title: Systemic suppression of delayed-type hypersensitivity by supernatants from UV-irradiated keratinocytes. An essential role for keratinocyte-derived IL-10.
abstract: Exposing murine keratinocyte cultures to UV radiation causes the release of a suppressive cytokine that mimics the immunosuppressive effects of total-body UV exposure. Injecting supernatants from UV-irradiated keratinocyte cultures into mice inhibits their ability to generate a delayed-type hypersensitivity reaction against allogeneic histocompatibility Ag, and spleen cells from mice injected with supernatant do not respond to alloantigen in the in vitro MLR. A unique feature of the immunosuppression induced by either total-body UV-exposure or injecting the suppressive cytokine from UV-irradiated keratinocytes is the selectivity of suppression. Although cellular immune reactions such as delayed-type hypersensitivity are suppressed antibody production is unaffected. Because the selective nature to the UV-induced immunosuppression is similar to the biologic activity of IL-10, we examined the hypothesis that UV exposure of keratinocytes causes the release of IL-10. Keratinocyte monolayers were exposed to UV radiation and at specific times after exposure mRNA was isolated or the culture supernatant from the cells was collected. IL-10 mRNA expression was enhanced in UV-irradiated keratinocytes. The secretion of IL-10 by the irradiated keratinocytes was determined by Western blot analysis. A band reactive with anti-IL-10 mAb was found in supernatants from the UV-irradiated but not the mock-irradiated cells. IL-10 biologic activity was determined by the ability of the supernatants from the UV-irradiated keratinocytes to suppress IFN-gamma production by Ag-activated Th 1 cell clones. Anti-IL-10 mAb neutralized the ability of supernatants from UV-irradiated keratinocytes to suppress the induction of delayed-type hypersensitivity in vivo. Furthermore, injecting UV-irradiated mice with antibodies against IL-10 partially inhibited in vivo immunosuppression. These data indicate that activated keratinocytes are capable of secreting IL-10 and suggest that the release of IL-10 by UV-irradiated keratinocytes plays an essential role in the induction of systemic immunosuppression after total-body UV exposure.
authors.affiliation: Department of Immunology, University of Texas, M. D. Anderson Cancer Center, Houston 77030.
authors.forename: J M
authors.initials: JM
authors.lastname: Rivas
authors.forename: S E
authors.initials: SE
authors.lastname: Ullrich
mesh_terms: D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D002460:Cell Line; D005856:Germ-Free Life; D006968:Hypersensitivity, Delayed / Q000276:immunology*; D007165:Immunosuppression Therapy / Q000379:methods*; D016753:Interleukin-10 / Q000096:biosynthesis* / Q000276:immunology*; D015603:Keratinocytes / Q000276:immunology* / Q000528:radiation effects*; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000096:biosynthesis; D014466:Ultraviolet Rays; D015854:Up-Regulation
chemical_list: D012333:RNA, Messenger; D016753:Interleukin-10