Figure 2. Recognition of KF11 in the context of HLA-E*01 by non-NK/NKT CD8⁺ T cells from HIV-infected individuals, using the 221^ΔE cell panel and in vitro–generated CD8⁺ T cell lines.

(A) In vitro–cultured CD8⁺ T cells from 4 chronically HIV-infected individuals (CHI-12, CHI-2, CHI-4, and CHI-24) were tested for upregulation of CD107a/b in CD94-expressing CD8⁺ T cells in response to KF11 (10 μg/mL). APCs or target cells included 221^ΔE.E*01, 221^ΔE.B*57, and 221^ΔE, the latter serving as a negative control. In addition, within each APC, KF11 stimulation was assessed in comparison with no-peptide-pulse control (red boxes). (B) Two different blocking strategies in patient CHI-24 were used to confirm that KF11 was presented in the context of HLA-E. KF11-specific activation of CD8⁺ T cells (IFN-γ production) in the context of HLA-E*01:03 but not HLA-B*57:03 was blocked by excess leader sequence B7sp peptide or by the HLA-E–specific 3D12 mAb, both at 10 μg/mL.