Hypersensitivity Reaction

Question 1

Type 1 Acute

Answer 1

• min to 1 hour

- mast cell degranulation w/ production histamine

Question 2

Type 1 Late

Answer 2

• 3-12 hrs
• lasts hours to days
• eosinophilic inflammatory inflitrate
• caused by cytokines

Question 3

Type 2 Cytotoxic

Answer 3

• IgG binds to FIXED tissue antigen or cell receptors (AUTOantibodies) causing cell destruction
  EX-
  Cell receptors–> platelets, RBC & WBC’s
  Fixed tissue antigen–> Goodpasture ( basement membrane kidney/lung) & Myasthenia gravis (ACh receptor on muscle cells)

Question 4

Type 3 Immune Complex

Answer 4

• Ab + Ag (self or foreign)= Immune complex (IC)–> activate complement–> small vessel inflammation & necrosis
• Seen 1-2 weeks after exposure once increase Ab production so there is only slight antigen excess leading to big IC that precipitate in small vessels & activate complement causing LEUKOCYTOCLASTIC vasculitis
  -Ex:
  Serum sickness & Arthur reaction

Question 5

Type 4A Cell mediated

Answer 5

• Previously sensitized T-cells
  -Peak 24-72hrs
  EX-
  
  • TB test & some types contact derm

Question 6

Type 4B

Answer 6

-Cytotoxic T cells directly destroy target T cells
EX-
- allograft rejection & chronic hepatitis

Question 7

How does immunotherapy work

Answer 7

• increase in T regulatory cell secretion of IL-10

- blocks antibodies of IgG isotype

Question 8

Serum Sickness Sx

Answer 8

• ## fever, skin rash (urticaria & angioedema), joint pain, GI complains (nausea/vomiting) , proteinuria

Question 9

Cutaneous mastocytosis

Answer 9

• urticaria pigmentosa

- Darier sign- wheal on gentle stroke of macule

Question 10

Systemic mastocytosis

Answer 10

• urticaria pigmentosa

- abdominal sympt

Question 11

Malignant mastocytosis

Answer 11

• NO skin changes

- hepatosplenomegaly & lymphadenopathy

Question 12

Asthma Predictive Index

Answer 12

• Major
  
  • Parent asthma OR eczema
• Minor-
  
  • allergic rhiniti OR wheezing apart from colds & eosinophilia