The novel application of an immunological technique reveals the immunosuppressive effect of phytoestrogens in Betta splendens

The novel application of a standard technique to assess cell-mediated immune response to phytohaemagglutinin (PHA) injected in the caudal peduncle in a small fish (< 2 g) to test the immunosuppressive effect of three phytoestrogens: genistein, equol and beta-sitosterol is described. Individual Betta splendens exposed to these oestrogenic chemicals produced weaker inflammatory responses to PHA than did control individuals, suggesting that phytoestrogens are immunosuppressive. This technique should enable immune function in fish species, too small to provide sufficient blood for conventional immunological measures, to be assessed. (c) 2006 The Fisheries Society of the British Isles.