Rejection, after a slightly prolonged survival time, of Langerhans cell-free allogeneic cultured epidermis used for wound coverage in humans.

Autologous cultured epidermis (CE) grown from small skin biopsies in vitro has been successfully applied for wound grafting in humans. Since it has been reported recently that allogeneic CE might be tolerated as permanent wound cover, we investigated the properties of CE and its use as autologous and allogeneic grafts. Except for some differences, such as the absence of Langerhans cells and the lack of a stratum corneum, CE resembled its natural analogue. Autologous CE applied for grafting of leg ulcers and various surgical skin defects adhered firmly and permanently to the wound bed within 2 weeks, became regularly stratified, and formed a stratum corneum. Langerhans cells gradually entered the grafts; the dermis contained no inflammatory infiltrate. Allogeneic CE unmatched for MHC and blood group antigens used to partially cover tangentially excised third-degree burns, donor sites of split-thickness skin, and a defect after tumor excision initially survived well like the autografts. However, they were completely rejected after 10-22 (mean, 14.5) days, which is 4-5 days later than reported for split-thickness skin allografts. Clinically, rejection presented as "melting" of the graft. (Immuno)histologically, we found a dense mononuclear dermal infiltrate consisting predominantly of activated T cells, vacuolization, and single-cell necrosis of keratinocytes, as well as HLA-DR expression on keratinocytes, and finally separation and lysis of the epidermis. Limiting dilution analysis in 2 out of 4 allograft recipients revealed a considerable increase of circulating donor-specific cytotoxic T cell precursors during graft rejection. We conclude that grafting of allogeneic CE does not lead to permanent but to slightly prolonged graft survival.