High frequencies of activated B cells and T follicular helper cells are correlated with disease activity in patients with new‐onset rheumatoid arthritis

Summary This study aimed to examine the frequency of different subsets of circulating B and T follicular helper ( T fh) cells in patients with new‐onset rheumatoid arthritis ( RA ) and following standard therapies. Twenty‐five RA patients and 15 healthy controls ( HC ) were recruited for characterizing the frequency of CD 27 + , immunoglobulin ( Ig)D + , CD 86 + , CD 95 + , Toll‐like receptor ( TLR )‐9 + B cells and inducible T cell co‐stimulator ( ICOS ) and programmed death 1 ( PD ‐1)‐positive T fh cells and the level of serum interleukin ( IL )‐21. The potential correlation between the frequency of different subsets of B and T fh cells and the values of clinical measures in RA patients was analysed. In comparison with HC , significantly higher percentages of circulating IgD + CD 27 − CD 19 + naive B , CD 86 + CD 19 + and CD 95 + CD 19 + activated B , CD 3 + CD 4 + CXCR 5 + , CD 3 + CD 4 + CXCR 5 + ICOS + , CD 3 + CD 4 + CXCR 5 + PD ‐1 + and CD 3 + CD 4 + CXCR 5 + ICOS + PD ‐1 + T fh cells but lower IgD + CD 27 + CD 19 + preswitch memory B cells were detected, accompanied by significantly higher levels of serum IL ‐21 in the RA patients. Furthermore, the percentages of CD 95 + B cells were correlated positively with the frequency of PD ‐1 + T fh cells, but negatively with ICOS + T fh cells. The percentages of CD 86 + B cells and ICOS + T fh cells were correlated positively with the values of disease activity score 28 ( DAS 28). Following the drug therapies for 1 month, the percentages of CD 86 + B and PD ‐1 + T fh cells were reduced significantly in the drug‐responding patients. Our data suggest that activated B and T fh cells may contribute to the pathogenesis of RA and the frequency of activated B and T fh cells may be used as biomarkers for evaluating the therapeutic responses of individual patients with RA .