Antibodies to the costimulatory molecule CD86 interfere with ultraviolet radiation-induced immune suppression

Although almost all of the energy contained within the ultraviolet (UV) wavelengths of solar radiation is absorbed within the epidermis and upper layers of the dermis, UV irradiation can suppress the immune response to antigens introduced at distant, non-irradiated body sites. The production of immune modulatory cytokines, such as interleukin-10 (IL-10), by UV-irradiated keratinocytes and its effect on T helper type 1 (Th1)/Th2-cell balance are thought to play a major role in the induction of systemic immune suppression. Because it is suggested that costimulatory molecules, such as CD80 and CD86, differentially stimulate Th1 and Th2 cells we wished to investigate the role of these costimulatory molecules in the activation of immune suppression. We injected UV-irradiated mice with monoclonal antibodies to CD80 and CD86 and asked what effect, if any, this would have on UV-induced immune suppression. Anti-CD86, but not anti-CD80 or control rat IgG, blocked UV-induced immune suppression. Moreover, monoclonal anti-CD86 blocked the induction of suppressor T cells normally found in the spleens of the UV-irradiated mice. Monoclonal anti-CD86 also reversed the UV-induced impairment of systemic antigen-presenting cell function. IL-10 was detectable in the serum of UV-irradiated mice as compared with normal controls, and injecting UV-irradiated mice with anti-CD86, but not anti-CD80 or control rat IgG, blocked the secretion of IL-10 into the serum. We propose that UV exposure favours costimulation by CD86, which enhances the production of serum IL-10, thus suppressing Th1-cell-mediated immune reactions.