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 Printable version |
MHC class II-KO mice are resistant to the immunosuppressive effects of UV light. |
European Journal of Dermatology. Volume 12, Number 1, 10-9, January - February 2002, Revues
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 Free Article
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Author(s) : Maya KRASTEVA, François AUBIN, Sandrine LAVENTURIER, Jeanne KEHREN, Olga ASSOSSOU, Jean KANITAKIS, Dominique KAISERLIAN, Jean-François NICOLAS |
Summary : Ultraviolet B light is responsible for the development of skin cancer through inhibition of cellular immune responses in the skin. Here, we addressed the question of the mechanisms involved in UVB-induced immune suppression. We used a model of antigen-specific skin inflammation, the contact hypersensitivity (CHS) reaction to DNFB, which is mediated by CD8+ effector T cells and down-regulated by CD4+ T cells. We show that UVB have opposite effects on CD4+ and CD8+ T cells. UVB irradiation reduced the number of activated CD8+ T cells in the lymphoid organs and impaired their functional activity. This resulted in deficient infiltration of IFN-gamma producing CD8+ T cells at challenged site and consequently in the inability to develop an antigen-specific CHS reaction. This effect is mediated by CD4+ suppressor cells, since in the absence of CD4+ T cells (MHC class II-KO mice and CD4+ T cell-depleted mice), UVB have no immunosuppressive effects. Indeed, UVB-irradiated CD4+ T cell-deficient mice have a normal frequency of IFN-gamma-producing hapten-specific CD8+ T cells in the lymphoid organs and develop a normal CHS reaction to DNFB. Thus, in the absence of CD4+ T cells, UVB do not alter the priming of MHC class I-restricted CD8+ effector T cells. Collectively, these data show that UVB-induced immune suppression is secondary to preferential activation of CD4+ suppressor T cells and not to deficient priming and expansion of the effector CD8+ T cell population. This may have important implications for the prevention of UV-induced skin cancers. |
Keywords : contact hypersensitivity, dendritic cells, haptens, T cells, immune suppression, low dose UVB, CD4+ T cells, CD8+ T cells. |
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