IL6 and rheumatoid arthritis: Other studies using MH7A cells have shown synergistic effects of interleukin 1β (IL-1β) and 1,25-(OH)2D3 in suppressing the production of IL-6 and TNFβ levels, and Th17-inducing cytokines (IL-1β, IL-6 and IL-23) synergistically enhanced the pro-regulatory effect of 1,25-(OH)2D3 on T cell phenotype [136], further emphasising important interactions between 1,25-(OH)2D3 and pro-inflammatory cytokines in RA [157].