Lympho‐epidermal Interactions in Patients Receiving Human Langerhans cell Free Cultured Epidermal Allografts as a Skin Substitute

Abstract

AbstractHuman Langerhans cell free epithelia can be cultured in vitro, and then can be used as epidermal allografts (EAG) without evidence of rejection. We studied the cellular basis of this phenomenon with mixed epidermal cell lymphocyte reactions (MELR). The capacity of donor‐derived epidermal cells to stimulate allogeneic control or recipient cells was abolished when stimulatory cells were Langerhans cell‐free cultured keratinocytes and respondors were obtained prior to grafting. Donor‐type cultured keratinocytes were able to induce a low response by host‐derived cells in assays conducted 2, 4 and 6 weeks after grafting, but not thereafter. They were unable to stimulate allogeneic cells unrelated to the recipient. The ability of crude epidermal suspensions with 2–4% Langerhans cells to stimulate host‐derived cells did not increase with time after grafting. No secondary type MELR could be evidenced, suggesting that grafting of EAG did not induce an in vivo immunization to class I antigens expressed by cultured epidermal cells. Lastly, host‐derived Langerhans cells were not able to restore the allostimulatory ability of Langerhans cell free epidermal cells from EAG donors when tested against host‐derived cells. This suggests that host‐derived Langerhans cells which colonize the grafts during the first few weeks following grafting cannot act in the presentation of foreign keratinocyte‐bound antigens, which may account for the absence of rejection noted.