Associação entre os alelos HLA-DRB1 e a aloimunização eritrocitária

• Autor(a) principal: Souza, Conceicao Pinheiro De [UNIFESP]
• Data de Publicação: 2019
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UNIFESP
• Texto Completo: https://sucupira.capes.gov.br/sucupira/public/consultas/coleta/trabalhoConclusao/viewTrabalhoConclusao.jsf?popup=true&id_trabalho=7699099; https://repositorio.unifesp.br/handle/11600/59625
• topic: Erythrocytes; Alloimmunization; Alleles; HLA-DRB1; Analysis In Silico; DRB1 Molecule; Anchor Peptide; Eritrócitos; Aloimunização; Alelos; HLA-DRB1; Análise In Silico; Molécula DRB1; Peptídeo Âncora

Background: The immunogenicity of antigens from blood group systems is now better understood by the availability of knowledge of the genetic basis of the proteins involved, molecular orientation in the erythrocyte membrane and the nature of cellular immune responses. Aims: To investigate the association of the HLA-DRB1 alleles in the selective immune response against the antigens of the RH, KEL, FY, JK and MNS systems, either in the sensitization against one or multiple erythrocyte antigens, as well as to verify if there is any allele associated with a protective effect alloimmunization. Methods: This study that analyzed blood samples from 215 patients alloimmunized against antigens from the RH, KEL, FY, JK and MNS systems and compared them with three control groups: 100 blood donors, 101 non-alloimmunized patients and 174,015 candidates for bone marrow donation. Alloantibodies were identified by gel methodology and confirmed by erythrocyte phenotyping. The HLA-DRB1 genotyping was performed by the PCR- SSO technique, using Luminex technology. The GraphPad InStat software was used for statistical analysis. The in silico analysis was performed using the NetMHCIIpan-3.2 server, able to predict the possibilities of interaction between the amino acid sequences of the RhD, RhCE, KEL, FY, JK and MNS proteins and the polymorphic pockets residues of the DRB1 molecules. Alignment was used to evaluate the similarity between the residues located along the β1 domain of the HLA-DR molecules, which showed strong interaction with the anchor peptides derived from the antigenic proteins. Results: Among the multialoimmunized patients, the anti-D+C association was the most frequent, present in 90.3% of the associations with anti-D. Statistical analysis indicated the association between the HLA-DRB1*01 allele and the anti-C and anti-Jka alloimmunizations, as well as the HLA-DRB1*15 allele in the comparison between patients with single and multiple clinically relevant red blood cell antibodies and bone marrow donors control group. This latter finding was due to the association of the HLA-DRB1*15 allele with the anti-D, -C, -E and -K aloimmunizations. The in silico analysis confirmed the associations shown, demonstrating a strong interaction between the DRB1*01 molecule and the anchor peptides derived from the RhCe and JK proteins, and between the DRB1*15 molecule and the major anchor peptides derived from RhD, RhCe, RhcE and KEL proteins, which contained the polymorphic determinants of D, C, E and K antigens in their sequences or adjacent regions. Although the HLA-DRB1*11 allele had a higher frequency among bone marrow donors, apparently exerting a protective effect on alloimmunization, in silico analysis refuted this finding. While the protein sequence containing the 193M polymorphism of the K antigen showed high histocompatibility promiscuity with numerous DRB1 molecules, the sequence containing the 280D polymorphism of the Jka antigen showed interaction only with the DRB1*01 molecule, and the sequences containing the polymorphisms of Fya (42G ) and S (29M) showed weak binding with few molecules. Conclusion: The anti-D+C association, whose frequency is high among alloimmunized patients, could be explained by two factors: the high phenotypic frequency of D and C antigens in the population and the interaction capacity of several DRB1 molecules, such as DRB1*12:01, *15:01 and *15:03, with the anchor peptides derived from the RhD and RhCe proteins, which contained 60I, 68S and 103S polymorphisms common to D and C antigens. The difference in reactivity between the DRB1 molecules and the JK, FY and MNS proteins observed in the in silico analysis seems to be directly associated with the low immunogenicity of the Jka, Fya and S antigens, compared to the D, C, E and K antigens. In silico analysis of blood group proteins may be a practical resource, at no additional cost to the laboratory, which allows a greater understanding of the interaction capacity between antigenic peptides and HLA-DR molecules in the presentation process and consequent production of alloantibodies.