T lymphocytes bearing the γδ T-cell receptor: a study in normal human skin and pathological skin conditions

The aims of this study were to investigate the presence of gamma delta T cells in normal human skin, and the possible role of these cells in cutaneous reactions. Twenty-eight samples of normal skin from various sites, and 52 biopsies from inflammatory and neoplastic skin conditions were investigated by immunohistochemical techniques. In normal human skin gamma delta T cells were infrequently seen in the epidermis and dermis. In the inflammatory and neoplastic dermatoses, gamma delta T cells were occasionally present, accounting for 0-5% of CD3+ cells in most of the biopsies examined. In one case of pityriasis lichenoides chronica and one case of lichen planus gamma delta T cells were found to be increased, accounting for 15% of the CD3+ cells in each case. Dermal gamma delta T cells were markedly increased in three of six cases of Langerhans cell histiocytosis, with up to 30% of dermal CD3+ cells showing positive staining to an anti-T-cell receptor gamma delta monoclonal antibody. In two of these cases gamma delta T cells were seen in both the dermis and the epidermis. In two further cases dermal gamma delta T cells were not a prominent feature, but small clusters of epidermal gamma delta T cells were observed. T cells bearing the gamma delta T-cell receptor are thus not a major feature of normal human epidermis, unlike the murine system, where the great majority of epidermal lymphocytes express the gamma delta T-cell receptor.(ABSTRACT TRUNCATED AT 250 WORDS)