ULTRAVIOLET-B IRRADIATION MODULATES THE IMMUNE-SYSTEM OF FISH (RUTILUS-RUTILUS, CYPRINIDAE) - I - PHAGOCYTES

Roach (Rutilus rutilus) were irradiated with a single dose of ultravio let B (UVB) radiation (0.4 J/cm(2)) in order to study the effects of U VB on the nonspecific immune defense mechanisms of fish. Neutrophils a nd macrophages were isolated from the head kidney of fish on days 1-14 postirradiation, Both random and directed migration of neutrophils, s tudied by migration under agarose assay, were suppressed on day 1 afte r UVB irradiation. The respiratory burst of phorbol 12-myristate 13-ac etate-stimulated neutrophils and macrophages was also suppressed at da ys 1 and 2 after UVB irradiation. The suppression of migration and res piratory burst were restored or the responses were even enhanced later , but on the other hand spontaneous cytotoxicity of neutrophils toward (51)chromium-labeled K562 target cells stayed suppressed throughout t he 14 day follow-up. This study indicates that UVB radiation has the p otential to suppress the functioning of phagocytes and to compromise t he immune system of fish.