Pustular irritant dermatitis due to croton oil. Evaluation of the role played by leukocytes and complement.

To elucidate the pathomechanisms of irritant pustular dermatitis and to evaluate the role of leukocytes in pustulation induced by croton oil, we compared the skin responses in leukopenic-and decomplemented guinea pigs with those in control saline-injected animals, to 1% croton oil application. Both decomplemented and control animals responded similarly to croton oil, showing erythema and pustulation at 24 h after topical application; microscopically numerous mononuclear and polymorphonuclear cells infiltrated the skin. Meanwhile, the clinical and histopathological response of leukopenic animals to croton oil was significantly depressed. Time-course study of inflammatory infiltrate in the dermis of controls revealed that mononuclear cells preceded the infiltration of polymorphonuclears. Although leukocytes constitute an important component in croton oil dermatitis, our results suggest that unclarified chemical mediators, other than complement-derived chemotactic factors, play a crucial role as a primary chemoattractant in the production of pustulation at the croton oil-applied site.