Serological response in leprosy and tuberculosis patients to the 18-kDa antigen of Mycobacterium leprae and antigen 85B of Mycobacterium bovis BCG.

Two enzyme-linked immunosorbent assays (ELISAs) for the detection of leprosy antibodies were developed. These assays were based on the recombinant 18-kDa protein of Mycobacterium leprae and the 85B antigen of M. bovis. Sera from leprosy and tuberculosis patients were analyzed, and a phenolic glycolipid-I (PGL-I) ELISA was used as a reference test. The 18-kDa ELISA reached a sensitivity of 70% on lepromatous leprosy sera. The corresponding results for the 85B and the PGL-I ELISAs were 93% and 96%, respectively. The sensitivity on tuberculoid leprosy sera was 72% for the 18-kDa antigen, 95% for the 85B antigen, and 60% for the PGL-I antigen. The 18-kDa antigen ELISA was found to have crossreactivity to sera from patients with tuberculosis, while the 85B and PGL-I assays had high specificity.