Immuno 1: Hypersensitivity and allergy

Question 1

During appropriate immune reactions, there should be no tissue damage

Answer 1

F. May be concomitant tissue damage as a side effect, but as long as pathogen is eliminated quickly will be minimal and repaired easily

Question 2

Approrpaite immune tolerance occurs to what

Answer 2

Appropriate immune tolerance occurs to self, and to foreign harmless proteins: Food, pollens, other plant proteins, animal proteins, commensal bacteria

Question 3

What does development of appropriate immune tolerance involve

Answer 3

Involves antigen recognition and generation of regulatory T cells and regulatory (blocking) antibody (IgG4) production Antigen recognition in context of “danger” signals leads to immune reactivity, absence of “danger” to tolerance

Question 4

Hypersemsitivity reactions invole immune responses against what

Answer 4

Harmless foreign antigens (allergy, contact hypersensitivity) Autoantigens (autoimmune diseases) Alloantigens (serum sickness, transfusion reactions, graft rejection)

Question 5

Outline the 4 types of hypersenstivity reactions

Answer 5

Type I : Immediate Hypersensitivity Type II : Antibody-dependent Cytotoxicity Type III : Immune Complex Mediated Type IV : Delayed Cell Mediated

Question 6

t/f diseases often fit into a distinct catgory of immune hypersensitivity

Answer 6

F… lots are a mixture

Question 7

Examples of Type 1 immediate hypersestivity

Answer 7

Anaphylaxis Asthma Rhinitis -Seasonal -Perennial Food Allergy

Question 8

What occurs in type 1 immediate hypersenstivity

Answer 8

1^o Antigen exposure: -Sensitisation not tolerance -IgE antibody production -IgE binds to Mast Cells & Basophils 2^o Antigen Exposure -More IgE Ab produced -Antigen cross-links IgE on Mast Cells/Basophils -Degranulation

Question 9

Outline the 2 categoties of type II antibody-dependent hypersenstivity

Answer 9

Organ-specific autoimmune diseases Autoimmune cytopenias (Ab mediated blood cell destruction)

Question 10

Give examplesof the type II organi-soecific autoimmune diseases, adnd the antibody

Answer 10

-Myasthenia gravis (Anti-acetylcholine R Ab) -Glomerulonephritis (Anti-glomerular basement membrane Ab) -Pemphigus vulgaris (Anti-epithelial cell cement protein Ab) -Pernicious anaemia (Intrinsic factor blocking Abs)

Question 11

Outline types of type II, autuimmune cytopenias

Answer 11

Haemolytic anaemia Thrombocytopenia Neutropenia

Question 12

T/f.. pernicious anaemia is an example of an autoimmune cytopenia

Answer 12

F…. it is an organ specific aurommune disease

Question 13

Give 2 examples of tests for speicifc autoanibodies

Answer 13

Immunofluorescence ELISA eg anti-CCP (Cyclic Citrullinated Peptide Abs for Rheumatoid Arthritis)

Question 14

Outline type III reactions

Answer 14

Formation of Antigen-Antibody complexes in blood Complex deposition in blood vessels/tissue Complement & cell activation Activation of other cascades eg clotting Tissue damage (vasculitis)

Question 15

Outline examples of tissue damage (vasculitis) as part of type III immune complex hypersenstivity

Answer 15

Systemic lupus erythematosus (SLE) Vasculitides (Poly Arteritis Nodosum, many different types)

Question 16

Outline why vasculitis occurs in type III hypersensitivty

Answer 16

Antibodies bound to antigen then deposit in vessel walls (or tissue) and activate complement (C3) and cellular activatin (monocyte/neutrophil)

Question 17

What are the most common sites of vasculitis in type III hypersensitivity

Answer 17

Skin Renal (glomerulonephritis) Joints Lung

Question 18

Give examples of type IV delayed hypersensitivty responses

Answer 18

Chronic graft rejection GVHD Coeliac disease Contact hypersensitivity Many autoimmune diseases. Asthma, rhinitis and eczema , but they are TH2 mediated unlike the others.

Question 19

Outline the three main varieties of type IV delayed hypersensitivity reaction

Answer 19

Th1 Cytotoxic Th2

Question 20

Outlne the mechanisms of type IV hypersensitivtiy

Answer 20

Transient/Persistent Ag T cell activation of macrophages, CTLs Much of tissue damage dependent upon TNF & CTLs