The effects of recombinant preparations of human interleukin-1 (IL-1) on basal and follitropin (FSH)-stimulated aromatase activity of immature rat Sertoli cells in vitro were studied. Sertoli cells were isolated from 7- to 10-day-old rats and cultured for 72 h at 32 degrees C in the presence or absence of test materials. The cells were then washed and cultured for a further 24 h with different doses of FSH in the presence or absence of IL-1. Neither IL-1 alpha nor IL-1 beta had any effect on basal aromatase activity. IL-1 beta inhibited FSH-stimulated aromatase activity in a dose-dependent manner while IL-1 alpha had no significant effect. The inhibitory influence of IL-1 beta on FSH-stimulated aromatase activity was greater when IL-1 beta was present in low concentrations (0.5 and 1.0 U) during the initial 72 h culture period and a further 24 h incubation with IL-1 beta did not cause a further inhibition. When the cells were cultured for 72 h in the presence of both IL-1 alpha and IL-1 beta, the inhibition of FSH-stimulated aromatase was higher than that obtained with IL-1 beta alone. The inhibitory activity of IL-1 beta was blocked by a specific IL-1 beta antiserum. Furthermore, IL-1 beta caused a significant inhibition of cAMP production in Sertoli cells and did not influence dibutyryl-cAMP-stimulated aromatase activity under identical experimental conditions.(ABSTRACT TRUNCATED AT 250 WORDS)