Serodiagnosis of tuberculosis: detection of mycobacterial antibodies and antigens.

SETTING

The diagnosis of tuberculosis is based primarily on identification of mycobacteria and on clinical evidence. Recently, serological studies have been widely used experimentally as a diagnostic approach.

OBJECTIVE

The aim of our study was to optimize serodiagnosis of tuberculosis by detecting mycobacterial antigens and antibodies in sera from patients with lung tuberculosis, non-related diseases and healthy controls.

DESIGN

Mycobacterium tuberculosis H37Rv was disintegrated by pressure. Cell walls were extracted with 3 M KCL and were subjected to gel filtration in Toyopearl gel. Immune sera were prepared by immunization of rabbits with cell wall material. Anti H37Rv antibodies were purified by affinity chromatography. The reagents obtained were used to detect serum antibodies and antigens (following immune complex dissociation) using ELISA.

RESULTS

Using fraction 6 of cell wall extract, antibodies were detected in 72.2% of TB patients; there were no positive reactions in control subjects. By use of affinity-purified antibodies, antigens were detected in 77.1% of TB patients, 10% of patients with unrelated diseases and 6.7% of healthy controls.

CONCLUSION

Effective serodiagnosis of tuberculosis can be achieved only by combining detection of both circulating antibodies and antigens using highly specific purified reagents and immune complex-dissociated sera.