TNF and rheumatoid arthritis: It was reported that Treg cells from patients with active RA can suppress the proliferation of Teff cells, but the ability of Treg cells to inhibit proinflammatory cytokine production, such as production of interferon‐γ (IFNγ) and tumor necrosis factor (TNF) by T cells and production of TNF by monocytes, is impaired 13.