Interferon-alpha (IFN alpha) may exert direct inhibitory effects on cell
proliferation and on the production of different peptide hormones. We
investigated the effect of IFN alpha on hormone production by 15
GH-secreting pituitary adenomas, 4 clinically nonfunctioning or
gonadotroph pituitary adenomas, and 4 prolactinomas in vitro. In the
GH-secreting pituitary adenoma cultures, a short term (72-h) incubation
with IFN alpha (50-100 U/mL) significantly inhibited GH secretion in 3 of
7 cases and PRL secretion in 6 of 7 cultures. During prolonged incubation
(14 days) with IFN alpha, GH and/or PRL secretion was significantly
inhibited in 7 of 8 cultures (GH, 17-78% inhibition; PRL, 39-88%
inhibition). In the clinically nonfunctioning or gonadotroph cultures
