In vitro cellular interactions among thyrocytes, T cells and monocytes from patients with Graves' disease

In order to investigate the cellular interactions among thyrocytes, T cells and monocytes in thyroid glands from patients with Graves' disease, we determined alterations of HLA-DR antigen expression on thyrocytes and T cells, and the production of interferon-gamma during coculture of thyrocytes, T cells and monocytes obtained from patients with Graves' disease. Thyroid glands were obtained at operation from 17 patients with Graves' disease. When thyrocytes and autologous peripheral blood T cells were cocultured for 7 days, the percentage of HLA-DR antigen expression on thyrocytes was significantly increased by T cells and that on T cells was also significantly increased by thyrocytes. Addition of autologous monocytes to the mixtures of thyrocytes and T cells significantly increased the expression of HLA-DR antigens on both thyrocytes and T cells compared with mixtures without monocytes. In culture supernatants, interferon-gamma was detected in 4 of 14 cocultures of thyrocytes and T cells, in 5 of 10 cocultures of thyrocytes, T cells and monocytes, but not in any cultures of thyrocytes alone, T cells alone and T cells and monocytes. Induction of HLA-DR antigen expression on thyrocytes and T cells was blocked by addition of anti-interferon-gamma monoclonal antibody to the mixture. These results suggest that HLA-DR antigen positive thyrocytes are able to induce the HLA-DR antigen expression of T cells in the presence of monocytes, and the activated T cells are capable of producing interferon-gamma which acts on thyrocytes to induce and maintain the expression of HLA-DR antigens.