Early abnormalities of the antibody response against Mycobacterium tuberculosis in human immunodeficiency virus infection

Among human immunodeficiency virus (HIV)-infected persons, those who react against purified protein derivative (PPD) have higher risk of tuberculosis. Since PPD testing has limited predictive power in HIV-positive populations, new markers of antituberculous immunity were sought by analyzing antibodies to Mycobacterium tuberculosis antigens (PPD and its fraction A60) in 102 HIV-positive subjects, some PPD-positive and some PPD-negative, and in 23 HIV-positive tuberculosis patients. ELISA and Western blotting were used. Forty HIV-negative healthy subjects and 40 HIV-negative tuberculosis patients were evaluated as controls. While all those HIV-negative and PPD-positive had IgG antibodies recognizing the 38-, 28-, and 19-kDa M. tuberculosis antigens, only 26% of those HIV-positive and PPD-positive (all with < 400 CD4+ cells/mm3) and none of the HIV-positive tuberculosis patients recognized them, indicating that the lack of IgG against those antigens, in the presence of a specific IgM response, is a marker of immunodeficiency.