Mechanisms of drug-induced allergic contact dermatitis

Allergic contact dermatitis is induced by a wide variety of drugs that trigger specific immune responses following topical exposure. Identified chemical structures involved in such reactions include the mercuric and thiosalicylic acid groups of thimerosal, the diphenylketone group of the anti-inflammatory drug ketoprofen, the amide or ester structure of local anesthetics, and the side-chain and thiazolidine ring of beta-lactams. The T cell responses to such compounds involve CD4+ and CD8+ alphabeta+ T lymphocytes and also CD4 /CD8 gammadelta+ T cells. Although "T helper 2" cytokine production by drug-specific human T cells from patients with allergic contact dermatitis has been described, T helper 1-like and T cytotoxic 1-like responses clearly play key roles in this cutaneous reaction.