UVB irradiation modulates systemic immune responses by affecting cytokine production of antigen-presenting cells

The immunosuppressive effects of UVB irradiation have been well documented. The production of cytokines by keratinocytes is considered to play a major role in the induction of local as well as systemic immunosuppression. It i s thought that partly due to the interaction of locally produced cytokines with antigen-presenting cells (APC) systemic effects, like antigen-specific tolerance, can be induced. In this study we examined the effect of UVB irr adiation on cytokine profiles of peripheral APC as well as the functional c onsequences. Our results indicate that UVB irradiation impairs T(h)1-mediat ed immune responses in vivo by suppression of the systemic IL-12p70 product ion. Splenic APC from UVB-exposed mice showed an enhanced production of pro staglandin E-2, IL-1, IL-6 and tumor necrosis factor-alpha after in vitro s timulation. Also, spleen cells from UVB irradiated IL-4(-/-) mice showed in creased IL-6 levels. These APC were less efficient in inducing IFN-gamma pr oduction by CD4(+) T cells and suppressed IgM production by B cells. We con clude that the altered cytokine profile of peripheral APC can be responsibl e for the systemic effects of UVB irradiation on the T(h)1/T(h)2 balance as well as on a cell responses.