INTERFERON-GAMMA REDUCES THE THYROID PEROXIDASE CONTENT OF CULTURED HUMAN THYROCYTES AND INHIBITS ITS INCREASE INDUCED BY THYROTROPIN

To clarify the role of interferon-gamma (IFN-gamma) in autoimmune thyroid diseases, we investigated the effects of IFN-gamma on the content of thyroid peroxidase (TPO) and the expression of HLA-DR antigens in cultured normal human thyrocytes. The effect of TSH on the action of IFN-gamma was investigated. Immunofluorescence staining and photometric analysis showed that IFN-gamma not only induced the expression of DR antigen, but also reduced the content of TPO in a concentration-dependent manner. The addition of TSH increased the content of TPO and enhanced the IFN-gamma-induced expression of DR antigen. IFN-gamma also inhibited the increase in TPO content induced by TSH. Thus, complex interactions appear to exist between IFN-gamma and TSH or thyroid-stimulating antibodies in the modulation of hormone secretion and autoimmune phenomena in the thyroid.