The detection by immunoassay of antibody to mycobacterial antigens and mycobacterial antigens in bronchoalveolar lavage fluid from patients with tuberculosis and control subjects.

Bronchoalveolar lavage (BAL) samples from patients with pulmonary tuberculosis and from control subjects were studied using direct and inhibition enzyme-linked immunosorbent assay (ELISA) for the detection of IgG and IgA antibody to Mycobacterium tuberculosis culture filtrate and purified antigen 5 and for the detection of mycobacterial antigens. The IgG and IgA antibodies were found in the majority of samples from tuberculous patients. The IgG titers were higher than were IgA titers. Substantial nonspecificity was observed for antibodies to crude M tuberculosis culture filtrate. Antibodies to purified M tuberculosis antigen 5 were more specific. The detection of antibody in BAL did not offer advantages over previously described serodiagnostic assays. Antigen was found in some BAL samples from tuberculous patients. Greater specificity was observed with an assay based on purified antigen 5 than on crude mycobacterial culture filtrate.