TPH1 and rheumatoid arthritis: We and others have developed robust single-cell integration methods and identified specific RA-relevant immune populations (47, 51–55), including our recently identified GZMK+ CD8+ T cells (56), previously identified Tph and Tfh cells (46, 57), proinflammatory myeloid cells like IL-1B+HBEGF+ (46, 58), IFN- and TNF-driven CXCL10+CCL2+ macrophages (47), and NR4A+ B cells (59).