TPH1 and autoimmune disease: Among them, Tph2 and Tph1–17 subsets expressed only low level of IL21 and offer less help to B cells; Tph2 presents a cytotoxicity related transcripts correlated with their alignment of severity and activity of autoimmune disease (131); SLE patients exhibit increased Tph1/Tph2 frequencies positively linked to SLEDAI scores, with Tph1 enrichment in cutaneous/musculoskeletal involvement and Tph2 in lupus nephritis (132), suggesting the different roles Tph subsets play across the system of SLE.