Toward addressing this postulated miR-146a modulatory function on CSR to IgA, C57BL/6 mouse B cells were stimulated with LPS or CD154 plus IL-4, TGF-β with or without RA, as well as human B cells with CD154 or CpG plus TGF-β to induce CSR to IgA. This evidence concerns the gene TGFB1 and rheumatoid arthritis.