Selective activation of naïve B cells with unique epitope specificity shapes autoantibody formation in celiac disease.

Many antibody responses induced by infection, vaccination or autoimmunity show signs of convergence across individuals with epitope-dependent selection of particular variable region gene segments and complementarity determining region 3 properties. However, not much is known about the relationship between antigen-specific effector cells and antigen-specific precursors present in the naïve B-cell repertoire. Here, we sought to address this relationship in the context of celiac disease, where there is a stereotyped autoantibody response against the enzyme transglutaminase 2 (TG2). By generating TG2-specific monoclonal antibodies from both duodenal plasma cells and circulating naïve B cells, we demonstrate a discord between the naïve TG2-specific repertoire and the cells that are selected for autoantibody production. Hence, the naïve repertoire does not fully reflect the epitope preference and gene usage observed for memory B cells and plasma cells. Instead, distinct naïve B cells that target particular TG2 epitopes appear to be selectively activated at the expense of TG2-binding B cells targeting other epitopes.