Anti-PGL-1 IgM isotype has been used in searching for infection, but not necessarily for the disease, because detectable IgM levels can be found in both infection and disease, although it has been demonstrated that there is a good correlation between the IgM antibody and bacillary load [24], what could explain the levels of IgM to be higher in multibacillary compared to paucibacillary. This evidence concerns the gene CD40LG and infection.