CD4 and Autoimmunity: Interestingly, RXRA-mediated signaling enhances differentiation of functionally competent CD4+ regulatory T cells and potently inhibits the formation of CD4+ T helper 17 cells, the latter of which have been strongly implicated in various autoimmune pathologies, including MS [6, 15, 18, 19, 22, 39, 62, 78].