Figure 6.

Direct tumor recognition by phosphorylated peptide-specific CD4 T-cells. Direct tumor recognition of naturally processed p53 antigen expressed in tumor cells by p-p53_S33-reactive clones (K2 and J44) and the p-p53_S37-reactive clone (H2). (A) p-p53_S33-reactive T cells (K2 and J44, DR-1-restricted) were tested for their capacity to recognize HLA-DR1⁺/p53 positive (HSC4, LC-2/ad and 5637) or DR1⁺/p53 negative (EBC1) tumor cells, which was used as a negative control. The p-p53_S37-reactive clone (H2) was tested for its capacity to recognize antigens directly on HLA-DR9⁺/p53 positive tumor cells (Sa3, 5637) or DR9⁺/p53 negative (SAS) tumor cells. (B) Tumor cells were treated with doxorubicin or cisplatin 24 hours before coculture with T cells (K2, J44 and H2). (C) Granzyme B production by the p-p53_S33-reactive clone (J44) during coculture with tumor cells.