CORRELATION OF UVC AND UVB CYTOTOXICITY WITH THE INDUCTION OF SPECIFIC PHOTOPRODUCTS IN T-LYMPHOCYTES AND FIBROBLASTS FROM NORMAL HUMAN DONORS

By using specific monoclonal antibodies in situ and a computer-assiste d image analysis system we have determined the relative induction of c yclobutane dimers, (6-4) photoproducts and Dewar isomers in human mono nuclear cells and fibroblasts following irradiation with UVC, broad-sp ectrum UVB and narrow-spectrum UVB. The lamps produced these lesions i n different proportions, with broad-spectrum UVB inducing a greater co mbined yield of (6-4) photoproducts and Dewar isomers per cyclobutane dimer than UVC or narrow-spectrum WE. The relative induction ratios of (6-4) photoproducts compared to cyclobutane dimers were 0.15, 0.21 an d 0.10 following irradiation with UVC, broad- or narrow-spectrum UVB, respectively. Although Dewar isomers were induced by UVC, their relati ve rate of formation compared to cyclobutane dimers was significantly greater after irradiation with either broad-spectrum or narrow-spectru m UVB. These values were 0.001, 0.07 and 0.07, respectively. With each lamp source, we have determined the survival of normal human T-lympho cytes and fibroblasts at fluences, which induce equivalent yields of c yclobutane dimers, (6-4) photoproducts or (6-4) photoproducts plus Dew ar isomers. Killing of fibroblasts appears to be associated with (6-4) photoproduct formation, whereas killing of T-lymphocytes seems to be mediated by combined (6-4) plus Dewar yields. These results emphasize the need to study the biological effects of UVB because cellular respo nses may be different from those following UVC irradiation.