TNF and type 1 diabetes mellitus: Consequently, we speculated that interleukin 1β (IL-1β), interferon γ (IFN-γ), and tumor necrosis factor α (TNF-α), which are proinflammatory cytokines produced by antigen-producing cells and T cells during T1D and are present in the inflamed islets, may influence the expression of integrin α4β7 (Figure 6A).