[Usefulness anti-PPD antibody in the medical practice of tuberculosis]

The decline rate of tuberculosis has decreased recently in Japan. One of the problems is the tendency of increasing doctor's delay in the diagnosis of tuberculosis. One of measures against this problem is to develop a new laboratory diagnostic method. We studied anti-PPD (Purified Protein Derivative of tuberculin) antibody in serum, pleural effusion, and bronchoalveolar lavage fluid (BAL), and found its clinical usefulness in the medical practice of tuberculosis. Firstly the methods of enzyme linked immunosorbent assay (ELISA) for the antibody to PPD were examined. The expression of antibody titer in optical density was found to be the most accurate and most simple method, and was applied in this study. IgG, IgM and IgA antibody to PPD were measured in serum, BAL and pleural effusion obtained from 122 patients with pulmonary tuberculosis, 54 patients with tuberculous pleurisy, 39 patients with lung cancer, 39 patients with malignant pleurisy, 37 patients with pneumonia, 26 patients with chronic bronchitis, 51 patients with sarcoidosis, or 49 control subjects. Serum level of IgG, IgM, and IgA antibody to PPD was elevated in tuberculosis compared with those in other diseases or control subjects. The difference was most distinctive in IgG antibody. Serum IgG antibody was higher in chronic case than in acute case and IgM antibody was higher in acute case than in chronic case. IgG, IgM and IgA antibody in pleural effusion was elevated in tuberculous pleurisy compared with those in malignant pleurisy. IgG antibody was higher in chronic tuberculous pleurisy than in acute tuberculous pleurisy and IgM antibody was higher in acute pleurisy than in chronic one.(ABSTRACT TRUNCATED AT 250 WORDS)