Thus, in addition to confirming the association of the TPh and Th1 subsets with RA SF, our results show that a substantial proportion of CXCR3+ Th cells in RA SF are non-classical Th cells and that proportions of CXCR3+Th2 and PD-1highTFh cells were higher in RA SF compared to paired blood. Here, TPH1 is linked to rheumatoid arthritis.