Immuno

Question 1

Hypersensitivity reactions

Answer 1

Type 1 (immediate): IgE; basophils and mast cells; ex. Anaphylaxis and allergies
Type 2 (cytotoxic): IgG and IgM auto Ab, complement activation; NK cells, eosinophils, neutrophils, macrophages; ex. Autoimmune hemolytic anemia, good pasture syndrome
Type 3 (immune complex): deposition of Ab-Ag complexes, complement activation; neutrophils; ex. Serum sickness, PSGN, lupus
Type 4(delayed type): none; T cells and macrophages; ex. Contact dermatitis and TB skin test

Question 2

Serum sickness

Answer 2

Type 3 hypersensitivity reaction to non human proteins characterized by vasculitis resulting from tissue deposition of immune complexes. Clinical findings include fever, pruritic skin rash, and low serum C3 and C4 complement levels.

Question 3

Type I hypersensitivity rxn

Answer 3

On initial exposure, an allergen promotes Ab class switching to IgE, subsequent exposure promotes cross linking of IgE on basophils and mast cells, resulting in degranulation and release of of multiple vasoconstrictive mediators including histamine.
 Wheel and flare lesions