Evaluation of Serodiagnosis Detecting IgG Antibodies Against Purified Protein Derivative and Alpha Antigen in Patients with Active Pulmonary Tuberculosis by Enzyme-Linked Immunosorbent Assay

Detection of IgG antibodies against purified protein derivative (PPD) prepared from Mycobacterium tuberculosis strain Aoyama B and alpha antigen, a homogeneous protein prepared from M. tuberculosis strain H37Rv by immunosorbent affinity chromatography, was done by a method of enzyme—linked immunosorbent assay (ELISA) and its diagnostic usefulness was also evaluated in this study. Sera from 80 patients with active pulmonary tuberculosis, 25 patients with inactive tuberculosis, 200 healthy adults, 117 healthy children, 84 patients with diseases other than tuberculosis and seven patients due to atypical mycobacteria were examined. The titer of each test serum was calculated by a computer system using the standard curve obtained by serial dilution of a standard serum. Use of phosphate buffer saline (PBS) with gelatin as blocking buffer in ELISA showed considerably useful results than the use of PBS with bovine serum albumin.