Chapter 9 - Human leukocyte antigen-typing: a significant immunogenetic application in clinical medicine

Abstract

Our immune system is capable of reacting to both foreign antigens and acquired antigens produced by cancer cells, making it vital for maintaining good health and combating disease. Human leukocyte antigen (HLA) system, the human version of the major histocompatibility complex, which plays an important role in immune surveillance, has been extensively researched for their functions in transplantation biology and other clinical aspects. The HLA system plays an important role in regulating the immune response. Because of its role in immune regulation and its ability to exhibit tremendous polymorphism, the HLA system acts as the biggest immunological barrier that needs to be avoided for a successful transplant. HLA typing has therefore found its place in clinical immunology as one of the emerging fields. HLA class I and class II allele matching in transplantation between unrelated donors is performed on a regular basis using molecular HLA allele typing. Moreover, prospective lymphocyte cross-matching is one of the major steps performed to avoid allograft rejections in solid organ transplantation. HLA alloimmunization also induces complications in transfusion therapy. HLA typing techniques have evolved from earlier ones, such as serology-based techniques, to sequence-based typing, and finally to next-generation sequencing. Cross-matching techniques have progressed from complement-dependent cytotoxicity (which is still considered the gold standard) to microbead-based assays to a much more advanced one, flow cytometry. Furthermore, the HLA system is related to a variety of diseases; however, the underlying mechanisms are still unclear. As the control of the HLA is elucidated, new and effective immunomodulatory therapies will be developed and used to enhance transplantation, transfusion, and other immunotherapeutic applications. This chapter provides a brief summary of the applications of HLA typing in clinical immunobiology.