The serum and cerebrospinal fluid of patients with multiple sclerosis, in presence of human complement, caused destruction of glial cells and myelin in cultured nervous tissue, particularly in the acute stage of the disease. Cytotoxicity of the cerebrospinal fluid (CSF) was not wholly specific for multiple sclerosis, being observed also in cases of encephalitis and certain viral diseases. The degree of cytotoxicity of the CSF correlated with the increase in γ-globulin (IgG) in the cerebrospinal fluid. Immunoelectrophoresis studies of the CSF showed the presence in 50% of cases of an abnormal fast γ-globulin component.
These findings have two important implications. Firstly they support the concept that demyelination in multiple sclerosis and related diseases is the result of an autoimmune process. Secondly they are useful for the laboratory diagnosis of multiple sclerosis and its differentiation from non-demyelinating disorders of the nervous system.