ACTION SPECTRUM FOR CYTOTOXICITY IN THE UVA-WAVELENGTH AND UVB-WAVELENGTH REGION IN CULTURED LENS EPITHELIAL-CELLS

Purpose. This study was done to quantitate the biologic effects of dif ferent wavelengths of radiation in the UVA- and UVB-wavelength region on cultured rabbit lens epithelial cells. Methods. An action spectrum for UV-induced cytotoxicity as measured by colony-forming ability was determined using six different monochromatic wavelengths from 297 to 4 05 nm in rabbit lens epithelial cell line N/N1003A. Cell survival was determined by clonogenic assay. Fluence rates were monitored with a ca librated radiometer. Results. Survival curves show that cell killing w as most efficient at 297 nm. After quantum correction, the efficiency of 297-nm radiation in cell killing was 7 times greater than was 302-n m radiation. Radiation at 297 nm was more than 170, 340, 560, and 2000 times as effective in cell killing as 313-, 325-, 334-, and 365-nm ra diation, respectively. The action spectrum had a shape similar to the DNA absorption spectrum in the UVB region, suggesting that DNA may be one of the critical targets for damage to the cells. At wavelengths lo nger than 313 nm, the shape of the action spectrum deviated from the D NA absorption spectrum. Conclusions. Cytotoxicity of UV radiation in c ultured lens epithelial cells varies greatly with wavelength within th e UVA and UVB regions. Different mechanisms may predominate in the two wavelength regions. Cultured cells may provide a suitable system for investigating the mechanisms by which UV radiation damages lens epithe lial cells and leads to cataract formation.