Detection of M. leprae-specific antigens with dot-ELISA in urine and nasal samples from leprosy patients.

One-hundred-two urine and nasal samples collected from leprosy patients of different classifications of disease were studied for the presence of Mycobacterium leprae antigens, including phenolic glycolipid-I (PGL-I). Lipids were extracted from the urine samples, and nasal washings were concentrated and used as such in the dot-ELISA. Two types of primary antibodies, a polyclonal antibody obtained from lepromatous (LL) leprosy patients' pooled and absorbed sera and an anti-PGL-I monoclonal antibody, were used for the detection of M. leprae antigens from these samples. The polyclonal sera detected 23% to 36% of the paucibacillary (PB) and 100% of the multibacillary (MB) leprosy cases from the urine samples. Corresponding values for nasal detection were 10% to 18% for PB and 100% for MB cases. The monoclonal antibody against PGL-I could not detect tuberculoid (TT) leprosy cases. From the urine samples, however, 16% of the borderline tuberculoid (BT), 25% of the borderline (BB), 80% of the borderline lepromatous (BL), and 100% of the LL leprosy cases were detectable. It was interesting to note that PB, skin-smear negative cases were detectable from urine examination. The specificity and sensitivity of the test is discussed in relation to the crossreacting antigens.