Multiple sclerosis. Cerebrospinal fluid immune complexes that bind C1q

We used a sensitive C1q-binding assay to measure levels of soluble immune complexes in 182 samples of cerebrospinal fluid (CSF) from control patients and patients with multiple sclerosis (MS). Soluble immune complexes in CSF were detected in 16% of patients with progressive MS, 38% of patients with exacerbating-remitting MS, 55% of patients with infectious or inflammatory diseases, 3% of patients with noninflammatory neurologic disorders, and in 0% of control patients with back pain. No correlations were found between the results of the C1q-binding assay and abnormalities of other CSF parameters. These included an elevated level of myelin basic protein, pleocytosis, oligoclonal bands, or an increased IgG level. Because of the lack of correlation to laboratory indexes of disease activity and the nonspecificity of a positive test, the C1q-binding assay seems to have little clinical usefulness in the diagnosis or management of patients with MS.