The cytotoxic and mutagenic effects of UVA radiation on L5178Y mouse lymphoma cells

A broad-band UVA source that emits primarily 350-400 nm radiation and no measurable radiation below 340 nm was used to test toxicity and mutagenicity at the thymidine kinase locus in L5178Y, subclone 3.7.2C(TK+/-) mouse lymphoma cells. Cells were exposed to a fluence of 0 to 80 x 104 J/m2. The relationship between UVA fluence and survival was found to have a shoulder region followed by an exponential decrease in survival at higher fluence levels. An exposure-dependent increase in mutation was observed with increasing fluences from 0 to about 60 x 104 J/m2. An approximately 3- to 4-fold increase in mutations (trifluorothymidine resistance) over unexposed, control cells was seen at a fluence that resulted in 90% cell killing. We conclude that UVA radiation is a mutagen in the L5178Y mouse lymphoma cells used in this study. (author)