SEROLOGICAL COMPARISON OF PURIFIED ANTIGEN-60 AND ANTIGEN-85A (P-32) OF MYCOBACTERIUM-BOVIS BCG, AND PURIFIED PROTEIN DERIVATIVE, IN ACTIVEPULMONARY TUBERCULOSIS

The immunoglobulin G (IgG) response directed against Mycobacterium bov is BCG antigens 60 (A60) and 85A (P32), and purified protein derivativ e (PPD), was investigated in order to compare the serodiagnostic poten tials of these antigens in tuberculosis (TB). The sera of 59 patients with active minimal or moderately advanced pulmonary TB and of 59 heal thy control subjects were tested by enzyme-linked immunosorbent assay. The frequencies of positivity were significantly higher (P < 0.001) i n patients than in controls and similar with all three antigens. The s trongest correlation was found between the responses to A60 and PPD (P < 0.001), the weakest between the responses to A60 and P32 (P < 0.05) . Discrepancies were observed in newly diagnosed patients before the i nstitution of specific chemotherapy and in patients with negative dire ct smears at the time of diagnosis. Untreated patients with negative d irect smears presented the lowest sensitivities. P32 was the most effe ctive antigen in diagnosing these cases (50% positivity); A60 was not better than PPD (29% and 21% positivity, respectively). The results pr esented here emphasize the importance of comparing antigens with the s ame samples in order to allow their real respective evaluation.