Reduced anti-Mycobacterium tuberculosis antibody response in tuberculosis patients with acquired immunodeficiency syndrome.

1. When the sera of patients with tuberculosis were tested for anti-Mycobacterium tuberculosis IgG using an indirect ELISA, the test was positive for 94.1% of the samples from patients not having AIDS (N = 51), but for only 37.5% of the samples from patients with AIDS (N = 16). 2. False-positive results were obtained for 7.3% of patients not infected with HIV (N = 96) and for 4.7% of patients infected with HIV (N = 64). 3. In most serum samples obtained from patients with tuberculosis and AIDS after the beginning of specific treatment there was a reduction of the ELISA absorbance at 490 nm with time. 4. These results indicate that serological tests for the detection of anti-M. tuberculosis IgG in patients with AIDS are of limited value for the diagnosis of tuberculosis, most likely as a consequence of the underlying immune defect of the patients.