A Conserved HIV-1-Derived Peptide Presented by HLA-E Renders Infected T-cells Highly Susceptible to Attack by NKG2A/CD94-Bearing Natural Killer Cells

PLoS Pathog. 2016 Feb 1;12(2):e1005421. doi: 10.1371/journal.ppat.1005421. eCollection 2016 Feb.

Abstract

Major histocompatibility class I (MHC-I)-specific inhibitory receptors on natural killer (NK) cells (iNKRs) tolerize mature NK cell responses toward normal cells. NK cells generate cytolytic responses to virus-infected or malignant target cells with altered or decreased MHC-I surface expression due to the loss of tolerizing ligands. The NKG2A/CD94 iNKR suppresses NK cell responses through recognition of the non-classical MHC-I, HLA-E. We used HIV-infected primary T-cells as targets in an in vitro cytolytic assay with autologous NK cells from healthy donors. In these experiments, primary NKG2A/CD94(+) NK cells surprisingly generated the most efficient responses toward HIV-infected T-cells, despite high HLA-E expression on the infected targets. Since certain MHC-I-presented peptides can alter recognition by iNKRs, we hypothesized that HIV-1-derived peptides presented by HLA-E on infected cells may block engagement with NKG2A/CD94, thereby engendering susceptibility to NKG2A/CD94(+) NK cells. We demonstrate that HLA-E is capable of presenting a highly conserved peptide from HIV-1 capsid (AISPRTLNA) that is not recognized by NKG2A/CD94. We further confirmed that HLA-C expressed on HIV-infected cells restricts attack by KIR2DL(+) CD56(dim) NK cells, in contrast to the efficient responses by CD56(bright) NK cells, which express predominantly NKG2A/CD94 and lack KIR2DLs. These findings are important since the use of NK cells was recently proposed to treat latently HIV-1-infected patients in combination with latency reversing agents. Our results provide a mechanistic basis to guide these future clinical studies, suggesting that ex vivo-expanded NKG2A/CD94(+) KIR2DL(-) NK cells may be uniquely beneficial.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • HIV Infections / immunology*
  • HIV-1 / immunology*
  • HLA-C Antigens / immunology*
  • HLA-E Antigens
  • Histocompatibility Antigens Class I / immunology*
  • Humans
  • Killer Cells, Natural / immunology*
  • NK Cell Lectin-Like Receptor Subfamily D / immunology
  • Peptides / immunology
  • Receptors, Natural Killer Cell / immunology
  • T-Lymphocytes / immunology
  • T-Lymphocytes / virology

Substances

  • HLA-C Antigens
  • Histocompatibility Antigens Class I
  • NK Cell Lectin-Like Receptor Subfamily D
  • Peptides
  • Receptors, Natural Killer Cell