CD4 and autoimmune disease: MS is a cell-mediated autoimmune disease directed against CNS myelin antigens involving CD8+ and CD4+ cells. There is an enhancing or secondary role for Autoantibodies. The body of normal individuals possesses Autoreactive T cells against myelin elements, and it does not develop the disease in these individuals. It even could provide protective properties for the brain. With the induction of pathogenic Th17- and Th1-type and CD8 myelin autoreactive T cells, MS is developed.