Allospecific Dr Gene Expression on the Human Thyroid Cell

Human thyroid epithelial cells, stimulated with recombinant gamma interferon (IF) (100U/ml), were HLA-DR typed by means of antibody-dependent, complement-mediated cytotoxicity. The thyroid cell lysis reaction patterns were found to be similar to those obtained with autologous peripheral B cells in four of five separate experiments. Since the cytotoxic reactions with thyroid cells were sometimes incomplete with many antisera, a two-color fluorescence technique was developed to measure the specificity of the antibody-dependent, complement-mediated lysis. Using constitutively HLA-D antigen-positive Raji B lymphoblastoid cells as controls, we showed that non-polymorphic HLA-D and HLA-DR determinants could be detected on the thyroid cell surfaces by this cell lysis approach. In addition, gamma IF stimulated thyroid cells from a DR3 positive individual were lysed to a significantly greater degree than unstimulated autologous thyroid cells with the use of a specific monoclonal antibody to HLA-DR3, thus confirming the original HLA typing studies. These data demonstrate, for the first time, that the expression of HLA-DR antigen on the surface of human thyroid cells is allospecific and may, therefore, play an important role in the immunopathology of autoimmune thyroid disease.