Immunomodulatory effects of alpha melanocyte stimulating hormone on common carp (Cyprinus carpio L.)

The immunomodulatory effects of phagocytic cells in common carp Cyprinus carpio L., by alpha melanocyte stimulating hormone (α-MSH) was analyzed in vitro. Carp head kidney leucocytes were cultured in RPMI 1640 medium containing 0.05, 0.1, 1 and 10 nM α-MSH and the production of superoxide anion was measured via the reduction of nitroblue tetrazolium (NBT) in vitro. Macrophages incubated with α-MSH showed an increase in the production of superoxide anion in comparison to control macrophages cultured without hormone. Phagocytic cells treated with α-MSH also displayed increased phagocytosis. Furthermore, carp lymphocytes treated with α-MSH increased the mitogenic responses to phytohaemoagglutinin (PHA-P). These results show that α-MSH directly influences fish immune responses.