HLA System and Transfusion Medicine: Molecular Approach

Abstract

The genetic loci involved in the rejection of an allograft are known as the major histocompatibility complex (MHC), and highly polymorphic cell surface molecules are encoded by the MHC. The human MHC is called the human leukocyte antigen (HLA) system. The biological role of the polymorphic HLA molecules is to present various peptide antigens to lymphocytes that resulting immune responses can handle these antigens, but HLA polymorphism is an immunological barrier in the allogeneic transplantation setting. Clinical HLA testing is performed to avoid the immunological adverse consequences of transplantation across HLA disparity. HLA allele matching by the use of molecular HLA typing methods is the most important factor to achieve successful hematopoietic stem cell transplantation. In contrast, avoiding an HLA incompatible organ by the use of HLA antibody testing and lymphocyte crossmatch is the most critical step in solid organ transplantation in order to prevent or reduce the risks of rejection.