Immunology L1: Hypersensitivity

Question 1

Type I

Answer 1

• Anaphylaxis;
• allergy;
• some forms of asthma
• Involves mast cell degranulation (fig.)

Question 2

Type II Hypersensitivity

Answer 2

Inflammation: Abs deposited in fixed tissues (basement membrane, ECM) cause inflammation

– Glomerulonephritis
– Hyperacute rejection of organ grafts

Opsonization & Phagocytosis

• Transfusion reactions
• Erythroblastosis fetalis: Maternal IgG crosses placenta
• Autoimmune hemolytic anemia
• Some drug reactions

Effects on Cell Function

• Myasthenia gravis: Abs to AChR prevent neuromuscular transmission
• Graves disease: Abs to TSH receptor stimulate thyroid
• Immune-mediated dermatitis: Abs to intercellular junction proteins lead to non-adhesion and blistering

Question 3

Type III: Immune Complex-mediated

Answer 3

Prototypes: serum sickness (non-self antigens), systemic lupus erythematosus (self antigens, Fig.)

Question 4

Type IV Hypersensitivity (DTH)

Answer 4

Prototypes: Tuberculosis, contact dermatitis, cellular transplant rejection (non- self antigens)