T-cell receptor gamma delta bearing cells in normal human skin

T-cell antigen receptors (TCR) are divided into common alpha beta and less common gamma delta types. In the murine skin, TCR gamma delta+ cells have been reported to form the great majority of epidermal T lymphocytes. We have examined the relative contribution of TCR alpha beta+ and TCR gamma delta+ cells to the T-cell population in normal human skin. Serial sections of freshly frozen skin specimens were acetone fixed, incubated with anti-CD3, beta F1 (anti-TCR alpha beta), anti-TCR gamma delta-1 and anti-TCR delta 1 (anti-TCR gamma delta) monoclonal antibodies (MoAb), and stained with a highly sensitive method. Over 90% of the T cells of normal human skin are localized around the postcapillary venules of the dermis, while less than 5% are present within the epidermis. In papillary dermis, TCR gamma delta+ cells formed on average 7% (anti-TCR gamma delta-1) or 9% (anti-TCR delta 1) of the total number of CD3+ cells, while TCR alpha beta+ cells constituted up to 80%. In epidermis, these percentages were 18% and 29% for TCR gamma delta+ cells, and up to 60% for TCR alpha beta+ cells. It is concluded that there is no preferential immigration or in situ expansion of TCR gamma delta+ T cells in normal human skin, because the relative percentages found for the TCR alpha beta+ and TCR gamma delta+ populations in skin are comparable to those found in lymphoid organs and peripheral blood. However, the percentage of TCR gamma delta+ cells in epidermis seemed on average higher than in papillary dermis. Therefore, there may still be a difference in migration patterns of TCR gamma delta+ v TCR alpha beta+ cells, but this does not result in their preferential localization in human epidermis. The hypothesis that TCR gamma delta+ T cells have a specialized function in immunosurveillance of epithelia may thus not be valid for human epidermis.