ANALYSIS OF THE MAJOR ANTIGENIC DETERMINANTS OF THE CHARACTERISTIC PHENOLIC GLYCOLIPID FROM MYCOBACTERIUM-LEPRAE

Abstract

Antibodies to the major phenolic glycolipid purified from M. leprae were demonstrated previously in sera of leprosy but not tuberculosis patients using an ELISA [enzyme-linked immunosorbent assay]. The major antigenic determinants on this molecule were investigated using antisera raised in rabbits to the purified glycolipid and with a pool of sera from human lepromatous leprosy patients. A small, but significant cross-reaction is observed with the glycolipids from M. bovis and M. kansasii, which contain the phenolphthiocerol dimycocerosate part of the molecule but have different sugars, and also with a semi-synthetic attenuation indicator lipid, which shares the phenolphthiocerol but has no sugars. There was however no cross-reaction with phthiocerol dimycocerosate. The disaccharide, corresponding to the 2 terminal sugars of the M. leprae glycolipid was chemically synthesized and shown to inhibit the reaction between glycolipid and antibody in the ELISA. The cross-reactivity observed with the M. bovis and M. kansasii glycolipids was not inhibited by the synthetic disaccharide. The cross-reactivity is probably associated with the phenol ring and the disaccharide may be a unique antigenic determinant of M. leprae.