Detection and isolation of immune complexes in multiple sclerosis cerebrospinal fluid

Immune complexes were studied in the cerebrospinal fluid (CSF) of 20 multiple sclerosis (MS) and 20 other neurological disease (OND) patients using polyethylene glycol precipitation; ten samples from each group were also examined using gel chromatography followed by ELISA. Polyethylene glycol detected predominantly IgG and IgM complexes in 13 of 20 MS samples and four of 20 OND samples. Intact MS complexes ranged in size from 230 to 340 kDa and contained 64 and 53 kDa antigens. Gel chromatography detected IgA complexes in eight of ten MS samples and one of ten OND samples; these complexes appeared to consist of polymeric IgA rather than true antigen. Chromatography detected IgG complexes in nine of ten MS and four of ten OND samples. Intact MS complexes ranged from 240 to 320 kDa and contained 200 and 150 kDa antigens. This study suggests that immune complexes are a very frequent finding in the CSF of MS patients and are in sufficient quantity to visualize on gel electrophoresis.