IL4 and rheumatoid arthritis: After a 96 h culture, CSR to IgA in miR-146a–/– B cells was significantly increased as compared to miR-146+/+ B cells (27.0% vs 19.3% upon stimulation by LPS plus IL-4, IL-5, TGF-β, anti-δ mAb and RA; 26.6% vs 18.4% upon stimulation with CD154 plus IL-4, IL-5, TGF-β, anti-δ mAb and RA) (Figure 5A).