The effects of ultraviolet irradiation on the generation of anti-tumor cytotoxic effector cell responses in vitro.

Abstract

The effects of irradiation of lymphoid cells in vitro with ultraviolet (UV) light were studied using radiation sources that are widely used both in the study of photocarcinogeneic mechanisms and by commercial tanning parlors (FS40 sunlamps). Low doses of direct exposure of cells was found to abrogate the differentiation events that lead to the generation of functional cytotoxic T lymphocytes (CTL). UV irradiation of cells in vitro induces alterations that, although not immediately obvious, lead to cell death during the next several days in tissue culture. Energy titration experiments demonstrated that both primed T cells and accessory cells were sensitive to the effects of direct UV-exposure; T cells were found to be much more sensitive than accessory cells. A 90% decrease in CTL generation could be affected with as little as 10 sec of UV exposure. These effects appear to be caused by wavelengths in the UVB range (280 to 320 nm), since exposure of cells to much higher doses of energy in the UVA range (320 to 400 nm) were not inhibitory. The spectrum of wavelengths in the UV region is large (200 to 400 nm). The data presented here demonstrate that it is overly simplistic to assume that all wavelengths in the UV spectrum mediate their effects via identical mechanisms. Furthermore, the wavelengths at which a given amount of energy is emitted appears to be much more important than the absolute amount of energy (in joules) which biologic systems are subjected.