HLA-E–restricted T cells primed by a modified HLA-B*57:01–restricted HIV-1 peptide suppress HIV-1 replication
Hong Sun, Hongbing Yang, Max N. Quastel, Simon Brackenridge, Wanlin He, Anna E. Kliszczak, Margarida Rei, Persephone Borrow, Geraldine M. Gillespie, Andrew J. McMichael
Hong Sun, Hongbing Yang, Max N. Quastel, Simon Brackenridge, Wanlin He, Anna E. Kliszczak, Margarida Rei, Persephone Borrow, Geraldine M. Gillespie, Andrew J. McMichael
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Research Article AIDS/HIV Immunology

HLA-E–restricted T cells primed by a modified HLA-B*57:01–restricted HIV-1 peptide suppress HIV-1 replication

Abstract

HLA-E–restricted HIV-specific T cells offer exciting possibilities for immunotherapy. However, HLA-E binding peptides are rare. A recent study showed that in HLA-B*57:01–positive people with HIV, the peptide that dominates the T cell response, KAFSPEVIPMF (KF11), also stimulates HLA-E–restricted T cells, even though direct binding of this peptide to HLA-E could not be demonstrated. We therefore changed position 2 alanine for methionine in the peptide (referred to as KMF11), which greatly enhanced binding to HLA-E. This enabled the generation of stabilized HLA-E-KMF11 tetramers, which were used to select and then grow specific T cell clones from T cells of HLA-B*57:01–negative blood donors primed with this peptide in vitro. Approximately 20% of these T cell clones reacted with HLA-E–positive cells presenting the native KF11 peptide. Furthermore, these T cells inhibited replication of HIV-1 NL4-3 in CD4+ T cells in vitro. Therefore, this native peptide can be presented by HLA-E to CD8+ T cells, although priming in vivo may depend on cross-reactivities to classical MHC-Ia types. Nevertheless, such T cells could be exploitable for immunotherapy given the conservation of this HIV-1 peptide epitope and the non-polymorphism in HLA-E.

Authors

Hong Sun, Hongbing Yang, Max N. Quastel, Simon Brackenridge, Wanlin He, Anna E. Kliszczak, Margarida Rei, Persephone Borrow, Geraldine M. Gillespie, Andrew J. McMichael

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Figure 1

Identification of a mutant peptide of HIV Gag-derived KF11 as an HLA-E binding peptide.

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Identification of a mutant peptide of HIV Gag-derived KF11 as an HLA-E b...
(A) Binding of the HIV Gag162-172 KAFSPEVIPMF (KF11) to HLA-E was evaluated using the single chain trimer (SCT) expression assay with VMAPRTLLL (VL9) included as a positive control. (B) The thermal melt (Tm) values of peptide-free HLA-E-β2m complexes incubated with 10 M excess of KF11 and the peptide position 2 alanine to methionine variant peptide (KMF11) was assessed by nano-differential scanning fluorography (nano-DSF). The positive control VL9 and mock no-peptide control were included for reference. The dot plot shows 3 biological replicates per peptide, presented as mean ± SD. Two technical replicates per peptide were measured per run. (C) Flow cytometry analysis of SCT expression demonstrated the binding potential of the mutant peptide KMF11 compared with the VL9 positive control. (D) HLA-E binding to KF11 and KMF11 were subsequently assessed using the peptide-exchange HLA-E peptide binding ELISA (25). The bar chart illustrates the raw absorbance value at 450 nm (y axis) of tested peptides, including KF11, KMF11, RL9HIV, positive control VL9, and no-rescue negative control, which included the same concentration of DMSO used for the test peptides (x axis). Data shown as mean ± SD. Statistical significance was assessed using 1-way ANOVA with Dunnett’s multiple-comparison test. ****P < 0.0001. For ELISA-based screens, 3 independent peptide exchange reactions were performed per individual peptide (n = 3), with 2 technical replicas per peptide tested. (E) The heatmap denotes the ranking of HLA-E binding strength data obtained using the sandwich ELISA, indicated as percentage of VL9 binding. (F) Correlation of peptide-exchange HLA-E peptide binding ELISA reads and nano-DSF assay Tm data using Spearman’s correlation method. VL9, blue; KF11, pink; KMF11, red; RL9HIV, green; no-rescue, gray.