PRTN3 and rheumatoid arthritis: We also describe two TPH CD4+ T-cell clusters expressing different levels of CXCL13. Finally, we find that TPH cells express the G-protein-coupled receptor GPR56, the inhibitory receptor LAG-3, and the tissue-resident memory (TRM) receptors CXCR6 and CD69 implicating that these T cells are maintained in the ACPA+ RA synovial joint.