Natural antibodies in human cerebrospinal fluid to rabbit erythrocytes

With an indirect agglutination technique using rabbit antisera to human immunoglobulin, IgG antibodies to rabbit erythrocytes were detected in 211 of 221 unconcentrated cerebrospinal fluids from patients with diseases of the nervous system and controls. The titres varied from 0.25 to 128. The highest titre in the control group was 4, the geometric mean 1.5. The titres were highest in the groups with elevated total protein, for instance inflammatory diseases with mean titre of 9.25. The titre divided by total protein concentration did not vary much in the different groups, but tended to be higher than controls in multiple sclerosis, inflammatory diseases and vascular brain lesions, and lower in the other groups. It did not increase parallel to IgG in multiple sclerosis and inflammatory diseases.