HLA-DRB5 and rheumatoid arthritis: Among them, HLA-DRB5+ and HLA-DRB5+HOPX+ memory B cells, which were absent in more than half (four of seven) of STs from ACPA- RA patients, shared common highly expressed genes (GPR183 and HLA-DRB5) and distinct HOPX expression in HLA-DRB5+HOPX+ memory B cells (Fig. 2d–f, Supplementary Fig. 3b).