Proportion of T follicular helper cells in peripheral blood of rheumatoid arthritis patients: a systematic review and meta-analysis.

Alterations in the levels and activity of Tfh may lead to impaired immune tolerance and autoimmune diseases. The aim of this study was to investigate the proportion and types of Tfh cells in the peripheral blood (PB) of RA patients.Comprehensive databases were searched for studies evaluating the proportion of Tfh cells in the PB of patients with RA compared to healthy control (HCs).The proportion of Tfh cells in RA patients was significantly higher than in HCs (SMD 0.699, [0.513, 0.884], p < 0.0001). Furthermore, Tfh cells proportion in untreated-RA and early-RA patients was markedly greater than HCs, when comparisons done without considering the definition markers, and also when Tfh cells were defined by the specified definition markers. While the proportion of Tfh cells by all definitions was higher in active-RA compared to HCs, analysis of two definitions, CD4CXCR5 and CD4CXCR5ICOS, didn't show significant differences. Furthermore, higher proportion of Tfh cells defined by all definitions and a specified definition (CD4CXCR5PD-1) was observed when SRA compared to SRA patients.The results demonstrate that circulating Tfh are highly elevated in RA patients highlights its potential use as a biomarker and a target for RA therapy.