Nuclear proteins acquiring Germinal Center B cells are specifically suppressed by follicular regulatory T cells

Follicular regulatory T cells (Tfrs) restrict development of autoantibodies and autoimmunity while supporting high-affinity foreign antigen-specific humoral response. However, whether Tfrs can directly repress germinal center (GC) B cells that acquire auto-antigens is unclear. Moreover, TCR specificity of Tfrs to self-antigens is not known. Our study suggests that nuclear proteins contain antigens specific to Tfrs. Targeting of these proteins to antigen-specific B cells triggers rapid accumulation of Tfrs with immunosuppressive characteristics. Tfrs then exert negative regulation of GC B cells with predominant inhibition of the nuclear protein-acquiring GC B cells, suggesting an important role of direct cognate Tfr-GC B cells interactions for the control of effector B cell response.