In vitro release of activin A from human normal and pathological thyroid tissues.

Activin A is a dimeric glycoprotein belonging to the transforming growth factor beta (TGF-beta) superfamily characterized by the ability to affect FSH secretion. Activin A was originally indicated as a gonadal product but the expression of activin A has been successively identified in several different tissues, including the thyroid gland. The aim of this study was to evaluate the release of activin A from human normal and pathological thyroid tissues in culture. Activin A concentration was evaluated in media obtained from primary culture of perinodular normal tissues (no.=2), hyperplastic hyperfunctioning thyroid tissues due to Graves' disease (no.=3) and autonomous thyroid adenomas (no.=3). Detectable levels of activin A were found in the incubation media from all tissues, without significant differences between normal and pathological samples. We conclude that activin A is secreted by follicle thyroid cells in normal and pathological conditions.