Phenolic glycolipid-1 (PGL-I) antigen is the main antigenic glycolipid of Mycobacterium leprae producing antibodies of the IgG (immunoglobulin type G) and IgM (immunoglobulin type M) classes, related to disease activity and clinical form.8, 9 The detection of IgM antibodies to phenolic glycolipid I (PGL-I) in serodiagnosis is the best standardized test for leprosy. This evidence concerns the gene CD40LG and leprosy.