Chicken Serum Inhibits Lectin-Induced Proliferation of Autologous Splenic Mononuclear Cells 1

Abstract

Abstract

Splenic mononuclear cells (SMC) proliferate well in response to phytomitogens in serum-free medium. Low concentrations of corticosterone significantly inhibit both spontaneous (1 ng/ml) and phytohemagglutinin-induced proliferation (12 ng/ml) of chicken SMC. Addition of as little as 3% normal heat-inactivated chicken serum to both autologous and heterologous suspensions of chicken SMC causes a 50% inhibition in lectin-induced proliferation. This suppression by normal chicken serum increases in a dose-dependent manner. Inhibition of DNA synthesis by chicken serum is not due to endogenous corticosterone because charcoal stripping of the serum to deplete glucocorticoids does not remove the immunosuppression. Chicken serum is not cytotoxic to lymphoid cells. These data demonstrate that low, physiologic concentrations of corticosterone inhibit proliferation of chicken SMC. Utilization of a serum-free culture system also permitted the identification of a serum factor that appears to be even more immunosuppressive than corticosterone. Since this factor inhibits the lectin-induced proliferation of both autologous and heterologous avian lymphoid cells, it may be a very important naturally occurring immunoregulatory compound.