Human isletβcells do not express HLA Class II normally, yet, in the diabetic pancreas,βcells are selectively positive for Class II and this may facilitate their recognition by T cells. It has been demonstrated that humanβcells can be induced to express Class II when cultured with IFN-γ+ TNF-αor IFN-γ+ TNF-β. To assess whether or not they can be induced to express the products of the Class II subregions, DR, DP and DQ, human islet cultures from 10 pancreases were supplemented with the combination of IFN-γ+ TNF-αusing MoAbs specific for DR, DP and DQ products, and antibodies to insulin and glucagon. The combination IFN-γ+ TNF-α(100–1000 U/ml each) was able to induce the expression of the three subregions in bothβandαcells. The induction of subregion expression followed the hierarchy DR>DQ⩾DP. The capability ofβcells to express all three Class II subregions supports the possibility that these cells can present their self antigens to T cells.