IL21 and rheumatoid arthritis: Interestingly, neutralization of both, IL-21 and IL-23 in RA CD4+ T cells not only yielded significant reduction in the expression of inflammatory cytokines TNF-α, IL-17 and IFN-γ, but also downregulated RANKL expression, directly indicating towards the critical role played by these cytokines in augmenting the inflammatory response as well as RANKL expression.