Interferon-gamma inhibits thyroid-stimulating hormone-induced morphological changes and induces the expression of major histocompatibility complex class II antigen in thyroid follicles in suspension culture.

The effects of interferon-gamma (IFN gamma) on the morphology of thyroid follicles and the expression of major histocompatibility complex (MHC) class II antigens were examined. The thyroid follicles were suspended in RPMI-1640 containing 10% fetal calf serum with or without IFN gamma (200 U/ml). After culture for 5 days, follicles were incubated in the presence of TSH (10 mU/ml) for 1 h and fixed for electron microscopic and immunohistochemical examination. Regardless of the presence of IFN gamma, suspended follicles became inverted within 5 days. However, MHC class II antigens were expressed only in inverted follicles cultured with IFN gamma. In inverted follicles cultured without IFN gamma, TSH stimulation induced remarkable morphological changes, such as elongation of microvilli and an appearance of pseudopods. On the other hand, the follicles cultured with IFN gamma showed poor response to TSH. Thus, IFN gamma induced the expression of MHC class II antigens of cultured thyroid follicles and inhibited TSH-induced morphological changes in the cells.