IMPAIRED IMMUNOSUPPRESSIVE RESPONSE TO ULTRAVIOLET-RADIATION IN INTERLEUKIN-10-DEFICIENT MICE

Exposure to mid-range ultraviolet radiation (UVR) [280-320 mn, ultravi olet B (UVB) radiation] inhibits the acquisition of delayed-type hyper sensitivity in mice and contact hypersensitivity in rodents and humans , Intraperitoneal administration of interleukin 10 (IL-10) inhibits th e sensitization of mice to alloantigens for a delayed-type hypersensit ivity reaction and administration of neutralizing antibodies to IL-10 largely, but not totally, blocks the UVR-mediated suppression of the a bility to sensitize mice, This suggests that these inhibitory effects of UVB radiation may be mediated by release of IL-10. To test this hyp othesis directly, IL-10 gene-targeted (IL-10) mice lacking expression of IL-10 were examined for the ability of UVB radiation to suppress in duction of delayed-type hypersensitivity to alloantigens. IL-10T mice were completely resistant to UVB-induced immunosuppression in this sys tem, Interestingly, UVB radiation could suppress in IL-10T mice the in duction of contact hypersensitivity to a hapten applied to the skin at a site distant of irradiation, supporting the concept that regulation pathways of delayed-type hypersensitivity and contact hypersensitivit y responses by WR differ. These data provide additional understanding of the mechanisms of immunosuppression induced by UVR and suggest that IL-10 release subsequent to UVB radiation map play a role in the grow th of immunogenic UVB-induced cutaneous malignancies in the primary ho st.