CD4 and autoimmune disease: The 1,25(OH)2D3 together with transforming growth factor beta (TGF-β) is able to induce forkhead box P3 expression in naïve CD4+ T cells, promoting T-regs’ differentiation [46], and to increase the production of the anti-inflammatory cytokine IL-10 from CD4+/CD25+ T-regs [60] with potential beneficial effects in several autoimmune diseases.