POLYMORPHISM OF THE DRB1 ALLELES IN ARGENTINIAN CHAGASIC PATIENTS WITH AND WITHOUT CARDIOMYOPATHY

RACCA L; GARCÍA BORRÁS S; DIEZ C; COTORRUELO C; PELLIZON O; BIONDI C; BELOSCAR J; BOTTASSO O

Madrid - España

Congreso; XVII Regional Congress of the ISBT Europe; 2007

International Society of Blood Transfusion

Background: Infection with the protozoan parasite Trypanosoma cruzi (T. cruzi) causes Chagas’ disease, a major health problem in the American continent. Chronic Chagas’ disease occurs in a variable number of infected individuals and mainly manifests as an inflammatory cardiomyopathy that may lead to a fatal course. The factors underlying the establishement of chronic myocardial lesions are not fully understood. Previous studies have suggested an influence of HLA molecules on the regulation of the anti-T. cruzi immune response and association of HLA antigens with heart damage was also found in several American countries, with findings showing a regional-related variation. The aim of the study was to investigate the contribution of the HLA-DRB1 alleles in determining the susceptibility to T. cruzi infection as well as in the development of chagasic heart disease in subjects that were born in endemic areas of Chagas´disease from Santa Fe Province, Argentina. Methods:The study included 71 unrelated individuals serologically positive for T. cruzi. All subjects presented positive reactions in both tests (ELISA and indirect haemagglutination). Cardiac involvement was established on the basis of chest X-ray and electrocardiographic abnormalities. Cases were from areas of endemic infection of Santa Fe Province, Argentina. A group of 81 no related healthy individuals with neither symptoms nor previous diagnosis of Chagas disease was studied as control group. Genomic DNA was extracted from peripheral blood and used as a template to amplify by the PCR the polymorphic second exon of the HLA-DRB1. PCR products were hybridized separately with sequence specific oligonucleotides (SSO). Differences in the distribution of HLA-DRB1* alleles between Chagas disease patients and controls were analyzed by or Pearson´s c2 test with Yates correction or Fisher´s exact test if applicable. Odds ratios and relative risks were also calculated. Results: Chronically T. cruzi-infected cases and healthy controls revealed 20 HLA-DRB1 different alleles. Among seropositives alleles occurring at higher frequencies (%) were DRB1*0409 (24.65), DRB1*1503 (13.38) and DRB1*0701 (8.45). Whit reference to controls the following alleles were the most prevalent ones recorded in them: DRB1*0701 (14.20), DRB1*1103 (12.96), DRB1*0808 (12.35), DRB1*1303 (9.26) and DRB1*1101 (8.02). Between-group comparisons only revealed significant differences for the DRB1*0409 and DRB1*1503 alleles seen in seropositives (P < 0.0001).Further analysis for the predominant gene frequencies revealed that seropositives had a respective augmented and decreased chance of presenting the alleles DRB1*0409 [OR = 26.4 (IC 95%: 6.24 -112.47), RR = 19.97 (4.89 – 67.56)] and DRB1*1503 [OR=26.49 (IC 95%: 3.28 -188.34), RR = 21.68 (2.94 – 159.91)]. When seropositives were separated according to the presence of cardiac involvement, cases with cardiomyopathy (n=38), had a greater occurrence of the DRB1*1503 allele (17/71) respect to the group without heart damage (n=33, 2/33) [OR=9.22(1.92-60.46), RR=1.87(1.47-2.37)]. Conclusions: Molecular typing allowed the identification of increased frequencies of DRB1*0409, and DRB1*1503 in infected individuals respect the seronegative controls, suggesting that these alleles could be related with the infection by T. cruzi. Increased frequency of DRB1*1503 allele was found among cardiomyopathy patients suggesting that this allele could be associated with the genetic susceptibility to cardiac damage in these individuals.