Effects of steroids on the antibody producing activity of lymphocytes in rainbow trout

Abstract

The effects of steroid hormones on in vitro antibody producing cells from lymphocytes of the peripheral blood, head kidney, spleen and skin in juvenile rainbow trout were examined by ELISPOT assay. Cortisol, testosterone, estradiol-17β and 11-ketotestosterone reduced dose-dependently the number of cells producing both IgM and specific antibody against TNP-LPS. These steroid hormones also reduced IgM secretion from the head kidney and spleen lymphocytes. These results show that the low immunocompetence with the gonadal maturation is caused by the direct effects of steroid hormones on the antibody producing activity of lymphocytes. Moreover, the results also suggest that steroid hormones suppress the function of B lymphocytes, since TNP-LPS is thought to be thymus-independent antigen.