No cross-reactivity between PD-L1-specific and PD-L2-specific T cells. (A) The first 30 amino acid sequences of PD-L1 and PD-L2 and the location of the peptides PD-L101 (PDL115-23; LLNAFTVTV) and PD-L205 (PD-L216-25; QIAALFTVTV) in the signal peptide part of the proteins are marked in bold. (B) In vitro IFN- γ ELISPOT results show responses of T cells from five patients with cancer towards PD-L101 (PDL115-23) and PD-L205 (PD-L216-25) peptides. (C) 51Cr-release assay results show percent lysis of T2 cells pulsed with PD-L101 (PDL115-23), PD-L205 (PD-L216-25), or an irrelevant HIV peptide (HIV-1 pol476-484) when exposed to PD-L101-specific T-cells (CTLs) at different effector-to-target ratios. (D) Intracellular cytokine staining of cultured PD-L101-specific T-cells shows CD8+ T cell release of TNF-α, upon exposure to PD-L101 (PDL115-23), PDL205 (PD-L216-25), or an irrelevant HIV peptide (HIV-1 pol476-484). (D) Percent lysis of T2-cells, pulsed with PDL205 (PD-L216-25), PD-L101 peptide (PDL115-23), or an irrelevant HIV peptide (HIV-1 pol476-484), after exposure to PD-L2T-cell culture-A (left) or PD-L2T-cell culture-B (right).