biostudies-literatureDelacher MEuropean Research Council1621https://www.ebi.ac.uk/biostudies/studies/S-EPMC6453958biostudies-literatureUnknown10(1)The transcriptional regulator Rbpj is involved in T-helper (T_H) subset polarization, but its function in T_reg cells remains unclear. Here we show that T_reg-specific Rbpj deletion leads to splenomegaly and lymphadenopathy despite increased numbers of T_reg cells with a polyclonal TCR repertoire. A specific defect of Rbpj-deficient T_reg cells in controlling T_H2 polarization and B cell responses is observed, leading to the spontaneous formation of germinal centers and a T_H2-associated immunoglobulin class switch. The observed phenotype is environment-dependent and can be induced by infection with parasitic nematodes. Rbpj-deficient T_reg cells adopt open chromatin landscapes and gene expression profiles remiNature communicationsRbpj expression in regulatory T cells is critical for restraining T_H2 responses.PMC6453958648145Brunk FImbusch CDDelacher MHielscher TBreloer MBittner SHerzig YGrone HJFeuerer MHotz-Wagenblatt ASchmid RMTrager UHofer ACWeichenhan DFederico GRehli MSchmidl CKagebein DAbramson JHartmann WBreiling AfalseRbpj expression in regulatory T cells is critical for restraining T_H2 responses.The transcriptional regulator Rbpj is involved in T-helper (T_H) subset polarization, but its function in T_reg cells remains unclear. Here we show that T_reg-specific Rbpj deletion leads to splenomegaly and lymphadenopathy despite increased numbers of T_reg cells with a polyclonal TCR repertoire. A specific defect of Rbpj-deficient T_reg cells in controlling T_H2 polarization and B cell responses is observed, leading to the spontaneous formation of germinal centers and a T_H2-associated immunoglobulin class switch. The observed phenotype is environment-dependent and can be induced by infection with parasitic nematodes. Rbpj-deficient T_reg cells adopt open chromatin landscapes and gene expression profiles remi2019-01-01T00:00:00Z2019 Apr2026-05-04T09:52:25.286Z2025-05-18T11:07:37.887ZS-EPMC64539583096245410.1038/s41467-019-09276-w