Conditioning of Langerhans cells induced by a primary CD8 T cell response to self-antigen in vivo.

Using a previously described model of autoimmune skin disease, we addressed the question of how CD8 T cell responsiveness to self-Ag is regulated during chronic inflammation. In this model, CD8 T cells expand and induce tissue pathology directed at an epidermal self-Ag. However, we show here that this primary CD8 T cell response prevented subsequent expansion of a second CD8 T cell population with the same specificity. This lack of T cell accumulation was not due to Ag elimination, nor was it due to competition between the two T cell populations. However, skin-specific dendritic cells that present Ag in this model--Langerhans cells--underwent significant phenotypic changes associated with a compromised ability to stimulate naive T cells. Our study suggests that conditioning of dendritic cells may play a role in maintaining unresponsiveness to self-Ag during chronic inflammation.