Serological activity of a characteristic phenolic glycolipid from Mycobacterium leprae in sera from patients with leprosy and tuberculosis

Serological activity against a purified phenolic glycolipid from Mycobacterium leprae, which may be obtained in large amounts from M. leprae infected armadillo liver, was investigated using immunodiffusion and an enzyme linked immunosorbent assay (ELISA). Generally a good correlation was obtained between these techniques, but the ELISA was more sensitive and convenient. Relatively high IgG and IgM anti-glycolipid antibody levels were found in lepromatous leprosy patients. The antibody titres to the glycolipid were, however, low when compared with antibody titres to crude sonicates. Since the glycolipid is present in large quantities, this suggests that it is not very immunogenic. Antibody against the glycolipid especially of the IgM class, was demonstrable in some tuberculoid leprosy patients, although at much lower titres than in the lepromatous leprosy sera. In lepromatous leprosy patients that were skin smear negative after more than 5 years of treatment the IgG anti-M. leprae derived glycolipid activity had decreased markedly. The anti-IgG and IgM glycolipid antibody levels in tuberculosis patients did not differ significantly from the levels in appropriate normal healthy subjects. The glycolipid antibody levels in patients infected with M. kansasii, M. avium or M. intracellulare also fell within the range of normal healthy individuals.