Analysis of the mechanism of unresponsiveness produced by haptens painted on skin exposed to low dose ultraviolet radiation.

Acute, low dose ultraviolet B radiation of murine body wall skin followed by local application of DNFB produces a state of antigen-specific unresponsiveness. This state is maintained at least in part by an Lyt-1+ T cell that effects unresponsiveness by impairing the induction phase of contact hypersensitivity. The absence of suppressor cells capable of acting at the effector stage of immunity suggests that tolerogenic signals derived from the skin establish suppressor networks that are incomplete and perhaps different from networks that are induced by systemic administration of tolerogens. It is proposed that ultraviolet radiation produces its effects by impairing the antigen-presenting potential of resident Langerhans cells in whose absence hapten-derivatized keratinocytes (or their products) are able to deliver a tolerogenic signal.