Clinical Features of Serum Sickness

 

Mechanism: immune complex formation following exposure to antigen (Type III hypersensitivity reaction)

 

Antigen sources:

(1) serum (containing albumin or other antigenic proteins) from non-human mammals

(2) infectious agents

(3) drugs

 

Onset: usually 7 to 12 days after first exposure to antigenic source, may be up to 6 weeks

 

The onset may occur after the antigenic source has been discontinued (if the antigen has a long half-life).

 

Clinical findings:

(1) fever

(2) joint pain

(3) urticaria and/or skin rash

(4) malaise

(5) lymphadenopathy

(6) myalgias

(7) angioedema

(8) variable glomerulonephritis

(9) variable hypersensitivity vasculitis, especially with chronic exposure

(10) variable myocarditis

 

Laboratory findings:

(1) circulating immune complexes

(2) complement activation with decreased plasma levels

(3) immune complex deposits at sites of inflammatory response

 

Continued exposure can result in a chronic disorder.