THE EFFECT OF ULTRAVIOLET-B IRRADIATION, CIS-UROCANIC ACID AND TUMOR-NECROSIS-FACTOR-ALPHA ON DELAYED-HYPERSENSITIVITY TO HERPES-SIMPLEX VIRUS

Previously it has been shown that ultraviolet-B (UVB) irradiation or c is-urocanic acid (cis-UCA) treatment of mice before infection with her pes simplex virus (HSV) suppressed the delayed hypersensitivity (DH) r esponse when the mice were subsequently challenged with inactivated vi rus. 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 c is-UCA treatment of mice before infection with HSV significantly suppr essed the DH at 1 h as well as at 24 h. The role of tumour necrosis fa ctor-alpha (TNF-alpha) in the suppression was tested by injecting mice intraperitoneally with neutralizing TNF-alpha antibodies 2 h before U VB irradiation or cis-UCA treatment followed by infection with HSV. Th is had no effect on the suppression of DH to HSV induced by cis-UCA bu t significantly reduced that generated by UVB exposure. Thus, the mech anism of suppression of DH induced by UVB irradiation or cis-UCA may b e different.