Third complement component in cerebrospinal fluid in neuro-Behçet's syndrome. Conversion patterns by crossed...

Thirteen cerebrospinal fluid specimens (CSFs) from 10 patients with neuro-Behçet's syndrome (nB) were examined for the presence of conversion products of C3 protein by means of crossed immunoelectrophoresis. C3 conversion products were found in 4 CSFs from nB patients, and the proportions of the split products to the total immunoprecipitate zones were 17, 34, 61 and 63%, respectively. CSFs with C3 conversion patterns showed higher C3 protein (beta 1C/A) levels compared with those with non-conversion, whereas the differences of C4 protein (beta 1E) levels were unremarkable. CSF with C3 conversion patterns also showed apparent inflammatory characteristics indicating blood-CSF barrier involvement which would be deduced from increased alpha 2-macroglobulin and IgA, both being regarded as sensitive internal barrier parameters: but IgA measurement was much higher than usually expected values. It is suggested that the increase in CSF C3 might be initiated by accelerated consumption of complement through the alternative pathway, leading to hypersynthetic or hyperinflux response in CSF.