DISTRIBUTION OF ANTIBODY-TITERS AGAINST PHENOLIC GLYCOLIPIDS FROM MYCOBACTERIUM-TUBERCULOSIS IN THE SERA FROM TUBERCULOSIS PATIENTS AND HEALTHY CONTROLS

Sera from tuberculosis (TB) patients and healthy controls were tested by ELISA for their antibody titres against the two major phenolic glyc olipids (PGLs) of Mycobacterium tuberculosis, PGL-tbO (a 1:3 mixture o f PGL-tb1 and its analogue whose phthiocerol moiety is phenolphthiotri ol A) and PGL-tbK. Both PGL-tbs were shown to be specific to M. tuberc ulosis, and the profiles of serum anti-PGL-tbK titres revealed that PG L-tbK, like PGL-tb1, was fairly widely distributed among strains of M, tuberculosis. Even when these two PGL-tbs were used, however, the rat e of ELISA-positives was not very high among TB patients, which is pro bably explained by the nature of the disease. Moreover, a considerable number of sera from healthy controls, especially from younger age gro ups, had high anti-PGL-tb titres, which implies that environmental exp osure to M. tuberculosis is much higher than has been estimated from t he actual TB cases. The ELISA system using these species-specific PGL- tb antigens may be useful for the survey of TB infection, since it giv es more direct information on TB infection than the PPD skin test.