Anti-PGL-1 antibody levels in Thai leprosy patients

Phenolic glycolipid - 1 (PGL-1) is a Mycobacterium leprae specific cell wall component. It is an immunodominant antigen and can induce a strong humoral immune response. IgM antibody levels against PGL-1 were measured in Thai leprosy patients between October 1992-April 1994 by a commercially available M. leprae particle agglutination test (MLPA). The percentage of seropositivity was much higher in newly untreated multibacillary (MB) patients (83.9%) than in paucibacillary (PB) patients (17.8%). Antibody levels in the MB group varied in the range 32-8,192, whereas they varied in the range 32-256 in the PB group. Patients being treated with multidrug therapy (MDT) were 68.3% and 19.4% seropositive in the MB and PB groups, respectively. Seropositivities in control serum specimens were 11.3% in active pulmonary tuberculosis patients, 2.6% in dermatologic patients and 4.4% in a healthy population. In conclusion, the anti-PGL-1 assay using MLPA appears to be a sensitive and specific diagnostic tool for the diagnosis of MB patients. Additionally, it may provide an alternative to the BI determination in monitoring MB patients under MDT, and also in the surveillance of such patients after MDT.