HLA Matching in Unrelated Stem Cell Transplantation up to Date

Abstract

Unrelated hematopoietic stem cell transplantation (HSCT) has evolved from an experimental protocol to a potentially curative first-line treatment in certain disease instances. Factors enabling this transformation were the optimization of treatment protocols and supportive care as well as the availability of a large number of donors worldwide along with the higher quality and reliability of HLA typing. The main criterion for donor selection is HLA compatibility. In this review we discuss the current clinical evidence of HLA matching in unrelated HSCT. In this context, we address methodical aspects of transplantation immunobiology research and discuss the impact of locus and resolution of HLA differences. Furthermore, we address special constellations such as unidirectional mismatches or the presence of nonexpressed alleles as well as HLA alloimmunization and describe the perspective for HLA typing and matching strategies in the future, given the implementation of novel complete or near-complete gene typing approaches using next-generation sequencing short read technology, which are now entering the standard of clinical care.

Class I/Class II HLA Evolutionary Divergence Ratio Is an Independent Marker Associated With Disease-Free and Overall Survival After Allogeneic Hematopoietic Stem Cell Transplantation for Acute Myeloid Leukemia

“…While advances in HLA typing have improved HLA matching and enhanced graft attribution (19,20), relapse after HCT remains frequent and is still subject to uncertain outcomes. The balance between GVL and GVHD is a key point governing HCT success.…”

A concise review on factors influencing the hematopoietic stem cell transplantation main outcomes

“…The main criterion for donor selection in allogenic HSCT is the HLA compatibility. 5 Both types of HLA are located on the short arm of chromosome 6 (Figure 2) and are expressed on most of the cells, particularly hematopoietic cells for recognition of foreign antigens. 6,7 Compatible HLA reduces the risk of GVHD, graft failure, the mortality rate, and increases disease-free survival (DFS).…”

The novel HLA‐DRB1*03:178, ‐DRB1*03:179, and ‐DRB1*11:276 alleles identified in a healthy Brazilian individuals

“…Approximately 8500 class II HLA alleles were officially recognized in the IPD‐IMGT/HLA Database (release 3.46, 2021‐10) 1 . The higher quality and reliability of HLA typing obtained by next‐generation sequencing of the complete HLA gene has contributed to improve the outcomes of hematopoietic stem cell transplantation (HSCT) 2,3 . In this report, we describe the full‐length sequence of three new HLA class II alleles in the healthy Brazilian individuals.…”