Human epidermal cells (ECs) were grown in vitro from normalhuman foreskin and the changes of Langerhans cells (LCs) within theoriginal explants and the epidermal outgrowth were observed in culturewith ATPase staining, HLA - Dr monoclonal antibody indirectimmuno-fluorescence and enzyme labelling avidin-biotin complex (ABC)staining. The capacity of ECs to stimulate the proliferation of allogeniclymhocytes was tested in the mixed skin-lymphocyte culture response(MSLR). The ATPase HLA-Dr positive LCs were gradually decreasedand significantly deformed within the original explants in culture. 70% ofLCs was decreased 3 days after culture. 90% of LCs was lost and the LCsremained in the original explants were only seen their outline 7 days afterculture. LCs approximatively disappeared within the original explants 14to 21 days after culture. The ATPase, HLA - Dr positive LCs have neverbeen found within the epidermal outgrowth. The ECs which were freshlyisolated from skin explants potently stimulated the proliferation ofallogenic lymphocytes in the MSLR. The ECs which were separated fromthe original explants after 3 days of culture were significantly declinedtheir ability to stimulate the proliferation of allogenic lymphocytes in theMSLR. The ECs separated from the original explants after 7 days ofculture were lost their ability to stimulate the proliferation of allogeniclymphocytes in the MSLR. The ECs separated from the epidermaloutgrowth failed to stimulate the proliferation of allogenic lymphocytes inthe MSLR. These results suggested that the ECs grown in our culturesystem were declined their immunogenety of skin allografts. Human epidermal cells (ECs) were grown in vitro from normal human foreskin and the changes of Langerhans cells (LCs) within the vegetative explants and the epidermal outgrowth were observed in culture with ATPase staining, HLA - Dr monoclonal antibody indirectimmuno-fluorescence and enzyme labeling of avidin-biotin The capacity of ECs to stimulate the proliferation of allogeniclymhocytes was tested in the mixed skin-lymphocyte culture response (MSLR). The ATP of HLA-Dr positive LCs was was decreased continuously and significantly deformed within the original explants in culture. 70 % of LCs was decreased 3 days after culture. 90% of LCs was lost and the LCsremained in the original explants were only seen their outline 7 days afterculture. LCs approximatively disappeared within the original explants 14to 21 days after culture. The ATPase, HLA-Dr positive LCs have never found in the epidermal outgrowth. The ECs which were freshlyisolated from skin explants potently stimul ated the proliferation ofallogenic lymphocytes in the MSLR. The ECs separated from the original explants after 3 days of culture were significantly declined their ability to stimulate the proliferation of allogenic lymphocytes in theMSLR. The ECs separated from the original explants after 7 days of culture were lost their ability to stimulate the proliferation of allogenic lymphocytes in the MSLR. The ECs separated from the epidermal outgrowth failed to stimulate the proliferation of allogenic lymphocytes inthe MSLR. These results suggest that the ECs grown in our culture system were declined their immunogenety of skin allografts.