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Journal of Immunology Research
Volume 2014 (2014), Article ID 352160, 7 pages
Review Article

HLA-E: A Novel Player for Histocompatibility

Institute for Transfusion Medicine, Hannover Medical School, Medical Park, Feodor-Lynen-Straße 5, 30625 Hannover, Germany

Received 13 August 2014; Accepted 3 October 2014; Published 20 October 2014

Academic Editor: Naohiro Seo

Copyright © 2014 Thomas Kraemer et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The classical class I human leukocyte antigens (HLA-A, -B, and -C) present allele-specific self- or pathogenic peptides originated by intracellular processing to CD8+ immune effector cells. Even a single mismatch in the heavy chain (hc) of an HLA class I molecule can impact on the peptide binding profile. Since HLA class I molecules are highly polymorphic and most of their polymorphisms affect the peptide binding region (PBR), it becomes obvious that systematic HLA matching is crucial in determining the outcome of transplantation. The opposite holds true for the nonclassical HLA class I molecule HLA-E. HLA-E polymorphism is restricted to two functional versions and is thought to present a limited set of highly conserved peptides derived from class I leader sequences. However, HLA-E appears to be a ligand for the innate and adaptive immune system, where the immunological response to peptide-HLA-E complexes is dictated through the sequence of the bound peptide. Structural investigations clearly demonstrate how subtle amino acid differences impact the strength and response of the cognate CD94/NKG2 or T cell receptor.