Diversidade de alelos e haplótipos HLA-A, -B e -DRB1 em uma amostra de candidatos a transplante renal no Brasil

Abstract

Introduction: The HLA (Human Leukocyte Antigen) molecules are proteins encoded by genes highly polymorphic and are involved in the immune response process. Polymorphisms of HLA genes differ between populations, both in frequency and in the presence or absence of specific alleles and haplotypes. Considering that the distribution of organs for transplant depends on HLA matching between donor and recipient, the knowledge and determination of the HLA polymorphism are of great importance in the process of allocation of organs for transplantation. Moreover, the knowledge of the HLA diversity is an important tool for studies of the origin of populations. Objectives: This study aimed to characterize the allele and haplotype frequencies of HLA-A, -B, and -DRB1 in a cohort of renal transplant candidates populations in the region of São José do Rio Preto (State of São Paulo), to compare the allele frequencies between Caucasian and Black in that region, as well as to compare these frequencies with different Brazilian populations reported. Materials and Methods: The HLA-A, -B, and -DRB1 allele and haplotypes frequencies were analyzed in a sample of 2.624 individuals and classified according to the ethnic group (2.347 Caucasians and 277 Blacks). The HLA class I (A, B) and class II (DRB1) specificities were determined by Complement-Dependent Microlymphocytotoxic (CDC) and Polymerase Chain Reaction/Sequence Specific Priming (PCR-SSP) methods, respectively. Results: All loci studied were in Hardy–Weinberg Equilibrium (p>0.05). Twenty-one HLA-A, 34 HLA-B and 13 HLA-DRB1 allelic groups were identified. The most frequent alleles for each locus were HLA-A*02, HLA-B*35, and HLA-DRB1*11. The most frequent haplotypes found were A*01 B*08 DRB1*03 among Caucasians and A*29 B*44 DRB1*07 among Blacks. Conclusions: The most common alleles for each locus among the renal transplant candidates were A*02, B*35 and DRB1*11. The most common haplotype was A*01 B*08 DRB1*03. The same haplotype was the most frequent in Caucasoid sample while the haplotype A*29 B*44 DRB1*07 was the most common in the Blacks sample.