Genetic influence on natural cytotoxicity and interferon production in multiple sclerosis studies in monozygotic discordant twins.

A dysfunction in natural killer (NK) cell activity has been assumed to play a substantial role in the pathogenesis of multiple sclerosis (MS). To investigate whether such a defect is genetically determined and thus in combination with a certain HLA status may represent an additional risk factor for contracting MS, spontaneous and interferon (IFN) induced NK cells activity against the K562 target cell were analyzed in nine pairs of monozygotic twins discordant for MS. In addition, IFN production was tested in nonadherent lymphocytes stimulated with PHA, influenza virus or leukemia cells. When compared to healthy controls, NK function appeared to be normal in healthy twins, whereas some MS patient displayed decreased activity. No difference in IFN induced NK cell activity and IFN production could be detected between normal controls, healthy twins, and MS patients. These data argue against a genetically determined dysfunction within the NK-IFN system in patients with MS.