Interaction of cultured keratinocytes and fibroblasts from human psoriatic and normal skin in immunodeficient mice.

Clarification of the pathogenesis of psoriasis requires separate studies of the epidermis, dermis, and inflammatory cells. We previously subcutaneously transplanted a mixture of cultured human keratinocytes and fibroblasts into mice to develop cysts with human skin structures. Using this method, we separately cultured psoriatic and normal keratinocytes and fibroblasts. Four mixtures were prepared: normal keratinocytes and normal fibroblasts (NK/NF); psoriatic keratinocytes and normal fibroblasts (PK/NF); normal keratinocytes and psoriatic fibroblasts (NK/PF); and psoriatic keratinocytes and psoriatic fibroblasts (PK/PF). Each mixture was transplanted into immunodeficient mice to observe formation of cysts and histological changes. The cysts varied in structure depending on the mixture, which suggests that psoriatic keratinocytes and fibroblasts had some abnormalities. Psoriatic fibroblasts may be partially responsible for thickening of the epidermis. Cell differentiation might have been accelerated in psoriatic keratinocytes after transplantation, resulting in the loss of epidermis structures.