Evaluation of the potential role of enzyme-linked immunosorbent assay in serodiagnosis of tuberculosis.

The serodiagnosis of tuberculosis was evaluated by means of enzyme-linked immunosorbent assay of IgG antibody to mycobacterial antigen 60. The study population consisted of 63 patients with active tuberculosis comprising 43 pulmonary tuberculosis, 15 tuberculosis pleurisy, four miliary tuberculosis, and one tuberculous lymphadenitis. The control group consisted of 48 patients embracing 8 cases of inactive pulmonary tuberculosis, 31 cases of pulmonary disorders other than tuberculosis, and nine normal persons. There was a significant difference in antibody titers of sera between patients of active tuberculosis and control group (P < 0.001). The sensitivity of the test for active pulmonary tuberculosis was 81.4% and the specificity was 85.4% (cutoff value 300 units). The sensitivity for all active tuberculosis was 61.9%. There was positive correlation between serum titer of active pulmonary tuberculosis and the extent of disease on chest radiography (r = 0.4, P < 0.01). A positive correlation was found between the titers of pleural fluids, and the corresponding sera in 15 patients (eleven tuberculous pleurisy and four nontuberculous controls) (r = 0.85, P < 0.001). Whether serum or pleural fluid, the positive rate of the assay for tuberculous pleurisy was relatively low. In conclusion, the A60 IgG ELISA test may be useful in serodiagnosis of pulmonary tuberculosis and assessment of the disease extent, although it might not yield a high sensitivity for tuberculous pleurisy.