SRP309630 PRJNA707309 GSE168407 A follicular regulatory innate lymphoid cell population impairs interactions between germinal center Tfh and B cells Here we show a newly identified human Innate Lymphoid Cell population present in the follicles of tonsils and lymph nodes termed follicular regulatory ILCs (ILCFR). ILCFR have a distinct phenotype and transcriptional program when compared to other defined ILCs. Surprisingly, ILCFR inhibit the ability of follicular helper T (Tfh) cells to provide B cell help. The localization of ILCFR to the germinal centers suggests these cells may interfere with germinal center B cell (GC-B) and germinal center Tfh cell (GC-Tfh) interactions through the production of transforming growth factor beta (TGF-b). Intriguingly, under conditions of impaired GC-Tfh-GC-B cell interactions, such as human immunodeficiency virus (HIV) infection, the frequency of these cells is increased. Overall, we predict a role for ILCFR in regulating GC-Tfh-GC-B cell interactions and propose they expand in chronic inflammatory conditions. Overall design: 7 individual human tonsil samples of 7 different cell poulations were collected for each tonsil GSE168407 pubmed 33980982