HLA-Cw*0102-restricted HIV-1 p24 epitope variants can modulate the binding of the inhibitory KIR2DL2 receptor and primary NK cell function

PLoS Pathog. 2012;8(7):e1002805. doi: 10.1371/journal.ppat.1002805. Epub 2012 Jul 12.

Abstract

Accumulating evidence suggests an important role for Natural Killer (NK) cells in the control of HIV-1 infection. Recently, it was shown that NK cell-mediated immune pressure can result in the selection of HIV-1 escape mutations. A potential mechanism for this NK cell escape is the selection of HLA class I-presented HIV-1 epitopes that allow for the engagement of inhibitory killer cell immunoglobulin-like receptors (KIRs), notably KIR2DL2. We therefore investigated the consequences of sequence variations within HLA-Cw*0102-restricted epitopes on the interaction of HLA-Cw*0102 with KIR2DL2 using a large panel of overlapping HIV-1 p24 Gag peptides. 217 decameric peptides spanning the HIV-1 p24 Gag consensus sequence were screened for HLA-Cw*0102 stabilization by co-incubation with Cw*0102⁺/TAP-deficient T2 cells using a flow cytometry-based assay. KIR2DL2 binding was assessed using a KIR2DL2-IgG fusion construct. Function of KIR2DL2⁺ NK cells was flow cytometrically analyzed by measuring degranulation of primary NK cells after co-incubation with peptide-pulsed T2 cells. We identified 11 peptides stabilizing HLA-Cw*0102 on the surface of T2 cells. However, only one peptide (p24 Gag₂₀₉₋₂₁₈ AAEWDRLHPV) allowed for binding of KIR2DL2. Notably, functional analysis showed a significant inhibition of KIR2DL2⁺ NK cells in the presence of p24 Gag₂₀₉₋₂₁₈-pulsed T2 cells, while degranulation of KIR2DL2⁻ NK cells was not affected. Moreover, we demonstrated that sequence variations in position 7 of this epitope observed frequently in naturally occurring HIV-1 sequences can modulate binding to KIR2DL2. Our results show that the majority of HIV-1 p24 Gag peptides stabilizing HLA-Cw*0102 do not allow for binding of KIR2DL2, but identified one HLA-Cw*0102-presented peptide (p24 Gag₂₀₉₋₂₁₈) that was recognized by the inhibitory NK cell receptor KIR2DL2 leading to functional inhibition of KIR2DL2-expressing NK cells. Engagement of KIR2DL2 might protect virus-infected cells from NK cell-mediated lysis and selections of sequence polymorphisms that increase avidity to KIR2DL2 might provide a mechanism for HIV-1 to escape NK cell-mediated immune pressure.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • Cytotoxicity, Immunologic
  • Genetic Variation
  • HIV Core Protein p24 / genetics
  • HIV Core Protein p24 / immunology*
  • HIV Core Protein p24 / metabolism
  • HIV Infections / immunology
  • HIV-1 / genetics
  • HIV-1 / immunology*
  • HIV-1 / metabolism
  • HLA-C Antigens / immunology*
  • Humans
  • Immune Evasion
  • Killer Cells, Natural / immunology*
  • Protein Binding
  • Receptors, KIR2DL2 / metabolism*
  • Sequence Alignment

Substances

  • HIV Core Protein p24
  • HLA-C Antigens
  • HLA-C*01:02 antigen
  • KIR2DL2 protein, human
  • Receptors, KIR2DL2