immunology of infectious and parasitic diseases - XXXVII Congress ...

HLA CLASS I AND SUSCEPTIBILITY TO CHAGAS DISEASE
CHRISTIANE MARIA AYO 1 ; CAMILA DE FREITAS OLIVEIRA 1 ; PÂMELA
GUIMARÃES REIS 1 ; EMÍLIA ÂNGELA SIPPERT 1 ; FLAVIA CARDOSO ZAGH 1 ;
MÁRCIA MACHADO DE OLIVEIRA DALÁLIO 1 ; JEANE ELIETE LAGUILA
VISENTAINER 1 ; ANA MARIA SELL 1
1 Universidade Estadual de Maringá
Introduction: Chagas‟ disease, caused by Trypanosoma cruzi, is endemic in
many countries in Latin America, affecting millions of people. It is worth noting
that uninfected individuals are found in all reported studies of endemic areas
and the variation in seropositivity is attributable to genetic factors. HLA genes
are extremely polymorphic and play a central role in the immune response
making them attractive candidates for influencing the differential outcomes of T.
cruzi. The aim of this study was to investigate allele and haplotype frequencies
of the HLA-A, B and C in seropositive chronic Chagas patients and controls in a
population from North/Northwest of Parana State, South Brazil. Methods and
Results: Peripheral blood was collected from 158 unrelated individuals (control,
95; chagasic, 63) and the DNA was extracted from leukocytes by a salting out
procedure. HLA typing was carried out according to the manufacturer's
specification for LABType SSO Typing, testing for each locus using Luminex
Technology (One Lambda, INC, USA) and the retrieved output was analyzed by
HLA Fusion software (One Lambda, INC, USA) for allele identification. The
frequencies were determined by Arlequin 3.1. software and the comparison of
allele frequencies was analyzed in 2x2 contingency tables using the chi-square
test with Yates‟ correction or Fisher‟s Test. To estimate the disease risk, odds
ratio and 95% confidence interval were calculated. Statistical analyses were
performed using the SISA statistics software. The Hardy-Weinberg equilibrium
was achieved by calculating the expected genotype frequencies and comparing
them to the observed values. Statistically significant susceptibility to Chagas‟
disease was found for HLA-B*08 allelic group (p: 0.001; OR: 7.2; 95% CI: 2.01-
25.94) and for HLA-A*02-B*14 haplotype (p: 0.001; OR: 23.9; 95% CI: 1.35-
123.8). A significant increase of the frequency of the haplotype HLA-A*02-B*35
was observed in the control group (p: 0.02; OR: 0.05; 95% CI: 0.003-0.9).
Conclusions: These results suggest that the HLA-B*08 and HLA-A*02-B*14
conferred susceptibility and HLA-A*02-B*35 conferred protection against the
development of the Chagas‟ disease, regardless of the clinical form of the
disease.
Financial support: Foundation Araucária and CAPES.