One week following an injection of aqueous penicillin, a patient develops joint pains, a
red, pruritic skin rash, fever and lymphadenopathy. Presuming that the diagnosis of serum
sickness is correct:
A. the antibody involved is probably IgD.
B. the antibody involved is probably IgA.
C. no antibody is involved, since this syndrome is secondary to a cell-mediated immune
reaction.
D. the serum concentration of complement would be decreased.
E. readministration of penicillin at a later date could be accomplished without hazard.
D. the serum concentration of complement would be decreased.
Type III hypersensitivity reactions involve immune complexes that can activate the complement system, leading to complement consumption and a decrease in complement levels. The antibodies involved in serum sickness are typically IgG or IgM, not IgD or IgA.