IgE-Mediated Reactions (Gell-Coombs Type I)
ÎIgE-mediated reactions may occur after administration of a wide variety of drugs, biologicals, and drug formulation agents, with the most common agents being antibiotics. (C)
Cytotoxic Reactions (Gell-Coombs Type II) ÎCytotoxic reactions are very serious and potentially life-threatening. (C)
ÎImmunohemolytic anemias have occurred after treatment with quinidine, α-methyldopa, and penicillin. (C)
ÎPositive direct and indirect Coombs test results in immunohemolytic anemia may reflect the presence of drug-specific IgG, complement, or an Rh determinant autoantibody. (C)
ÎImmune-induced thrombocytopenia may result from treatment with heparin, quinidine, propylthiouracil, gold salts, sulfonamides, vancomycin, and other drugs. (C) Platelet membrane damage is mediated mainly by drug-immune serum complexes, which are adsorbed onto platelet membranes. (C)
ÎImmune-mediated granulocytopenia is uncommon but may be induced by cytotoxic antibodies synthesized in response to a variety of drugs. (C)
Immune Complex Reactions (Gell-Coombs Type III)
ÎImmune complex (serum sickness) reactions were originally described with use of heterologous antisera, but they may also be caused by some small-molecular-weight drugs and monoclonal antibodies. (C)
ÎThe chief manifestations of fever, rash, urticaria, lymphadenopathy, and arthralgias typically appear 1 to 3 weeks after starting an offending agent. (C)
ÎThe prognosis for complete recovery from serum sickness is excellent. However, symptoms may last as long as several weeks. Treatment with systemic corticosteroids and histamine1
receptor antihistamines may be required. (C)
ÎDrug-induced immune complex disease may occur after exposure to heterologous proteins (eg, thymoglobulin) or simple drugs (eg, penicillin, procainamide, phenylpropanolamine). (C)
Cell-Mediated Reactions (Gell-Coombs Type IV)
ÎContact dermatitis produced by topical drugs (eg, bacitracin, neomycin, glucocorticosteroids, local anesthetics, and antihistamines) and/or excipients contained in topical formulations are due to cell- mediated reactions. (C)
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