Inhibitory Effect of Interferon-γon the Response of Human Thyrocytes to Thyrotropin (TSH) Stimulation: Relationship Between the Response to TSH and the Expression of DR Antigen

Abstract

Thyroid epithelial cells (thyrocytes) in autoimmune thyroid disease have been found to express DR antigens on their surfaces, and interferon-γ (IFNγ) induces DR antigen expression. This study was undertaken to determine the effect of IFNγon the response of human thyrocytes to TSH stimulation and the relationship between the response to TSH and the expression of DR antigen induced by IFNγ,using monolayer cultures of Graves’ thyrocytes. When confluent thyrocyte monolayers were incubated with TSH or Bu2cAMP (DBcAMP) for 7-9 days, T₃ and thyroglobulin concentrations in the culture medium increased gradually in a dose-dependent manner. However,However, when TSH or DBcAMP was added after the cells had been cultured for 4 days with IFNγ, T₃ and thyroglobulin secretion in response to both 10 mU/mL TSH and 1 mM DBcAMP was significantly inhibited. The inhibition by IFN7 was dose dependent and correlated with the number of DR antigen-positive thyrocytes present on the last day of culture. IFNα and -β did not affect the response of thyrocytes to TSH or DBcAMP stimulation. These results suggest that DR antigen-positive thyrocytes fail to respond to TSH stimulation at a site located distal to cAMP formation. (J Clin Enddcrinol Metab 64: 949,1987)