Fig. 4.

Autoantibody binding to IgGH complexed with HLA-DR molecules is different between RA-susceptible and RA-resistant alleles. (A and C) The IgGH and GFP were cotransfected together with HLA-DR into 293T cells in the presence (red lines) or absence (blue lines) of Ii (A) or HLA-DM (C), and surface expression of HLA-DR and IgG and binding of autoantibodies in the RF standard serum on GFP-positive cells were analyzed. Cells transfected with the IgGH alone were stained as a control (shaded histograms). Expression of Ii (A) or HLA-DM (C) was analyzed by intracellular staining. (B) Flag-tagged cysteine mutant HEL and HLA-DR were cotransfected with GFP in the presence (red lines) or absence (blue lines) of Ii. The transfectants were stained with anti-Flag and anti–HLA-DR mAbs, and expression on GFP-positive cells was determined. Cells transfected with mutHEL alone were stained as a control (shaded histograms). Data are representative of at least three independent experiments.