The red blood transfusion is a practice often used in patients with haematological and oncological diseases. However, the investigation of human leucocyte antigen (HLA) system frequency in these individuals is of great importance because multiple transfusions may lead to HLA alloimmunization. Brazil is a country that was colonized by many other ethnicities, leading to a mixed ethnicity and regionalized population. In view of the importance of HLA typing in these patients, the aim of this study was to investigate the allele and haplotype frequencies from polytransfused patients from three different regions from Brazil. HLA-A, HLA-B, HLA-C, HLA-DRB1 and HLA-DQB1 genotyping of 366 patients was performed by PCR-SSO, based on the Luminex technology (One Lambda(®) ), and the anti-HLA class I and class II antibodies were analysed using LabScreen Single Antigen Antibody Detection (One Lambda, Inc.). Allele and haplotype frequencies of polytransfused patients of three regions from Brazil were obtained using the Arlequin program. The most frequent allele frequencies observed were HLA-A*02, A*03, B*15, B*35, B*51, C*07, C*04, C*03, DRB1*13, DRB1*11, DRB1*07, DRB1*03, DRB1*01, DQB1*03, DQB1*02, DQB1*06 and DQB1*05. There were differences between the groups for allele variants HLA-B*57 (between Group 1 and Group 2) and HLA-C*12 (between Group 1 and Group 3). The most frequent haplotypes found in the sample were HLA-A*01B*08DRB1*03, DRBI*07DQB1*02, DRB1*01DQB1*05, DRB1*13DQB1*06 and A*02B*35. HLA class I and II antibodies were detected in 77.9% and 63.9% patients, respectively, while the both alloantibodies were detected in 62 (50.9%) patients. In conclusion, the HLA typing for polytransfused patients in each region has a great importance, as seen in this study; individuals from different regions from Brazil have HLA distribution not completely homogeneous.

Aim:The red blood transfusion is a practice often used in patients with hematological and oncological diseases. However, the investigation of HLA system frequency in polytransfused patients is of great importance because multiple transfusions may lead to HLA alloimmunization, causing many complications and limitations for these patients especially in cases requiring organ or bone marrow transplantation. In view of the importance of HLA typing in these patients, the aim of this study was to investigate the allelic and haplotype frequencies from polytransfused patients from three different regions of Brazil.Methods: Were analyzed HLA-A, -B, -C, -DRB1, -DQA1 and -DQB1 gene frequencies from 366 polytransfused patients of different regions from Brazil, which was divided onto three groups according to the region and ethnic (Group 1: Mixed population from the north of Paraná State (n = 93), Group 2: Mixed population from the southeast of São Paulo State (n = 96) and Group 3: Afro-Brazilian from the northeast of Brazil (n = 177). The genotyping was analyzed by PCR-SSO, based on the Luminex technology (One Lambda Ò , CA, USA). Allelic and haplotypic frequencies of polytransfused patients for the three groups were performed using the Arlequin program.Results: The most frequently allele frequencies observed were HLA-A ⁄ 02, A ⁄ 03, HLA-B ⁄ 15, B ⁄ 35, B ⁄ 51, HLA-C ⁄ 07, C ⁄ 04, C ⁄ 03, DRB1 ⁄ 13, DRB1 ⁄ 11, DRB1 ⁄ 07, DRB1 ⁄ 03, DRB1 ⁄ 01, HLA-DQB1 ⁄ 03, DQB1 02, DQB1 ⁄ 06 and DQB1 ⁄ 05 in all the three groups. When evaluating the differences between the groups for allelic variants, HLA-B ⁄ 57 (between group 1 and 2) and HLA-C ⁄ 12 (between group 1 and 3) were statistically different. The most frequently haplotypes found in the subjects were HLA-A ⁄ 01B ⁄ 08DRB1 ⁄ 03, DRBI ⁄ 07DQB1 ⁄ 02, DRB1 ⁄ 01DQB1 ⁄ 05, DRB1 ⁄ 13DQB1 ⁄ 06 and A ⁄ 02B ⁄ 35.Conclusion: The HLA typing for polytransfused patients in each region has a great importance, as seen in this study; individuals from different regions from Brazil have HLA distribution not completely homogeneous.The insertion of a genotyping program for these patients would assist in the reduction of alloimmunization against HLA system in red blood transfusion with no leuko-depletion, thus avoiding further complications.

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