Effects of short-wave ultraviolet radiation (UV-C) on delayed hypersensitivity in the guinea-pig

Guinea-pigs, previously sensitized to dinitrochlorobenzene (DNCB), were exposed to varying doses of UV-C radiation (254 nm) on one of the flanks for a period of 15 days. They were then patch-tested with DNCB immediately after UV treatment. The responses to DNCB were diminished both in the irradiated and non-irradiated skin compared with control animals which had not received UV-C radiation. This effect was dose dependent and could only be demonstrated for a limited period of time. Guinea-pig exposed to UV-C radiation did not show a decreased response to sodium lauryl sulphate, which is a potent irritant. The influence of UV-C on delayed hypersensitivity therefore seems to be an immunological effect.