Immunopathogenesis of multiple sclerosis is a complex process involving T cell mediated autoimmunity at initial stage of disease. A long standing view that Th1 cells are critical for early inflammatory development of lesions is challenging by recent findings that Th1 helper cells with Th17 phenotype are even more important. A complex autoimmunity of MS is further complicated with evidence that CD8 cells, regulatory T cells, clonal expansion of B cells, cells of myelin lineage, antibodies and complement, as well as process intrinsic to central nervous system contribute to the tissue destruction. Although there are a lot of evidences about inflammatory phase of MS, far less is known about mechanisms involved in degenerative phase of disease. It is not known weather quantitative, or qualitative differences in inflammatory response contributes to destruction of the tissue, or as it was shown experimentally demyelination may sometimes occur independent of T cells.

Understanding of immunopathogenesis of MS especially regarding various stages of disease is necessary for clinicians in choosing optimal therapy of MS in individual patients. Influences of immunomodulatory treatment on various stages of MS immuno-pathogenesis are presented.