Figure 2: Differentiation of naïve T cells into pathogenic effector T cells. APCs can be activated by numerous factors, resulting in the release of cytokines that promote the differentiation of naïve T cells into various subsets of pathogenic effector T cells that drive inflammation, tissue injury, and autoantibody production. Segmented filamentous bacteria (SFB) can also promote the development of Th17 cells and autoimmune responses in vivo. Proinflammatory cytokines derived from both innate and adaptive immune cells attenuate TREG cell-mediated suppression of effector T cells.