Fig. 6

Correlation between circulating follicular helper T (Tfh) or follicular regulatory T (Tfr) cell frequency and the Disease Activity Score in 28 joints based on C-reactive protein (DAS28-CRP). The circulating Tfr cell frequency was negatively correlated with DAS28-CRP (r = − 0.337, P = 0.025) (a), while the Tfh/Tfr ratio was positively correlated with DAS28-CRP (r = 0.510, P < 0.001) (b)