RESUMO
BACKGROUND: HLA class I molecules are divided into classic (Ia) and nonclassic (Ib). Nonclassic HLA molecules (E, F, and G) have acquired relevance owing to their immunomodulatory properties and possible repercussions for induction of tolerance in organ transplantation. The objective of this study was to identify the impact of these molecules on transplant success or failure. METHODS: A systematic review of literature was performed with the use of MeSH terms in Pubmed. Clinical trials, randomized clinical trials, case-control studies, and reviews from the past 15 years were included. RESULTS: HLA-E*0103/E*0103 genotype is associated with lower risk of graft-versus-host disease, decreased mortality, and greater disease-free survival after bone marrow transplantation. There were no significant associations between HLA-F and clinical outcomes in any of the studies. Elevated serum levels of HLA-G were associated with a lower incidence of rejection in hepatic and renal transplantation during the 1st year and lower T-cell response after bone marrow, liver, and kidney transplantation. Detection of mRNA of HLA-G1 was also associated with less graft rejection. CONCLUSIONS: Current literature suggests that nonclassic HLA Ib molecules play an important role in immunotolerance in organ transplantation; however, more studies are required to predict outcomes related to specific genotypes.
Assuntos
Transplante de Medula Óssea/mortalidade , Rejeição de Enxerto/imunologia , Doença Enxerto-Hospedeiro/imunologia , Antígenos HLA-G/imunologia , Antígenos de Histocompatibilidade Classe I/imunologia , Transplante de Órgãos/mortalidade , Intervalo Livre de Doença , Genótipo , Rejeição de Enxerto/genética , Doença Enxerto-Hospedeiro/genética , Antígenos HLA-G/genética , Antígenos HLA-G/metabolismo , Antígenos de Histocompatibilidade Classe I/genética , Antígenos de Histocompatibilidade Classe I/metabolismo , Humanos , Tolerância Imunológica , Transplante de Rim/mortalidade , Transplante de Fígado/mortalidade , Avaliação de Resultados em Cuidados de Saúde , Antígenos HLA-ERESUMO
Progress in transplantation has relied on similar human leukocyte antigen (HLA) matching between the donor and the patient, while the role of other immunologic factors like non-HLA markers including minor histocompatibility antigens (miHA) are currently in the forefront. miHA are polymorphic proteins that vary even in monozygotic twins. The best known is the H-Y antigen, but there are also other autosomal miHA and MICA (MHC class I chain-related gene A). miHA have been well studied in transplantation of hematopoietic precursors, but not in solid organ transplantation. The most important studies in this field relate to incompatibility of H-Y antigen as a risk factor in kidney transplantation, although the findings are still inconclusive. This review presents the role of minor histocompatibility antigens in solid organ transplantation, especially of the kidney.