HLA and susceptibility to leprosy.

This review examines the evidence for involvement of MHC-associated factors in host immune response to Mycobacterium leprae, by collating HLA studies of sporadic and familial leprosy and discussing possible HLA-related immunological mechanisms in determining host response. Formal linkage analysis of 109 multiple-case families with data available for HLA haplotype segregation showed that under a three-allele recessive model for susceptibility to leprosy, linkage was observed between the HLA complex and a leprosy susceptibility locus at a recombination fraction of 20%. The significance of the linkage relationship was confined to families with at least two tuberculoid leprosy offspring and neither parent affected. When one parent was affected, with leprosy of any clinical type, lod scores could neither implicate nor exclude linkage between HLA and leprosy susceptibility and this apparent paradox can be explained by the presence of an additional, non-HLA linked susceptibility locus for leprosy.