Development of an enzyme-linked immunosorbent assay using arabinomannan from Mycobacterium smegmatis: a potentially useful screening test for the diagnosis of incubating leprosy.

A carbohydrate antigen composed predominantly of arabinomannan has been purified from Mycobacterium smegmatis and used in an enzyme-linked immunosorbent assay to detect anti-mycobacterial antibodies in human sera. Sera from 117 controls, 25 tuberculosis patients, 124 leprosy patients and 256 household contacts of leprosy patients were tested. When compared with the control group, 56% of tuberculosis patients, 27% of patients with tuberculoid leprosy, 77% of borderline leprosy cases, and 95% of patients with lepromatous leprosy had elevated titers. Nine percent of the household contact group had abnormally high levels of antibody. The relevance of these findings to the serodiagnosis of incubating leprosy and the management of household contacts of leprosy patients is discussed.