Cortisol mediated suppression of salmonid lymphocyte responses in vitro.

The suppressive activity of cortisol on the in vitro induction of coho salmon (Oncorhynchus kisutch) B cell activation was examined. Suppression was observed with splenic and pronephric (anterior kidney) derived lymphocytes. The kinetics of cortisol-induced suppression revealed distinct differences in the sensitivity of splenic and pronephric lymphocytes. Pronephric lymphocytes were only sensitive to cortisol early in the induction of the antibody response, whereas the splenic cells were sensitive to cortisol throughout the culture period. Addition of supernatants from antigen stimulated pronephric cultures completely restored the ability of pronephric lymphocytes to produce an antibody response, suggesting that this glucocorticoid-suppression may be mediated by inhibition of lymphokine production.