Influence of the HLA class II polymorphism in chronic Chagas' disease

Chagas' disease or American trypanosomiasis due to Trypanosoma cruzi has ex isted at least since the time of the Inca empire and contributes significan tly to cardiovascular morbidity and mortality in several countries of this continent. Due to the fundamental role of human class II molecules polymorp hic residues in the control of the immune response, a study was designed to define by DNA typing HLA class II alleles in a sample of 67 serologically positive individuals with and without cardiomyopathy and in 156 healthy con trols of similar ethnic origin. Genomic DNA extraction, PCR amplification o f the HLA-DRB1 and DQB1 second exon regions and hybridization to labelled s pecific probes were carried outfollowing the 11th International Histocompat ibility Workshop reference protocol. Comparison of DRB1 and DQB1 allele fre quencies among the patients and control subjects showed a decreased frequen cy of DRB1*14 and DeB1*0303 in the patients, suggesting independent protect ive effects to the chronic infection in this population. Allele frequencies comparison between patients with and without cardiomyopathy showed a highe r frequency of DRB1*01, DRB1*08 and DQB1*0501 and a decreased frequency of DRB1*1501 in the patients with arrhitmia and congestive heart failure. The results suggest that HLA Class II genes may be associated with the developm ent of a chronic infection and with heart damage in Chagas' disease.