The specificity of increased IgA CSR in miR-146a–/– B cells stimulated by LPS or CD154 plus IL-4, IL-5, TGF-β, anti-δ mAb and RA was emphasized by the increased germline Iα-Cα transcripts, post-recombination Iμ-Cα transcripts, post-recombination circle Iα-Cμ transcripts and increased IgA secretion as compared to miR-146a+/+ B cells, as well as by the unchanged IgG1 secretion, and germline Iγ1-Cγ1 and Iε-Cε transcripts in the very miR-146a–/– B cells (Figures 5B, C). This evidence concerns the gene TGFB1 and rheumatoid arthritis.