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

Summary The aims of this study were to investigate the presence of γδ 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 γδ T cells were infrequently seen in the epidermis and dermis. In the inflammatory and neoplastic dermatoses, γδ 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 γδ T cells were found to be increased, accounting for 15% of the CD3 + cells in each case. Dermal γδ 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 γδ monoclonal antibody. In two of these cases γδ T cells were seen in both the dermis and the epidermis. In two further cases dermal γδ T cells were not a prominent feature, but small clusters of epidermal γδ T cells were observed. T cells bearing the γδ 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 γδ T‐cell receptor. The finding of numerous γδ T cells in Langerhans cell histiocytosis suggests a possible functional relationship between γδ T cells and Langerhans cells or possibly a pathogenic role of these cells in Langerhans cell histiocytosis.