Fig. 4

Binding of endogenously processed p53_125–134/A24 pMHCs on cells expressing wild-type and mutant p53. a Colon carcinoma cell line HT29 expressing HLA-A24 and mutant p53^R273H, osteosarcoma cell line SaoS2 expressing HLA-A24 with a null mutation of the p53 gene, while hepatocellular carcinoma cell line HepG2-expressing HLA-A24 and wild-type p53 were stained with 10 µg mL⁻¹ P1C1TM. Significant staining was observed only with HT29 cells and minimal staining or no staining was seen with HepG2 and SaoS2 cells, respectively. HLA-A24-negative breast cancer cell lines MDA-MB-231, BT474 and MCF7, and lung carcinoma cell line A549 were transduced with HLA-A24. Staining of the untransduced (b) and transduced (c) cells with P1C1TM showed significantly higher levels of p53_125–134/A24 pMHCs on the surface of cells expressing both HLA-A24 and mutant p53 (MDA-MB-231 and BT474) compared to cells expressing wild-type p53 (A549 and MCF7). Insets show P1C1TM staining of the respective cell lines pulsed with 10 μM of p53_125–134 peptides, indicating successful transduction. Data are representative of three independent experiments. d P1C1TM was used to stain HLA-A24⁺ PBMCs. No significant binding was observed in unpulsed PBMCs. P1C1TM staining was observed when pulsed with 10 µM p53_125–134 peptides but not control peptides. e Staining of P1C1TM was observed only in activated HLA-A24⁺ T cells, but not resting HLA-A24⁺ T cells or activated HLA-A24⁻ T cells.