, and Smith (Sm) antigens ^- ^4) Antineutrophil cytoplasmic antibodies (ANCA) ^* Wegeners granulomatosis (systemic or limited to lung or kidney) ^* microscopic polyarteritis ^* associated with pulmonary-renal syndromes Q102=Describe the basic principles of indirect immunofluorescence, enzyme immunoassay, Ouchterlony, and counter immunoelectrophoresis assay methods. A102=Indirect immunofluorescence = detection antibody different than primary antibody ^Enzyme immunoassay = bind antibody or antigen to plate and detect with enzyme activity (e.g. AP or HRP) ^Ouchterlony = double-diffusion to identify antigen-antibody interactions (concentration dependent) ^Counter immunoelectrophoresis assay = similar to Ouchterlony, but driven with electrophoresis Q103=Understand the basis of histocompatibility and allotypic variation. A103=MHC groove variation defines us each as individual. Q104=Describe the role of tissue matching in clinical transplantation. A104=Looking for similar MHC molecules reduces the likelihood of an immune response against the non-self MHC molecules. Q105=Identify the immunologic basis for each the different types of organ rejection. A105=1) Hyperacute rejection ^* previously sensitized ^* antibodies specific to graft ^* seen within minutes ^* involves complement and is exclusively antibody-mediated ^- ^2) Accelerated rejection ^* previously sensitized ^* involves T cells and antibodies ^* seen within 2-5 days ^- ^3) Acute rejection ^* involves T cells and antibodies ^* occurs with primary exposure ^*seen within 7-21 days ^- ^4) Chronic rejection ^* low-level recognition ^* involves T cells ^* occurs when there is only a small HLA difference ^* seen within months Q106=Describe the techniques for identifying allotypes of HLA. A106=1) Sequence fragments or the entire locus ^2) Use hybridization to detect discrepancies Q107=Describe the immunologic basis of autoimmune diseases and tolerance. A107=Two steps, in a specific order, are thought to be necessary for autoimmune disease: ^1) Initial inflammatory reaction - infection, trauma, AIDS, pregnancy, and inflammatory cytokine therapy ^2) Specific immune response ^- ^Tolerance is associated with a TCR binding to its appropriate MHC:peptide complex, but there is a lack of co-stimulatory molecules on the target cell (e.g. binding to a non-APC). Q108=Describe the mechanism of tissue damage in autoimmune diseases. A108=The primary mechanism is based on cytotoxic T cell induced apoptosis. Q109=Describe why immunity fails to prevent the growth of neoplasms. A109=Very few antigens on tumor cells are non-self. ^Some tumor cells secrete non-self antigens, which leads to an immune response away from the tumor. Q110=Describe the techniques for augmenting immune response to tumors. A110=induce MHC II expression ^immunize with specific tumor antigens ^grow tumor cells and leukocytes together to sensitize the leukocytes Q111=Describe the immunologic basis of inherited immune deficiencies. A111=1) cellular immune disorders ^* there is a problem with cytosolic pathogens (e.g. viruses or mycobacterium) ^* CD8 T cell abnormality ^- ^2) extracellular immune disorders ^* there is a problem with extracellular pathogens (e.g. bacteria or toxins) ^* CD4 T cell abnormality Q112=Describe the immunologic disorders manifest by HIV infection. A112=Affected people are unable to clear viruses, protozoa, and mycobacterium very well. ^Affected people will show systemic spread of typically localized infections (e.g. Herpes). Q113=Describe the clinical manifestations of four common immune deficiency diseases. A113=1) Severe combined immunodeficiency (SCID) ^* can be X-linked ^* stem cell or stem cell development disorders ^* receptor chain or DNA repair defects ^* DNA damage hinders lymphocytes, because they divide at a high rate ^- ^2) DiGeorge syndrome ^* affects cellular immunity ^* thymic aplasia, therefore a lack of T cell development ^* without T cell help, there is also a deficiency with antibody responses ^* with a lack of the parathyroid gland, patients often have hypercalcemia ^- ^3) Immunoglobulin deficiency disorders ^* specific for different steps in immunoglobulin development ^- ^4) Phagocytic and complement and NK cell deficiencies all present differently Q114=Describe the techniques for immune reconstitution in immune deficiency diseases. A114=Treat with immunoglobulins, either IM or IV, and treat with antibiotics. Q115=Describe the immunologic basis of allergic and hypersensitivity reactions. A115=1) Immediate hypersensitivity / allergic reaction ^2) Antibody-mediated (ADCC) or complement activation ^3) Immune complex disease (e.g. Arthus) ^4) Delayed type hypersensitivity Q116=Identify the cells and mediators involved in allergic reactions. A116=IgE and Mast cells and eosinophils Q117=Define asthma. A117=Chronic inflammatory disorders of airways, involving mast cells and eosinophils. Q118=Describe the pathophysiologic changes associated with asthma A118=Destruction of bronchial epithelium ^Thickening and fibrosis of basement and subbasement membrane ^- - - fibrosis is preventable and at least partially reversible ^Inflammatory cell infiltration ^Mucus plugging ^Interstitial edema ^Glandular hypertrophy and goblet cell hyperplasia ^Vasodilation Q119=Describe precipitating factors associated with asthma. A119=Allergies, aspirin, and beta-blockers ^- ^Aspirin sensitivity can be due to a shunt toward lipoxygenase, which leads to analphylaxis, respiratory arrest, asthma, nasal polyps, and chronic sinusitis. Q120=Describe the features used to determine the severity of an individuals asthma. A120=SYMPTOMS ^AM vs. PM ^Activity level ^Number of exacerbations ^FEV1 / EPFR (forced expiratory volume) ^PEFR variability (peak expiratory flow rate) Q121=Describe the medical management of asthma. A121=CONTROLLERS (long term) ^* inhaled corticosteroids (e.g. cromolyn sodium) - blocks all inflammatory response ^[blocking inflammatory response inhibits fibrotic reaction] ^* leukotriene modifiers ^* sustained release of theophyline - stabilizes the airway (old, not used much) ^* block eosinophils, mast cells, and cytokines ^- ^RELIEVERS (short term) ^* anti-cholinergics ^* systemic corticosteroids ^- ^HISTORICAL ^* used to treat with beta-agonists and steroids ^* now treat with controllers and relievers Q122=What is the equation for calculating variability? A122= Number of amino acids at a given position ^Variability = ----------------------------------------------------------------- ^ Frequency of the most frequent residue Q123=How many subclasses of the various immunoglobulin polypeptides are there? A123=No subclasses exist for the mu, epsilon, delta heavy chain polypeptides and the kappa light chain polypeptide. ^- ^Gamma = 4 subclasses ^Alpha = 2 subclasses ^Lambda = 10 subclasses Q124=Which immunoglobulins are secreted as multimers, how many monomers are found in each multimer, and what is the name of the extra polypeptide associated with immunoglobulin monomers? A124=Secreted IgM is a homopentamer. ^Secreted IgA is a homodimer. ^- ^The multimers each have one J chain polypeptide. Q125=What is the name of the polypeptide which links immunoglobulin monomers? A125=The J chain polypeptide. Q126=Which immunoglobulins have a proline-rich hinge? A126=IgG ^IgA ^IgD ^- ^Eek G.A.D, - they have a hinge! Q127=How many C region domains are found in each of the immunoglobulin heavy chains? A127=IgG = 3 ^IgA = 3 ^IgM = 4 ^IgD = 3 ^IgE = 4 Q128=What is an opsonin? A128=An opsonin is an antibody which enhances phagocytosis by macrophages and neutrophils. Q129=What do the following terms mean: isotype, allotype, and idiotype? A129=Isotype - is an antigenic determinant on an immunoglobulin that is expressed by all members of a species (e.g. gamma1, lamda1, alpha1) ^- ^Allotype - is an antigenic determinant on an immunoglobulin expressed by some, but not all, members of a species. (e.g. subtle differences in regions found in everyone that add a slight bit of diversity) ^- ^Idiotype - is an antigenic determinant expressed on a single immunoglobulin and is often combining-site specific. Q130=What are the possible products of IgG cleavage by papain and pepsin? A130=Papain = 2 x Fab + Fc ^each Fab is monovalent ^- ^Pepsin = F(ab)2 + pFc (pFc = pieces of Fc) ^each Fab is divalent Q131=Which cells posses Fc receptors and what are these receptors for? A131=Fc receptors are found on macrophages, neutrophils, dendritic cells, eosinophils, NK cells, and mast cells. ^- ^Fc receptors allow cells to bind to the Fc segment of antibodies. Q132=Compare/contrast affinity and avidity. A132=Affinity is the dissociation constant for the interaction of a single epitope with an Fab fragment. ^- ^Avidity is the experimentally determined value of the strength of the interaction of an antigen with a multivalent antibody. Q133=What are six proteins involved with down-regulating complement responses and what do they do? A133=Serum carboxypeptidase N (SCPN) = cleave the carboxy-terminus of C3a and C5a ^Factor I = inactivates convertase ^C1 esterase inhibitor (C1INA) = inhibits the C4/C2 binding ^Decay accelerating factor (DAF) = inhibits convertase ^Membrane co-factor protein (MCP) = inactivates convertase ^Protectin (CD59) = destabilizes the membrane attack complex Q134=What are some differences between B1 and B2 B cells? A134=B1 ^only represent 5 percent of B cells ^have CD5 ^responds better to carbohydrate antigen better than protein antigen ^B cell lymphomas are typically CD5 positive ^- ^B2 ^represent 95 percent of B cells ^don't have CD5 ^responds better to protein antigen better than carbohydrate antigen Q135=What are the peptide sizes bound by each MHC molecule? A135=MHC I can bind peptides with 8-10 amino acids. ^MHC II can bind peptides with 13-30 amino acids. Q136=Which cells express MHC I and which express MHC II? A136=All nucleated cells express MHC I. ^Professional APCs, B cells, and thymic epithelial cells express MHC II. Q137=What is the function of HLA-DO? A137=Negative regulator of HLA-DM, which loads peptides on the MHC class II molecule. Q138=What are the sources of peptides for MHC I and MHC II? A138=MHC I = proteosome ^(therefore must be transported to ER for loading) ^- ^MHC II = endosome/lysozome ^(therefore no transporting is required for loading) Q139=What is alloreactivity? A139=T cell stimulation by TCR recognition of a non-self MHC. Q140=Which cells are responsible for the positive and negative selection of T cells? A140=Positive selection ^Cortical epithelial cells ^ [recall thymic epithelial cells express MHC II and are first to see fluid entering the thymus] ^- ^Negative selection ^Dendritic cells, medullary epithelial cells, macrophages ^(at corticomedullary border) Q141=Which molecules secreted by T helper cells inhibit the development of the alternate pathway? A141=Th1 T cells secrete IFN-gamma, which inhibits Th2 formation. ^Th2 T cells secrete IL-10, which inhibits Th1 formation. Q142=Which cells have the CD40 receptor on their membrane and which have the CD40 ligand? A142=CD40 receptor = B cells ^CD40 ligand (CD40L) = Th2 T helper cells Q143=How can cytotoxic T cells kill target cells? A143=The Fas ligand is expressed on the cytotoxic T cells (CTL). ^The Fas receptor is expressed on target cells. ^Binding of the TCR to the MHC:peptide complex and the FasL to Fas lead to apoptosis. ^- ^CTLs can also kill with lytic granules containing active perforin (pore forming protein) and granzymes (serine proteases). Q144=What enzymes are responsible for rearranging immunoglobulin and T cell receptors? A144=RAG1 and RAG2 ^RAG = recombination activated genes Q145=What restriction exists with RAG recombination in terms of flanking DNA? A145=RAG can only join a segment of DNA with one turn (11 bp) to a segment with two turns (23 bp). Q146=What are two potential intracellular signaling pathways utilized by binding of C5a, C3b, and Fc to phagocytic cells? A146=All three receptors can utilize a G-protein regulated pathway which can then feed into phosphoinositide metabolism or tyrosine kinase activation. Q147=What are the four effects of C5a, C3b, and Fc binding to phagocytic cells? A147=Binding of these molecules stimulates: ^1. Conversion from a migrating cell to an invading cell ^2. Phagocytic response ^3. Degranulation ^4. NADPH oxidase activation Q148=What two molecular units can be used to stimulate opsonization? A148=Antibodies ^Complement components Q149=What are some molecules released upon degranulation? A149=Serine proteases (e.g. elastase) ^Metalloproteinases (e.g. collagenase) ^Acid hydrolases ^Defensins Q150=What are defensins and when are they used? A150=Defensins are small, cationic molecules secreted upon degranulation and, upon binding to bacteria, can cause injury and lysis of the bacteria. Q151=What is involved in activation of NADPH oxidase and what cells carry it? A151=NADPH oxidase is a multisubunit protein that is dissociated until activation and is found in neutrophils, macrophages, and eosinophils. Q152=What three enzymes are involved in protecting the body from reactive oxygen species? A152=Superoxide dismutase ^Catalase ^Glutathione peroxidase Q153=What three molecules are non-specific anti-oxidants? A153=Vitamin E ^Vitamin C ^Beta-carotene Q154=What molecules activate metalloproteases? A154=Serine proteases (e.g. elastase) activate metalloproteases (e.g. collagenase). Q155=What three enzymes inactivate proteases? A155=alpha1-antiprotease (aka alpha1-antitrypsin) inactivates serine proteases (e.g. elastase) ^alpha2-macroglobulin inactivates metalloproteases (e.g. collagenase) ^TIMPs inactivate metalloproteases Q156=What do RAST and RIST test for? A156=RAST = radioallergosorbent test ^tests for specific IgE ^- ^RIST = radioimmunosorbent test ^tests for total IgE Q157=What are the direct and indirect Coombs tests? A157=Direct ^Add only secondary antibody to fetal RBCs and then ask if there are maternal antibodies sticking to the RBCs. ^- ^Indirect ^Incubate maternal serum with Rh+ RBCs Q158=What is important about the outcome of cycosporin A therapy? A158=Cyclosporin A affects only the development of new immunity and doesn't affect previously developed immunity. ^Cyclosporin A is the only agent that is specific for the activation steps in cytotoxic T lymphocytes. Q159=Persistent infections of which bacteria are associated with B cell/immunoglobulin deficiencies? A159=Pneumococci ^Haemophilis influenza ^Streptococcus ^- ^In general, the highly encapsulated or pyogenic bacteria are most difficult to kill because of problems with opsonization. Q160=What are two disorders associated with with B cell/immunoglobulin deficiencies? A160=X-linked, or Bruton's, Agammaglobulinemia ^Results from abnormal B cell development due to the loss of BTK, a specific enzyme. ^Pre-B cell to B cell transition is blocked. ^- ^Common variable hypogammaglobulinemia ^Have B cells ^Unknown etiology ^- ^Both are of interest, because they present with the same clinical syndrome. ^Treat both with immunoglobulin replacement. Q161=What is the abnormality seen in individuals with X-linked Hyper IgM? A161=These individuals are unable to class-switch, because of a defect in T cell GP39, which is a ligand for CD40. ^- ^Patients have high levels of IgM. Q162=Autoimmunity does/does not have a significant genetic component? A162=Does Q163=What is one of the best indications of a T cell deficiency? A163=A poor delayed-type hypersensitivity by skin test. Q164=What disorders give SCID, or T cell deficiency, phenotype? A164=Wiskott-Aldrich syndrome (WAS; X-linked) - defective T and B cells, defective platelets ^Adenosine deaminase (ADA) deficiency - defective purine degradation ^Purine nucleotide phosphorylase (PNP) deficiency - defective purine degradation ^Bare lymphocyte syndrome - lack of MHC II molecules and therefore a lack of CD4 T cells Q165=What disorders yield deficiencies in phagocytosis? A165=Chronic granulomatous disease - defective NADPH oxidase ^Leukocyte adhesion deficiency - defective integrin subunit (CD18)