Combination ELISAs for antiviral antibodies in CSF and serum in patients with neurological symptoms and in healthy controls.

A combination enzyme-linked immunosorbent assay (ELISA) was designed to improve the estimation of serum: cerebrospinal fluid (CSF) antiviral IgG ratios. Microplate wells were coated with five different virus antigens. Serum and CSF from 66 patients referred for CSF serology and from 21 healthy controls were studied. In a comparison with serum: CSF IgG titre ratios, absorbance ratios were found to be suitable for the evaluation of intrathecal antiviral IgG synthesis. A slight blood-brain barrier (BBB) disturbance affected only the passage of albumin over the BBB, whereas a more pronounced BBB defect resulted in increased IgG levels in the CSF. Intrathecal antiviral IgG synthesis was demonstrated in 15 patients with viral CNS infections or inflammatory diseases. Very high serum: CSF antiviral IgG titre ratios and absorbance ratios, found in six patients, were interpreted as signs of diminished IgG passage over the BBB due to impaired CSF circulation.