Characterization of antibody activity in oligoclonal immunoglobulin G synthesized within the central nervous system in a patient with tuberculous meningitis.

Thin-layer polyacrylamide gel isoelectric focusing of cerebrospinal fluid (CSF) and serum obtained from one patient 48 and 65 days after the onset of tuberculous meningitis revealed five oligoclonal immunoglobulin zones in CSF without any counterpart in serum, indicating local immunoglobulin production. Subsequent immunofixation with specific antisera revealed that three of the zones consisted of immunoglobulin G lambda present simultaneously. Immunofixation with Mycobacterium tuberculosis and bacillus Calmette-Guérin (BCG) as antigens and autoradiography revealed zones of specific antibodies in the CSF which, regarding mobility, corresponded to oligoclonal and polyclonal CSF immunoglobulin G zones. No antibody activity was detectable in the corresponding serum, indicating that the antibodies present in CSF were synthesized within the central nervous system. In seven control patients (three with multiple sclerosis, four with chronic inflammatory central nervous system diseases of unknown cause) with oligoclonal CSF immunoglobulin, no evidence for local production of antibodies against M. tuberculosis or BCG was detectable. Immunofixation with M. tuberculosis or BCG as antigens and autoradiography may prove to be a useful diagnostic complement to conventional techniques in patients with suspected tuberculous meningitis.