Résumé
1. We determined the anti-PGL1 levels of 402 individuals from the Ribeir ao Preto region since the phenolic glycolipid (PGL1) is a specific Mycobacterium leprae antigen. This group consisted of 47 leprosy patients (26 with the lepromatous form, 16 with the tuberculoid form and 5 with the borderline form), 12 tuberculosis patients, 19 leprosy contacts, and 324 healthy blood donors from the Hemocenter of the University Hospital, Faculty of Medicine of Ribeir ao Preto, University of S ao Paulo. Anti-PGL1 levels were detected by ELISA. 2. Anti-PGL1 levels were normal in patients with tuberculoid and borderline leprosy, in tuberculosis patients and in almost all of the healthy blood donors. Patients with untreated lepromatous leprosy had elevated anti-PGL1 levels while most patients under treatment (9/16) had normal anti-PGL1 levels. Only 3 per cent of blood donors (10/324) had elevated anti-PGL1 levels, but when these individuals were submitted to clinical and bacilloscopic examination no signs of disease were found. To complete the clinical investigation, these 10 subjects were submitted to the Mitsuda reaction which was negative in 3 of them. All of these 10 subjects are being monitored, since they may be at risk to develop leprosy. 3. On the basis of the present data, it seems that ELISA is a potentially important assay for the detection and chemotherapy of subclinical leprosy, permitting the control of epidemic centers of the disease