ABSTRACT
Radioimmunoassay (RIA) techniques have been evaluated to detect specific tubercular antigen (TB Ag) and antitubercular antibody (TB Ab) in CSF and serum of patients with tuberculous meningitis (TBM). A solid-phase RIA using H37RV sonicate antigen of Mycobacterium tuberculosis, anti-BCG antibody, and staphylococcal protein A was standardized. TB Ag and TB Ab levels were noted to be significantly elevated in cerebrospinal fluid (CSF) as well in circulating immune complexes (CIC) isolated from serum samples of TBM patients as compared to control group (P less than 0.01). Detectability of disease by demonstrating elevated TB Ag and/or TB Ab levels in either CSF or CIC or both was 95%. There was no correlation between individual levels of TB Ag and TB Ab in CSF and in circulation. A follow-up study in patient over a period of 4-12 weeks revealed that TB antigen and/or TB Ab persisted in the majority of the cases for several weeks despite chemotherapy.