Expression of misfolded HLA class I on CHO cells induced by HLA-DR. Wild-type HLA-Cw*04:01, HLA-Cw*03:04, HLA-A69:01 and HLA-B15:01 plasmids were transiently transfected into CHO cells with GFP plasmids in the presence (HLA-DR) or absence (Mock) of HLA-DRαβ (01:01) plasmids. Expression of misfolded HLA class I (HC10 mAb, thick lines, upper panel) and HLA-DR (thick lines, lower panel) on GFP-positive cells is shown. Control staining: shaded histograms. Data are representative of three independent experiments.