title: Ultraviolet B suppresses immunity by inhibiting effector and memory T cells.
abstract: Contact hypersensitivity is a T-cell-mediated response to a hapten. Exposing C57BL/6 mice to UV B radiation systemically suppresses both primary and secondary contact hypersensitivity responses. The effects of UVB on in vivo T-cell responses during UVB-induced immunosuppression are unknown. We show here that UVB exposure, before contact sensitization, inhibits the expansion of effector CD4+ and CD8+ T cells in skin-draining lymph nodes and reduces the number of CD4+ and IFN-gamma+ CD8+ T cells infiltrating challenged ear skin. In the absence of UVB, at 10 weeks after initial hapten exposure, the ear skin of sensitized mice was infiltrated by dermal effector memory CD8+ T cells at the site of challenge. However, if mice were previously exposed to UVB, this cell population was absent, suggesting an impaired development of peripheral memory T cells. This finding occurred in the absence of UVB-induced regulatory CD4+ T cells and did not involve prostaglandin E2, suggesting that the importance of these two factors in mediating or initiating UVB-induced immunosuppression is dependent on UVB dose. Together these data indicate that in vivo T-cell responses are prone to immunoregulation by UVB, including a novel effect on both the activated T-cell pool size and the development of memory T cells in peripheral compartments.
authors.affiliation: Department of Medicine, Melanoma and Skin Cancer Research Institute, Sydney Cancer Centre, The University of Sydney, NSW 2006, Australia.
authors.forename: Sabita
authors.initials: S
authors.lastname: Rana
authors.forename: Scott Napier
authors.initials: SN
authors.lastname: Byrne
authors.forename: Linda Joanne
authors.initials: LJ
authors.lastname: MacDonald
authors.forename: Carling Yan-Yan
authors.initials: CY
authors.lastname: Chan
authors.forename: Gary Mark
authors.initials: GM
authors.lastname: Halliday
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000528:radiation effects*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000528:radiation effects*; D002465:Cell Movement / Q000528:radiation effects; D049109:Cell Proliferation; D003877:Dermatitis, Contact / Q000276:immunology; D004423:Ear / Q000473:pathology / Q000528:radiation effects; D005260:Female; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007109:Immunity / Q000528:radiation effects*; D007156:Immunologic Memory / Q000528:radiation effects*; D007371:Interferon-gamma / Q000096:biosynthesis; D007962:Leukocytes / Q000473:pathology / Q000528:radiation effects; D008198:Lymph Nodes / Q000276:immunology / Q000528:radiation effects; D008213:Lymphocyte Activation / Q000528:radiation effects; D051379:Mice; D008810:Mice, Inbred C57BL; D010641:Phenotype; D012867:Skin / Q000473:pathology / Q000528:radiation effects; D050378:T-Lymphocytes, Regulatory / Q000276:immunology / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D049452:Green Fluorescent Proteins; D007371:Interferon-gamma