Immune attack on tissues: hypersensitivity

Question 1

Regulated response = ?

Exaggerated response = ?

Answer 1

Protection

Hypersensitivity

Question 2

List the four types of hypersensitivity

Answer 2

1,2,3,4

Question 3

What types are antibody regulated

Answer 3

Types 1,2,3. Type 4 is cell mediated

Question 4

Type 1 hypersensitivity - atopic allergy- mediated by IgE and mast cells

Answer 4

.IgE binds to FceR on mast cells and crosslinked by specific allergens triggering the release of inflammatory mediators - induce inflammation and smooth muscle contraction (early phase)
.Th2 cells produce IL-4 - stimulates IgE production by B cells and IL-5 that stimulates eosinophils (late phase = chronic damage)

Question 5

Sensitivity to specific allergens can be assessed by what test?

Answer 5

Skin prick test induces a flare reaction

Question 6

Type II hypersensitivity - allergy or autoimmune - mediated by IgG, IgA or IgM antibodies

Answer 6

Antibodies bind to cell surface membranes - activates complement and neutrophils to release digestive products and reactive oxygen species –> damage

Question 7

Type III hypersensitivity - immune complex disease - mediated by antibodies

Answer 7

Antibodies and antigens crosslink to form an immune complex (IC) that can become lodged in tissues - can activate complement/neutrophils –> damage

Question 8

Type IV hypersensitivity - cell mediated - delayed response as it takes time for memory cells to be created

Answer 8

.ThC created by interacting w APCs. Activated cells can secrete cytokines - can activate macrophages
. Chronic phases of infections