Hypersensitivity Rxs

Question 1

Type I HS Rx

Answer 1

*Anaphylactic and atopic—free antigen crosslinks *IgE–>release *histamine

First (type) and Fast (anaphylaxis)

Allergic and atopic disorders (eg, rhinitis, hay fever, eczema, hives, asthma)
ƒAnaphylaxis (eg, bee sting, some food/drug allergies)

ACID

• Anaphylactic and Atopic (type I)
• Cytotoxic (antibody mediated, type II)
• Immune complex (type III)
• Delayed (cell mediated, type IV)

Question 2

Type II HS Rx

Answer 2

Cytotoxic (antibody mediated)—IgM, IgG bind to fixed antigen on “enemy” cell–>cellular destruction

Type II is cy-2-toxic.

Antibody and complement lead to *MAC

Disease tends to be specific to tissue or site where antigen is found

*Acute hemolytic transfusion reactions
ƒ*Autoimmune hemolytic anemia
ƒ*Bullous pemphigoid
ƒ*Erythroblastosis fettles
ƒ*Goodpasture syndrome
ƒ*Graves disease
ƒ*Guillain-Barré syndrome
ƒ*Idiopathic thrombocytopenic purport
ƒ*Myasthenia graves
ƒ*Pemphigus vulgaris
ƒ*Pernicious anemia
ƒ*Rheumatic fever

ACID

• Anaphylactic and Atopic (type I)
• Cytotoxic (antibody mediated, type II)
• Immune complex (type III)
• Delayed (cell mediated, type IV)

Question 3

Type III HS Rx

Answer 3

Immune complex—*antigen-antibody (IgG) complexes activate *complement, which attracts neutrophils

neutrophils release lysosomal
enzymes

Can be associated with vasculitis and systemic
manifestations.

In type III reaction, imagine an immune complex as 3 things stuck together: antigen-antibody-complement.

*Arthus reaction
ƒ*SLE
ƒ*Polyarteritis nodosa
ƒ*Poststreptococcal glomerulonephritis
ƒ*Serum sickness

ACID

• Anaphylactic and Atopic (type I)
• Cytotoxic (antibody mediated, type II)
• Immune complex (type III)
• Delayed (cell mediated, type IV)

Question 4

Type IV HS Rx

Answer 4

Delayed (T-cell–mediated) type—sensitized *T cells encounter antigen and then release cytokines (leads to *macrophage activation).

4th and last—delayed

Cell mediated; therefore,
it is not transferable by serum.

4 T’s = T cells, Transplant rejections, TB skin tests, Touching (contact dermatitis)

Contact dermatitis (poison ivy, nickel allergy)
ƒGraft-versus-host disease
ƒ*Multiple sclerosis.