RESUMO
1. We have studied some generic and specific aspects of the humoral immune response in 96 patients with leprosy (29 paucibacillary and 67 multibacillary individuals). We determined serum immunoglobulins (IgM, IgG and IgA), CH50, C1q, C3 and C4, circulating immune complexes (CIC), C-reactive protein (CRP), rheumatoid factor (RF) and antinuclear antibodies. No specific pattern of general humoral immune changes could be observed. 2. The specific immune response was studied by the detection of specific IgM anti-M. leprae antibodies. An immunoradiometric assay (IRMA) and an ELISA were compared for clinical effectiveness. IRMA showed greater sensitivity for the serodiagnosis of leprosy as compared to ELISA (88.1 percent vs 58.2 percent for multibacillary patients and 20.7 percent vs 10.3 percent for paucibacillary leprosy patients). Specificity was 96 percent for IRMA and 97 percent for ELISA. 3. Our results indicate that nonspecific changes in the humoral immune response are of little value in assessing leprosy patients and that immune assays for the detection of specific anti-M. leprae antibodies may be of value in the diagnosis, study and follow-up of these patients