Serodiagnosis of tuberculosis by radioimmunoassay.

Mycobacteria antigens derived from whole cells and cell walls of M. tuberculosis and M. bovis (BCG) and soluble purified protein derivative (PPD) prepared from M. tuberculosis were used in solid phase radioimmunoassays to measure the amount of reactive IgG antibody in serums from 54 patients with active (culture-positive) tuberculosis (Group I), 6 patients with inactive (culture-negative) tuberculosis (Group II), 15 healthy subjects who were skin test positive to PPD (Group III), and 30 healthy persons who were PPD skin test negative (Group IV). Patients with active tuberculosis had statistically larger (p less than 0.001) amounts of IgG antibody to M. tuberculosis whole cells, cell walls, and PPD and to BCG whole cells and cell walls when compared with the amount of antibody in serums from healthy subjects who were PPD skin test negative. However, no significant differences were detected in the mean antibody response or frequency of positive antibody responses between patients with active disease and those in clinical remission. Moreover, significant amounts of antibody were detected in 7 to 20% of healthy, tuberculin-reactive subjects. On the basis of these results, it is unlikely that antibody assays alone will prove useful in the diagnosis of this disease.