The release of the immunologically active cytokine interleukin-6 (IL-6) by cultured anterior pituitary cell aggregates was found to increase with the age of the donor rats. The glucocorticoid hormone dexamethasone (DEX) dose-dependently inhibited the release of IL-6, the IC50 being 2.43 +/- 0.93 nM. The sex steroids dihydrotestosterone and estradiol were without detectable effect. The adenylate cyclase activator forskolin increased IL-6 release in aggregate cultures in the presence of DEX. It is concluded that IL-6 release by anterior pituitary cells is subject to developmental changes and under regulatory control of biologically active substances.