Autoimmunity 2

Question 1

Name the 5 main functional classes of cytokines.

Answer 1

1. mediate innate immunity 2. regulate lymphocytes 3. activate inflammatory cells 4. affect leukocyte movement 5. Stimulate hematopoiesis

Question 2

What is the action of IL-12?

Answer 2

initiates the TH1 pathway

Question 3

What is the action of IL-4?

Answer 3

initiates the TH2 pathway recruits eosinophils and promotes IgE

Question 4

What is th action of IL-17?

Answer 4

initates TH17 pathway and recuriting neutrophils

Question 5

What is the action of TGF-B?

Answer 5

down-regulates the immune response

Question 6

What is the action of IL-5?

Answer 6

activates eosinophils

Question 7

What important proteins are encoded on chromosome 6?

Answer 7

chromosome 6 encode MHC/HLA proteins (class I and II invovled in antigen presentation)

Question 8

Describe the location and structure of class I MHC.

Answer 8

present on all nucleated cells and platelets, consist of a polymorphic a-chain linked to B2-microglobulin (loci HLA-A,B and C) and function to display all proteins made in the cell

Question 9

How do class MHC I cells interact with other cells?

Answer 9

CD8+ cells are class MHC I restricted and NK cells kill cells with abnormal or low class I MHC

Question 10

Describe the location and structure of class II MHC.

Answer 10

present on APCs, coded by HLA D (DP, DQ and DR) polymorphic a and B chains bind antigens

Question 11

What type of cells do MHC II class interact with?

Answer 11

CD4+ helper T-cells ar class II MHC restricted

Question 12

Name 4 diseases that show a strong association with specifc HLA molecules

Answer 12

ankylosing spondylitis (HLA B27), rheumatoid arthritis (DR4), hereditary hemochromatosis (HLA-A), 21-hydroxylase deficiency (HLSBw47)

Question 13

List the 4 broad headings of autoimmune disorders.

Answer 13

hypersensitivity reactions, autoimmune diseases, immune deficiency, amyloidosis

Question 14

What 3 general catagories of substances can trigger a hypersensitivity repsonse?

Answer 14

exogenous antigens, homologous substances and autologous substances

Question 15

What is the cause and result of a type I hypersentivity?

Answer 15

cause: antigen binds and cross links bound IgE on mast cells; results in variable rxn between hives and anaphylaxis

Question 16

Describe the 2 phases of type I hypersensitivity.

Answer 16

phase 1 is the immediate release of histamine that cuases vasodilation, edema and SM contraction; phase 2 cytokine release occurs 2-24hrs with infiltrate of eos, polys, basos and CD4+ which often cause tissue damage

Question 17

Explain the steps in the activation and degranulation of mast cells.

Answer 17

mast cells express Fc receptors that can bind IgE, antigen binds two adjacent surface IgE antibodies, cross linking activates the cell and causes degranulation

Question 18

Contrast primary and secondary mediators released in a type I hypersensitivity rxn.

Answer 18

primary: histamine, proteases, chemotactic factors ; secondary: cytokines and products of membrane phopholipids

Question 19

Besides cross linked IgE, name 5 stimui hat can act as mast cell activators.

Answer 19

complement anaphylatoxins (C5a/C3a), macrophage derived cytokines (IL-8), drugs (codeine/morphine), bee venom, physical stimuli (heat, cold, sunlight)

Question 20

Describe the sensitization process that mast cells undergo during first antigen exposure.

Answer 20

APC present the antigen to CD4+ cell which causes cytokine release and TH differentiation of that T cell to TH2, these cells produce more cyotkines driving the type 1 rxn (IL-4 IgE, TH2 devo; IL-5 eos; IL-13 IgE)

Question 21

What are the most fatal parts of anaphylactic shock?

Answer 21

laryngeal edema, bronchoconstriction, drop in BP

Question 22

What mediates a type II hypersensitivity rxn?

Answer 22

antibodies

Question 23

Summarize the classes of antibodies using MADGE.

Answer 23

IgM (Macro), IgA (malt-mucousal), IgD (surface of na•ve B-cells), IgG (gestation) IgE (eosinophil- AAA)

Question 24

Name the 4 major mechanisms of type II hypersensitivity.

Answer 24

opsonization/phagocytosis, ADCC, complement/Fc mediated inflammation and antibody mediated cellular dysfunction

Question 25

What are the mediator and effector cell types in a type II hypersensitivty reaction?

Answer 25

mediator: plasma cell produces antibody, effector: complement proteins and phagocytic cells

Question 26

Describe the process of antibody-dependent cellular cytotoxicity.

Answer 26

effector cells (with Fc receptor) kill target cells with IgG on the surface (does not invovle phagocytosis ro complement)

Question 27

Give several examples of type II hypersensitivity reactions.

Answer 27

transfusion rxns. Erythroblastosis fetalis, autoimmune hemolytic anemia

Question 28

What is the basis of complement and Fc mediated inflammation (type II hypersensitivity)?

Answer 28

antibodies are deposited in the extracellular tissues/matrix and IgG of IgM activate the complement causing inflammation (ie. Good pasture Syndrome where basement membrane is the target)