In vivo evaluation of cellular immunity in different phases of contact dermatitis.

Contact dermatitis is a delayed hypersensitivity reaction involving the skin as shock organ. In a delayed cutaneous hypersensitivity reaction to contact with an antigen, the afferent, central and efferent phases of the immune reaction remain untouched and the individual concerned has a nonspecific inflammatory response capacity. Hence, delayed cutaneous hypersensitivity tests and the dinitrochlorobenzene (DNCB) test are of great use in evaluating this type of reaction. This prompted us to evaluate the in vivo response of patients suffering from contact dermatitis, as studies on this topic have been focused on animal experimentation or in vitro techniques. We chose 30 patients with contact dermatitis and studied them at three different stages, namely, when the patients showed the typical clinical signs (acute phase), when the lesions had subsided (intercrisis phase) and when the signs had recurred (acute outbreak). We subjected them to delayed cutaneous hypersensitivity tests and the DNCB test. Both techniques revealed a decrease in the response in the intercrisis phase with respect to the other two phases and to a control group.