Recognition of LCLs by EBV-specific CD8⁺T-cell clones from XLP patients or healthy carriers. ELISA assays were used to estimate IFN-γ secretion from CD8⁺ T-cell clones incubated overnight with the different target LCLs. (A) IFN-γ secretion by KRP-specific T-cells from a healthy carrier (left panel) or 2 independently derived clones from XLP1 that had been incubated with either XLP1's LCL, an HLA mismatched LCL, or KRP-peptide sensitized XLP1 LCL. (B) IFN-γ secretion by EPL-specific T cells from a healthy carrier (left panel) or 2 independently derived clones from XLP1 that had been incubated with either an HLA B35 matched LCL (BZ⁺ LCL), an HLA B35 matched BZLF1 knock out EBV lytic antigen–negative LCL (ΔBZ LCL), or HLA B35 matched EPL peptide–sensitized LCL. IFN-γ secretion by (C) GLC-specific T cells and (D) YVL-specific T cells from a healthy carrier (left panels) or 2 independently derived clones from XLP8 that had been incubated with either an HLA A2 matched LCL (BZ⁺ LCL), an HLA A2–matched BZLF1 knockout EBV lytic antigen–negative LCL (ΔBZ LCL), or an HLA–A2 matched LCL sensitized with the appropriate peptide.