Comparison of in vitro demyelination and cytotoxicity of humoral factors in multiple sclerosis and other neurological diseases.

The distribution and nature of serum factors causing in vitro demyelination and glial lysis were investigated in multiple sclerosis (MS), other neurological diseases (OND), ill control and control groups. MS sera were unique in affecting only CNS myelin and glia whereas stroke and Guillain-Barré syndrome (GBS) sera brought changes to both CNS and PNS tissue. Through both visual scoring of myelin damage and the quantitative measurement of radiolabel release from cerebellar cultures, it was evident that the MS and OND groups have similar myelino- and cytotoxic effects. This may reflect MS and OND sera sharing similar humoral factors. 74% MS, 68% OND and 22% of control scores were above a score threshold designed to exclude culture handling trauma effects. When classified by their current disease state MS patients with severe and mild disease yielded higher in vitro scores than did those with moderate disease who comprised an older age group. No other clinical features of MS patients gave any association with in vitro serum effects. The rare demonstration of bound Fab IgG in cultures after MS serum tests indicates that immune mechanisms are unlikely to make a large contribution to serum-induced demyelination and cellular change in vitro.