Studies on Human Epidermal Langerhans Cells

Epidermal cell suspensions were produced containing 3–6% HLA‐DR‐positive Langerhans cells. By using mixtures of epidermal cells and allogeneic T lymphocytes from donors sensitized to purified protein derivative of tuberculin (PPD) and herpes simplex virus (HSV), we could show that a proliferative in vitro response to these antigens, similar in strength to that seen in autologous combinations of macrophages or epidermal cells and T cells, could be obtained provided the epidermal cells shared both HLA‐D/DR determinants with the T‐cell donor. No antigen‐specific response was obtained in fully HLA‐D/DR‐disparate combinations. These results, together with previously reported data using other antigen‐presenting cells, further emphasize that one minimal requirement for antigen‐specific activation of T cells is co‐recognition of products of the self HLA‐D region.