The effect of ultraviolet B irradiation, cis-urocanic acid and tumour necrosis factor-alpha on delayed hypersensitivity to herpes simplex virus

Abstract

Previously it has been shown that ultraviolet-B (UVB) irradiation or cis-urocanic acid (cis-UCA) treatment of mice before infection with herpes simplex virus (HSV) suppressed the delayed hypersensitivity (DH) response when the mice were subsequently challenged with inactivated virus. In the present study, the time course of the elicitation phase of the DH was examined, and it was found to be biphasic with one peak 1 h following challenge and a second at 24 h. Both UVB irradiation and cis-UCA treatment of mice before infection with HSV significantly suppressed the DH at 1 h as well as at 24 h. The role of tumour necrosis factor-alpha (TNF-alpha) in the suppression was tested by injecting mice intraperitoneally with neutralizing TNF-alpha antibodies 2 h before UVB irradiation or cis-UCA treatment followed by infection with HSV. This had no effect on the suppression of DH to HSV induced by cis-UCA but significantly reduced that generated by UVB exposure. Thus, the mechanism of suppression of DH induced by UVB irradiation or cis-UCA may be different.