Immunology Exam 2

Activation Unit

The combination of complement components C1, C4b, and C2b that form the enzyme C3 convertase, whose substrate is C3

Recognition Unit

the complement component that consists of the C1qrs complex; this must bind to at least two Fc regions to initiate the classical complement cascade

Proinflammatory

type of signaling that promotes inflammation

A patient in septic shock caused by a gram-negative bacterial infection exhibits the following symptoms: high fever, very low blood pressure and disseminated intravascular coagulation. Which cytokine is the most likely contributor to these symptoms? a. IL-2 b. TNF c. IL-12 d. IL-7

.TNF

If a specimen for complement testing was left on a laboratory bench overnight and not properly frozen, which of the following would be true? a. a CH50 level would be falsely low b. an AH50 level would be falsely high c. a measure of C3a would be falsely low d. a C3 level by nephelometry would be changed

A CH50 level would be falsely low

Which of the following are diseases associated with complement deficiencies/improper control? a. age-related macular degeneration (AMD) b. paroxysmal nocturnal hemoglobinuria (PNH) c. atypical hemolytic uremic syndrome d. C3 glomerulopathy e. all of the above f. only C and D

All of the above

Which of the following precursors is a target cell for IL-3? a. myeloid precursors b. lymphoid precursors c. erythroid precursors d. all of the above

All of the above

Mannose-binding protein in the lectin pathway is most similar to which classical pathway component? a. C3 b. C1rs c. C1q d. C4

C1q

All of the following are true of the recognition unit except a. it consists of C1q, C1r and C1s b. the subunits require calcium for binding together c. binding occurs at the Fc region of antibody molecules d. C1q becomes an active esterase

C1q becomes an active esterase

Which of the following is not a cofactor of Factor I? a. Factor H b. C4-binding protein c. membrane cofactor protein (MCP, CD46) d. C3bBbC3b

C3bBbC3b

Which best characterizes MAC (membrane attack complex)? a. each pathway uses different factors to form it b. C5 through C9 aren't added in any particular order c. one MAC unit is sufficient to lyse any type of cell d. C9 polymerizes to form the transmembrane channel

C9 polymerizes to form the transmembrane channel

Which would be the best assay to measure a specific cytokine? a. blast formation b. t-cell proliferation c. measurement of leukocyte chemotaxis d. Elisa testing

D. ELISA testing

Selective destruction of the Th cells by the HIV virus contributes to immune suppression by which means? a. decrease in IL-1 b. decrease in IL-2 c. decrease in IL-8 d. decrease in IL-10

Decrease in IL-2

A decreased CH50 level and a normal AH50 level indicate which deficiency? a. decrease in components in the lectin pathway only b. decrease in components in the alternative pathway only c. decrease in components of both classical and alternative pathway d. decrease in components of the classical pathway only

Decrease in components of the classical pathway only

Which of the following would result from a lack of TNF? a. decreased ability to fight gram-negative bacterial infections b. increased expression of class II MHC molecules c. decreased survival of cancer cells d. increased risk of septic shock

Decreased ability to fight gram-negative bacterial infections

All of the following represent functions of the complement system except a. decreased clearance of antigen-antibody complexes b. lysis of foreign cells c. increase in vascular permeability d. migration of neutrophils to the tissues

Decreased clearance of antigen-antibody complexes

A lack of IL-4 may result in which of the following effects? a. inability to fight off viral infections b. increased risk of tumors c. lack of IgM d. decreased eosinophil count

Decreased eosinophil count

Factor H acts by competing with which of the following for the same binding site? a. Factor B b. Factor D c. C3b d. Factor I

Factor B

A lack of C1-INH has been associated with which of the following conditions? a. paroxysmal nocturnal hemoglobinuria b. hemolytic uremic syndrome c. hereditary angioedema d. increased bacterial infections

Hereditary Angioedema

IFN-α and IFN-β differ in which way from IFN-γ? a. IFN-α and IFN-β are called Immune IFNs, and IFN-γ is not b. IFN-α and IFN-β primarily activate macrophages, whereas IFN-γ halts viral activity c. IFN-α and IFN-β are made primarily by activated T cells, whereas IFN-γ is made by fibroblasts d. IFN-α and IFN-β inhibit viral replication, whereas IFN-γ stimulates antigen presentation by class II MHC molecules

IFN-α and IFN-β inhibit viral replication, whereas IFN-γ stimulates antigen presentation by class II MHC molecules

IL-10 acts as an antagonist to which cytokine? a. IL-4 b. TNF-α c. IFN-γ d. TGF-β

IFN-γ

Which cytokine acts to promote differentiation of Tcells to the Th1 subclass? a. IL-4 b. IFN-γ c. IL-12 d. IL-10

IL-12

In vitro methods to detect a cell-mediated response to M. tuberculosis measure production of which of the following? a. IgE antibody b. IL-1 c. IL-2 d. INF-γ

IL-2

Which of the following cytokines is also known as the T-cell growth factor? a. IfN-γ b. IL-12 c. IL-2 d. IL-10

IL-2

Why might a CSF be given to a cancer patient? a. stimulate activity of NK cells b. increase the production of certain types of leukocytes c. decrease the production of TNF d. increase the production of mast cells

Increase the production of certain types of leukocytes

Which best describes the role of an anaphylatoxin? a. coats cells to increase phagocytosis b. attracts WBCs to the area of antigen concentration c. increases production of interleukin-1 d. increases permeability of blood vessels

Increases permeability of blood vessels

Which of the following is not true of the amplification loop in complement activation? a. improper control can lead to disease b. it can amplify activation that is initiated by the classical pathway c. C3b is the product that is increased d. increasing amounts of C1qrs are produced

Increasing amounts of C1qrs are produced

Which of the following effects can be attributed to IL-1? a. mediation of the innate immune response b. differentiation of stem cells c. halted growth of virally infected cells d. stimulation of mast cells

Mediation of the innate immune response

Which of the following would be expected to be true for the testing of a patient who's on a complement C5 inhibitor? a. low CH50 b. low AH50 c. high sCb5b-9 d. all of the above e. only A and B

Only A and B

Which of the following is referred to as C3 convertase? a. C1qrs b. C4bC2a c. C3bBb d. all of the above e. only b and c

Only B and C

The CH50 test measures which of the following? a. patient serum required to lyse 50% of sensitized sheep RBCs b. functioning of both the classical and alternative pathways c. genetic deficiencies of any of the complement components d. functioning of the lectin pathway only

Patient serum required to lyse 50% of sensitized sheep RBCs

Which of the following describes the role of properdin in the alternative pathway? a. stabilization of C3 convertase b. conversion of B to Bb c. inhibition of C3 convertase formation d. binding and cleavage of Factor B

Stabilization of C3 convertase

What is the major function of Treg cells? a. suppression of the immune response by producing TNF b. suppression of the immune response by inducing IL-10 c. proliferation of the immune response by producing IL-2 d. proliferation of the immune response by inducing IL-4

Suppression of the immune response by inducing IL-10

T helper 1 cells (Th1)

T cells that are developed through the expression of IL-12 by dendritic cells, and which are primarily responsible for cell-mediated immunity

T helper 2 cells (Th2)

T cells which are developmentally regulated by IL-4 and whose main function is to drive antibody-mediated immunity

Th17 cells affect the innate immune response by inducing production of which cytokines? a. IFN-γ and IL-2 b. IL-4 and IL-10 c. IL-2 and IL-4 d. TNF-α and IL-6

TNF-α and IL-6

Complement Receptor Type 1 (CR1)

a cell bound regulator of complement activation; it assists in degrading C3b and C4b and mediates transport of C3b-coated immune complexes to the liver and spleen

Erythropoietin (EPO)

a colony-stimulating factor that increases RBC production in the bone marrow

Hemolytic Uremic Syndrome (HUS)

a condition characterized by hemolytic anemia, low platelet count, and acute renal failure caused by either a Shiga toxin related to an infection or complement dysregulation

S Protein

a control protein in the complement cascade that interferes with binding of the C5b67 complex to a cell membrane, thus preventing cell lysis

Factor H

a control protein in the complement system; it acts as a cofactor with factor I to break down C3b formed during complement activation

Granulocyte-Macrophage Colony-Stimulating Factor (GM-CSF)

a cytokine produced by T cells and other cell lines that stimulates increased production of granulocytic cells and macrophages

Granulocyte Colony-Stimulating Factor (G-CSF)

a cytokine produced by fibroblasts and epithelial cells that enhances the production of neutrophils

Transforming Growth Factor-Beta (TGF-β)

a cytokine that induces antiproliferative activity in a variety of cell types and downregulation of the inflammatory response

Macrophage Colony-Stimulating Factor (M-CSF)

a cytokine that induces growth of hematopoietic cell destined to become monocytes and macrophages

Paroxysmal Nocturnal Hemoglobinuria (PNH)

a disease characterized by complement-mediated hemolysis of erythrocytes resulting from a deficiency of decay-accelerating factor on the red blood cells (RBCs)

Hereditary Angioedema (HAE)

a disease characterized by swelling of the extremities, the skin, the gastrointestinal tract, and other mucosal surfaces as a result of a deficiency in the complement inhibitor C1NH

Colony-stimulating factor (CSF)

a family of cytokines in human serum that promote hematopoiesis and the differentiation of monocytes, granulocytes and erythrocytes

Decay-Accelerating Factor (DAF)

a glycoprotein found on peripheral red blood cells (RBCs), endothelial cells, fibroblasts, and epithelial cell surfaces that is capable of dissociating C3 convertases formed by both the classical and alternative pathways of complement

C1 Inhibitor (C1-INH)

a glycoprotein that acts to dissociate C1r and C1s from C1q, thus inhibiting the first active enzyme formed in the classical complement cascade

Interleukin

a group of cytokines produced by leukocytes and other cells that regulate adaptive immune responses and the inflammatory process

Chemokines

a large family of homologous cytokines that promote migration of WBCs through chemotaxis

Alternative Pathway

a means of activating complement proteins without an antigen-antibody combination; this pathway is triggered by constituents of microoraganisms

ELISpot

a modified ELISA technique that detects the frequency of cultured cells that secrete a particular cytokine

Lectin Pathway

a pathway for the activation of complement based on binding of mannose-binding protein to constituents on bacterial cell walls

Bystander Lysis

a phenomenon that occurs in complement activation when C3b becomes deposited on host cells, making them a target for destruction by phagocytic cells

Redundancy

a phenomenon that occurs when different cytokines have the same effect

Membrane Cofactor Protein (MCP)

a protein found on all epithelial and endothelial cells that helps to control complement-mediated lysis by acting as a cofactor for Factor I-mediated cleavage of C3b

C4-Binding Protein (C4BP)

a protein in the complement system that serves as a cofactor for factor 1 in the inactivation of C4b

Chemotaxin

a protein or other substance that acts as a chemical messenger to produce chemotaxis

Mannose-Binding Lectin (MBL)

a protein present in the blood that binds to mannose on bacterial cells and initiates the lectin pathway for complement activation

Properdin

a protein that stabilizes the alternative pathway C3 convertase

Atypical Hemolytic Uremic Syndrome (aHUS)

a rare genetic disorder associated with defects in complement regulation that cause microvascular thrombosis and affect the kidneys

Classical Pathway

a series of steps involved in the activation of complement that begins with antigen-antibody binding

Cascade

a series of steps that occur in a progressive manner, for example, the classical pathway of complement/the secretion of a cytokine by a cell that activates target cells to produce additional cytokines

Factor I

a serine protease that cleaves C3b and C4b formed during complement activation; a different cofactor is required for each of these reactions

Anaphylatoxin

a small peptide formed during complement activation that causes increased vascular permeability, contraction of smooth muscle and release of histamine from basophils and mast cells

T regulatory (Treg) cells

a subpopulation of T cells that play an important role in suppressing the immune response to self-antigens

T helper 17 cells (Th17)

a subset of T cells that play an important role in host defense against bacterial and fungal infections at mucosal surfaces; they secrete IL-17, which attracts neutrophils to the site of infection

Endogenous Pyrogen

a substance produced by the body that causes fever; IL-1 is an example

Which of the following is associated with an increase in IgE production? a. transfusion reaction b. activation of Th2 cells c. reaction to poison ivy d. hemolytic disease of the fetus and newborn

activation of Th2 cells

All of the following are associated with type I hypersensitivity except a. release of preformed mediators from mast cells b. activation of complement c. cell-bound antibody bridged by antigen d. an inherited tendency to respond to allergens

activation of complement

Which best describes the role of CR2 on cell membranes? a. binds C1qrs to inactivate it b. acts as co-receptor on B cells for antigen c. increases clearance of immune complexes d. binds particles opsonized with C3b

acts as co-receptor on B cells for antigen

Hemolytic Titration (CH50) Assay

an assay that measures complement-activating ability by determining the amount of patient serum required to lyse 50% of a standardized concentration of antibody-sensitized sheep erythrocytes

Which of the following is a general characteristic of hypersensitivity reaction? a. the immune responsiveness is depressed b. antibodies are involved in all reactions c. an exaggerated immune response to an antigen occurs d. the antigen triggering the reaction is a harmful one

an exaggerated immune response to an antigen occurs

The classical component pathway is activated primarily by a. most viruses b. antigen-antibody complexes c. fungal cell walls d. mannose in bacterial cell walls

antigen-antibody complexes

Which of the following would cause a positive DAT test? a. presence of IgG on RBCs b. presence of C3b or C3d on RBCs c. a transfusion reaction caused by preformed antibody d. any of the above

any of the above

Which of the following is associated with anaphylaxis? a. buildup of IgE on mast cells b. activation of complement c. increase in cytotoxic T cells d. large amount of circulating IgG

buildup of IgE on mast cells

Interferons (INFs)

cytokine produced by T cells and other cell lines that inhibit viral synthesis/act as immune regulators

Membrane Attack Complex (MAC)

the combination of complement components C5b, C6, C7, C8 and C9 that becomes inserted into the target-cell membrane, causing lysis

What is the immune phenomenon associated with the Arthus reaction? a. tissue destruction by cytotoxic T cells b. removal of antibody-coated RBCs c. deposition of immune complexes in blood vessels d. release of histamine from mast cells

deposition of immune complexes in blood vessels

What is the mechanism involved in type III hypersensitivity reactions? a. cellular antigens are involved b. deposition of immune complexes occurs in antibody excess c. only heterologous antigens are involved d. tissue damage results from complement-mediated lysis

deposition of immune complexes occurs in antibody excess

C3 Glomerulopathies (C3G)

diseases involving the glomeruli of the kidneys

Hypercytokinemia

dysregulation of cytokines, producing hyperstimulation of the immune response

Synergistic

effect of cytokines that complement and enhance each other

Autocrine

effect produced by a cell that stimulates the same cell

Antagonism

effect that occurs when the action of one cytokine counteracts the activity of another cytokine

Tumor Necrosis Factor (TNF)

family of cytokines that mediate the innate defense against gram-negative bacteria and effect adaptive immune responses

Which of the following represent an autocrine effect of IL-2? a. increased IL-2 receptor expression by the Th cell producing it b. macrophages signaled to the area of antigen stimulation c. proliferation of antigen-stimulated b cells d. increased synthesis of acute-phase proteins throughout the body

increased IL-2 receptor expression by the Th cell producing it

Endocrine

internal secretions of substances, such as hormones/cytokines, directly into the bloodstream that causes systemic effects

Which of the following best characterizes HUS? a. it is a common cause of renal failure in children b. it never has neurological manifestations c. it is associated with a high platelet count d. it is associated with antibody to C3 convertase

it is a common cause of renal failure in children

Pleiotropy

many different actions of a single cytokine; cytokine may affect the activities of more than one kind of cell and have more than one kind of effect on the same cell

Which of the following is characteristic of complement components? a. normally present in serum b. mainly synthesized by B cells c. present as active enzymes d. heat stable

normally present in serum

To determine a cold agglutinin titer a. patient serum should be separated from whole blood at 4°C and tested at 4°C b. patient serum should be separated from whole blood at 4°C and tested at 37°C c. patient serum should be separated from whole blood at 37°C and tested at 4°C d. patient serum should be separated from whole blood at 37°C and tested at 37°C

patient serum should be separated from whole blood at 4°C and tested at 4°C

Which condition would result in hemolytic disease of the fetus and newborn? a. buildup of IgE on mother's cells b. sensitization of cytotoxic T cells c. exposure to antigen found on both mother and baby RBCs d. prior exposure to foreign RBC antigen

prior exposure to foreign RBC antigen

Paracrine

secretions such as cytokines that affect only target cells in close proximity

Opsonins

serum proteins that attach to a foreign substance and enhance phagocytosis (from the Greek word meaning "to prepare for eating")

To determine if a patient is allergic to ryegrass, the best test to perform is the a. total IgE test b. skin prick test c. DAT d. complement fixation

skin prick test

Cytokines

small protein that acts as a chemical messenger to affect the function/activity of other cells, especially cells of the immune system

Immune Adherence

the ability of phagocytic cells to bind complement-coated particles