FIG. 2.
Levels of anti-M. tuberculosis IgG antibodies in serum from untreated patients with pulmonary TB and patients with other pulmonary diseases. The level of antibody to Ag 360 is given on the y axis, expressed as the A450 (high values were converted from A630 results; see Materials and Methods). Closed circles represent individual TB patients, and open circles represent negative controls. Horizontal bars represent the median antibody levels in the groups; vertical error bars show the interquartile range. Antibody levels in untreated TB patients were significantly higher than those in patients with other pulmonary diseases (P = 0.02).