IL6 and rheumatoid arthritis: Therefore, it is not surprising that mice lacking Csf2, Il23a, Il6 and Il17 were shown to be protected from CIA (76–79), and blocking these genes or their receptors with mAbs is highly efficacious in RA patients enrolled in clinical trials (68, 80–82), in addition to the already approved IL6R mAb tocilizumab (82).