The interaction between interleukin-1 and glucocorticoids in the in vivo antibody response of mice to three concentrations of antigen.

Antigenic challenge leads to a transient increase of serum glucocorticoids, a phenomenon that has been implicated in regulation of the magnitude of the immune response. In the present study, we determined the effects of immunization with three different doses of the T-dependent antigen, sheep red blood cells (SRBC), on glucocorticoid levels, IL-1 production by splenic macrophages, and number of splenic antibody-forming cells in mice. Immunization with three doses of antigen caused a dose-dependent increase in serum glucocorticoid after 2-4 h. No effect of immunization on serum corticosteroid-binding globulin levels was found, suggesting that the concentration of free, hormonally active corticosterone was increased. Antigenic challenge resulted in a significant rise of IL-1 production in a dose-related manner 2 h after immunization, except for the group given the highest dose of SRBC, which demonstrated strong elevation of serum corticosterone level by this time. However, IL-1 production by splenic macrophages, isolated at the peak of the hormonal reaction to SRBC (4 h after immunization), was suppressed in a dose-dependent fashion. An inverse relationship between endogenous levels of glucocorticoids and splenic plaque-forming cells number was also revealed. It is concluded that the interaction of IL-1 and glucocorticoids during the first hours after antigenic challenge is one of the factors controlling the magnitude of the immune response.