An enzyme-linked immunosorbent assay using adsorbed mycobacterial sonicates for the serodiagnosis of tuberculosis

Sera from 123 patients with confirmed tuberculosis and 576 patients with other non-mycobacterial diseases were tested for antibodies to an adsorbed mycobacterial sonicate antigen employing an enzyme-linked immunosorbent assay. The results show significant differences in IgG levels between sera from tuberculosis patients and controls. The results of delayed hypersensitivity skin-test reactions to purified protein derivative in both the patient and control groups were unrelated to antibody levels. The assay was able to detect antibodies for at least 4 months after diagnosis and treatment. Patients diagnosed as having tuberculosis 7 months or more before being tested did not demonstrate increased antibody levels. The assay could be useful not only as a screening technique for diagnosing tuberculosis in an immunised population but also as a means of monitoring antituberculosis treatment.