Effects of short-wave ultraviolet light (UVB) on delayed hypersensitivity in the guinea pig.

Guinea pigs, previously sensitized to dinitrochlorobenzene (DNCB), were exposed to varying doses of UVB radiation on the right flank for a period of 12 days. The response to an elicitation dose of DNCB was diminished in the irradiated skin immediately after UV treatment. This effect was dose-dependent. No reduction in the response could be demonstrated in unexposed skin. One week after UVB treatment the response to DNCB was increased, and after 2 weeks there was a normal eczematous reaction after application of DNCB.