High expression of HLA-E in colorectal carcinoma is associated with a favorable prognosis

J Transl Med. 2011 Oct 27;9:184. doi: 10.1186/1479-5876-9-184.

Abstract

Background: Human Leukocyte Antigen (HLA)-E is a non-classical class I HLA molecule that can be stabilized by ligands donated by other classical (HLA-A, -B, -C) and non-classical (HLA-G) family members. HLA-E engages a variety of immune receptors expressed by cytotoxic T lymphocytes (CTLs), Natural killer (NK) cells and NK-CTLs. In view of the opposing outcomes (activation or inhibition) of the different HLA-E receptors, the preferred role (if any) of HLA-E expressed in vivo on tumor cells remains to be established.

Methods: Taking advantage of MEM-E/02, a recently characterized antibody to denatured HLA-E molecules, HLA-E expression was assessed by immunohistochemistry on an archival collection (formalin-fixed paraffin-embedded) of 149 colorectal primary carcinoma lesions paired with their morphologically normal mucosae. Lymphoid infiltrates were assessed for the expression of the HLA-E-specific, inhibitory, non-rearranging receptor NKG2A.

Results: High HLA-E expression did not significantly correlate with the expression of classical HLA-B and HLA-C molecules, but it did correlate with high expression of its preferential ligand donor HLA-A. In addition, it correlated with lymphoid cell infiltrates expressing the inhibitory NKG2A receptor, and was an independent predictor of good prognosis, particularly in a subset of patients whose tumors express HLA-A levels resembling those of their paired normal counterparts (HLA-A). Thus, combination phenotypes (HLA-Elo-int/HLA-AE and HLA-Ehi/HLA-AE) of classical and non-classical class I HLA molecules mark two graded levels of good prognosis.

Conclusions: These results suggest that HLA-E favors activating immune responses to colorectal carcinoma. They also provide evidence in humans that tumor cells entertain extensive negotiation with the immune system until a compromise between recognition and escape is reached. It is implied that this process occurs stepwise, as predicted by the widely accepted 'immunoediting' model.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Alleles
  • Antibodies / immunology
  • CD8 Antigens / immunology
  • Colorectal Neoplasms / diagnosis*
  • Colorectal Neoplasms / immunology*
  • Colorectal Neoplasms / pathology
  • Female
  • Histocompatibility Antigens Class I / genetics
  • Histocompatibility Antigens Class I / immunology*
  • Humans
  • Immunohistochemistry
  • Intestinal Mucosa / immunology
  • Intestinal Mucosa / pathology
  • Kaplan-Meier Estimate
  • Male
  • Middle Aged
  • Models, Immunological
  • Multivariate Analysis
  • NK Cell Lectin-Like Receptor Subfamily C / immunology
  • Neoplasm Staging
  • Paraffin Embedding
  • Prognosis
  • Tissue Fixation

Substances

  • Antibodies
  • CD8 Antigens
  • HLA-E antigen
  • Histocompatibility Antigens Class I
  • NK Cell Lectin-Like Receptor Subfamily C