Acid alpha-naphthyl acetate esterase staining of T lymphocytes in human skin

T lymphocytes were stained in order to disclose alpha-naphthyl acetate esterase activity (ANAE staining) by adopting the method described by Mueller et al. In ANAE-staining of frozen sections from human lymph nodes, more than 90% of the lymphocytes in paracortical areas (T cell areas) were ANAE-positive, but in cortical follicles (B cell areas) less than 5% of the cells were positive. Lymphocytic infiltrations in various dermatoses (lichen ruber planus, psoriasis, SLE, atropic dermatitis, erythema multiforme, poikiloderma atrophicans vasculare, and Sézary syndrome) were investigated. A high percentage of ANAE-positive lymphoid cells (greater than 80%) was found in most cases. One patient with chron. lymphatic leukaemia, however, had a smaller proportion of ANAE-positive lymphocytic cells in an erythema multiforme skin infiltrate. ANAE staining seems to be an easy method for the identification of T lymphocytes in skin sections. The results of this investigation support the hypothesis that T lymphocytes have an affinity to skin.