Effects of whole-body UVB irradiation on cytokine production by peripheralblood mononuclear cells from stage I melanoma patients

Ultraviolet(UV) radiation causes significant impairment of immunological fu nction in human skin. The immunosuppressive effects of UV radiation are tho ught to be due to local release of cytokines by human keratinocytes, leadin g to impaired function of epidermal antigen-presenting cells (APC) and fail ure to induce cutaneous delayed-type hypersensitivity (DTH) reactions. Rece nt studies have shown that individuals susceptible to UV-induced suppressio n of DTH may be more prone to develop skin cancer including malignant melan oma (MM). Since the causal relationship between UV radiation and the induct ion of MM still seems obscure, we investigated the immunological reactions of peripheral blood mononuclear cells (PBMC) to whole-body irradiation with UVB in 15 stage I melanoma patients as compared to PBMC from normal volunt eers matched for age, gender and skin type. Whole-body irradiation was perf ormed with 0.8 minimal erythema dosages on five consecutive days. Periphera l blood was obtained before and after the procedure. Overall, there were no major effects of UVB irradiation on peripheral lymphocyte subsets and prol iferation of PBMC from patients or normal controls, but UVB irradiation led to a significant increase in PWM-stimulated production of IL-6, IL-2R and TNF by PBMC. These changes were independent of the individual UVB dosages a dministered and appeared in both groups similarly. UVB irradiation did not lead to significant changes on IL-1 and IL-2 expression by PBMC. Our result s suggest that PBMC participate in the cytokine response to UV, even in the absence of inflammatory reactions, but that this participation is not spec ific to MM patients.