Interferon-gamma induces HLA-DR expression by thyroid epithelium.

We recently showed that human thyroid epithelial cells, which are normally negative for HLA-DR molecules, express HLA-DR in thyroid autoimmunity. Furthermore, induction of HLA-DR on normal thyroid cells can be achieved by culture with plant lectins. We have now found that recombinant human interferon-gamma (IFN-gamma) induces expression of HLA-DR molecules on cultured human thyroid cells, whereas Namalva IFN-alpha, recombinant IFN-beta or recombinant interleukin-2 (IL-2) do not. All three IFN, but not IL-2, enhanced thyroid cell HLA-A,B,C expression. The results strongly implicate T cells (which are the source of IFN-gamma) in the aberrant induction of DR on thyroid epithelial cells which is proposed to be a central feature of the immunopathological processes leading to autoimmunity.