HAPTEN-SPECIFIC TOLERANCE INDUCED BY ACUTE, LOW-DOSE ULTRAVIOLET-B RADIATION OF SKIN IS MEDIATED VIA INTERLEUKIN-10

Because interleukin (IL)-10 is an immunoregulatory cytokine that is pr oduced by keratinocytes exposed to UVB radiation (WR), we determined w hether IL-10 participates in either failed contact hypersensitivity (C H) induction or tolerance after acute, low-dose UVR, Murine recombinan t IL-10 (200 ng) was injected intradermally on shaved abdominal skin, To assess the effects of IL-10 on CH induction, dinitrofluorobenzene ( DNFB, 185 mu g) was painted on the skin within 30 min after IL-10 was injected, and the mice were assayed 5 d later by ear challenge with di lute DNFB, To assess tolerance, DNFB (185 mu g) was painted a second t ime on normal body-wall skin 14 d after DNFB was first painted on LL-1 0-injected skin; CH was then assayed on day 10, We found that mice tha t received DNFB on IL-10-injected skin developed CH comparable in inte nsity to that observed in PBS-injected controls. Thus, this dose of IL -10 did not prove to be deleterious to CH induction if hapten was pain ted on the injected site within 30 min. By contrast, mice that first e xperienced DNFB within 30 min, 1 d, or 3 d after IL-10 had been inject ed intracutaneously displayed hapten-specific tolerance, Moreover, int raperitoneally injected anti-IL-10 antibody prevented UVR- and cis-uro canic acid-dependent tolerance; anti-IL-10 antibody had no effect on T NF-alpha-induced tolerance and failed to restore CH induction after UV R exposures, These data indicate that IL-10 is an important mediator o f the tolerance induced when hapten is painted on the skin of animals exposed to acute, low-dose UVR.