Most Mycobacterium leprae carbohydrate-reactive monoclonal antibodies are directed to lipoarabinomannan

Each of more than 30 monoclonal antibodies that had been raised against Mycobacterium leprae and previously classified as reactive with carbohydrate was shown to be directed against lipoarabinomannan, a prominent, highly pervasive, myo-inositol-phosphate-containing, cross-reactive antigen within the leprosy bacillus. Some of the antibodies preferentially bound to the lipopolysaccharide of M. leprae rather than to that of Mycobacterium tuberculosis, suggesting the presence of distinguishing structural features. The presence of alkali-labile inositol 1-phosphate in the lipopolysaccharide from M. tuberculosis and its apparent absence from the M. leprae product may account for the difference.