The spectrum of inflammatory cell response to dimethyl sulfoxide.

Dimethyl sulfoxide (DMSO), depending upon the concentration and mode of application to the skin, can induce either a non-immunological immediate contact urticaria or an irritant reaction. The dermal cellular infiltrate after open application of varying concentrations of DMSO has been studied in an experimental guinea pig model. The composition of the dermal cellular infiltrate showed a spectrum dependent on the concentration and number of applications of DMSO. The immediate reaction infiltrate 3 h after application of 100% DMSO consisted of 50% granulocytes, basophils being predominant. On the other hand, 12% DMSO applied 3 x daily for 3 days (cumulative insult) caused histologically a cellular reaction in which 80% of the infiltrate consisted of mononuclear cells. The present findings are compared to the microscopic findings in 3 other cutaneous reactions previously studied in this animal model, namely, the Type I immediate hypersensitivity reaction, the Type IV delayed hypersensitivity reaction, and the irritant reaction. Differing cellular infiltrate patterns are discernible at the same time points. The study illustrates the spectrum of inflammatory reactions seen in the skin and provides background information for future clinical studies, for instance, on the role of the basophil granulocyte in immediate contact reactions.