HLA-DRB1 and type 1 diabetes mellitus: Using HLA class II tetramers for proinsulin epitopes presented by HLA-DR4 molecules, we purified antigen-specific autoreactive CD4 T cells from both control and T1D HLA-DRB1*04:01 subjects with different INS VNTR genotypes, and compared transcriptional profiles for NR4A and related gene families.