Expression of Ia antigen on epidermal keratinocytes after the grafting of normal skin to nude mice.

During the course of experimentation designed to evaluate the migration of host Langerhans cells (LC) into normal skin grafted onto nude mice, we observed that the epidermal cells of these grafts were induced to express la determinants solely of graft origin. The data presented herein indicate that the expression of la by normal epidermal cells correlates with the infiltration of host LC into the graft. This la expression is restricted to the keratinocytes within the epidermis of the grafted skin, is first observed 7 to 9 days post-grafting, and persists within the grafted skin for greater than 12 wk. The induction of la expression by keratinocytes appears to be the result of the environment that is provided by the nude mouse host and is independent of both passenger lymphocytes within the skin graft and allogeneic differences between graft and host. We strongly believe that these studies provide the basis for the development of an experimental animal model system for investigating the potential role that la expression by epidermal cells may play in enhancing the immune response to antigens encountered in the skin.