Affinity immunoblotting: rapid and sensitive detection of oligoclonal IgG, IgA and IgM in unconcentrated CSF by agarose isoelectric focusing.

Two methods for the investigation of oligoclonal immunoglobulin bands in cerebrospinal fluid are compared. Isoelectric focusing (IEF) in agarose gels combined with a highly sensitive affinity immunoblotting proved to be superior to PAGE-IEF and silver staining regarding detection sensitivity and expenditure of labour. The procedure presented here allows examination of oligoclonal bands not only of IgG, but also of IgA and IgM antibodies in less than 4 h. Oligoclonal IgM bands could be detected in 6 patients with neuroborreliosis or neurosyphilis as well as in one patient with a peripheral neuropathy where other electrophoretic methods, including immunoelectrophoresis, were negative. Oligoclonal IgA bands were demonstrated only in 2 patients with a bacterial infection of the CNS. In patients with multiple sclerosis amounts of IgM and IgA in the CSF were too low to allow investigation of oligoclonal IgM or IgA bands.