Allergic and toxic contact dermatitis: inflammatory cell subtypes in epicutaneous test reactions

Histochemical and immunohistochemical techniques were used to identify T lymphocytes, mononuclear phagocytes and plasma cells in situ from allergic and toxic epicutaneous test reactions. Intracellular alpha-naphthyl acetate esterase (ANAE), endogenous peroxidase and immunoglobulin were used as markers for inflammatory cells. In allergic contact dermatitis 76 +/- 7% of all cells were ANAE-positive T lymphocytes, 13 +/- 6% mononuclear phagocytes and 12 +/- 6% ANAE-negative cells. In toxic skin lesions the corresponding values were 64 +/- 20%, 18 +/- 15% and 18 +/- 6%, respectively. There were no statistically significant differences between the allergic and toxic skin reactions. The basic reaction type in allergic and toxic contact dermatitis seems to be similar, with possibly some qualitative and quantitative differences.