Levels of antibody to defined antigens of Mycobacterium tuberculosis in tuberculous meningitis

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Abstract
The aim of the study was to develop an antibody immunoassay for tuberculous meningitis with a sensitivity greater than that of the initial bacterial smear while maintaining a 100% specificity. Antibody titers to five purified antigens of Mycobacterium tuberculosis were measured in cerebrospinal fluid by using an enzyme-linked immunosorbent assay technique. Seventy-four patients with tuberculous meningitis (26 culture positive) were compared with 26 patients with purulent meningitis, 69 patients with suspected but excluded tuberculous meningitis, and 29 patients with other neurological diseases. Antibody responses to both the 14-kilodalton (kDa) antigen and lipoarabinomannan were immunodominant, accounting for 74% of those with any antibody titer to a soluble extract of M. tuberculosis. A sensitivity of 61% was achieved (77% for the culture-positive samples) by using immunoglobulin G titers to lipoarabinomannan and the 14-, 19-, and 38-kDa antigens. Thus, estimation of levels of antibody in cerebrospinal fluid to selected mycobacterial antigens would be valuable in the diagnosis of tuberculous meningitis. The possible reasons for the immunodominance of the 14-kDa antigen and lipoarabinomannan in the pathogenesis of tuberculous meningitis are discussed.