Anti-phenolic glycolipid 1 IgM antibodies in leprosy patients and in their household contacts.

Though they have no apparent protective action, the specific antibodies are important markers of the infection with Mycobacterium leprae. For their detection we employed an ELISA method using as substrate a synthetic immunodominant disaccharide of phenolic glycolipid 1 antigen of M. leprae, conjugated with bovine serum albumin (D-BSA). Increased levels of anti-D-BSA antibodies of the IgM class were detected in 61.5% of the 13 leprosy patients and in 13.3% of their 53 household contacts, whereas they were not found in any of the 37 normal blood donors. A strong correlation (r = -0.846) was found between the antibody levels and the duration of the disease among the 12 patients with lepromatous leprosy. These preliminary data demonstrate the usefulness of this method for epidemiological studies and for the detection of cases with subclinical infection.