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Immediate decrease in antigen‐presenting function and delayed enhancement of interleukin‐I production in human epidermal cells after in vivo UVB irradiation

Human skin was irradiated in vivo with a single UVB dose (100 mJ/cm2 or 200 mJ/cm2) to examine simultaneously the antigen‐presenting function and interleukin‐1 (IL‐1) production capacity of irradiated epidermal cells (EC). Suction blisters were produced on irradiated areas on days 0, 3 and 7 after UVB. Irradiated EC were harvested and co‐cultured with autologous T lymphocytes in the presence of antigens (PPD, HSV) or mitogen (ConA). Culture supernatants were tested for IL‐1 activity using the thymocyte comitogenity assay. We found that a single 200 mJ/cm2 dose of UVB caused an immediate suppression of the antigen‐presenting function of EC, but no alteration in their IL‐1 production capacity or surface marker expression (ATPase, CD1). PPD‐and HSV‐induced lymphocyte proliferation was decreased 70‐80% and ConA‐driven proliferation 30% when compared to non‐irradiated EC. However, this suppression was restored on days 3 and 7 after UVB irradiation, this being coexistent with an increased capacity of EC to produce IL‐1. It remains to be elucidated whether the immediate UVB‐induced photoimmunosuppression observed in the present study is due to inhibitory mediators or impaired membrane function of EC or both.