In chronic viral infections, CD8+ T cells become functionally deficient and display multiple molecular alterations. In contrast, only little is known of self- and tumor-specific CD8+ T cells from mice and humans. Here we determined molecular profiles of tumor-specific CD8+ T cells from melanoma patients. In peripheral blood from patients vaccinated with CpG and the melanoma antigen Melan-A/MART-1 peptide, we found functional effector T cell populations, with only small but nevertheless significant differences in T cells specific for persistent herpesviruses (EBV and CMV). In contrast, Melan-A/MART-1–specific T cells isolated from metastases from patients with melanoma expressed a large variety of genes associated with T cell exhaustion. The identified exhaustion profile revealed extended molecular alterations. Our data demonstrate a remarkable coexistence of effector cells in circulation and exhausted cells in the tumor environment. Functional T cell impairment is mediated by inhibitory receptors and further molecular pathways, which represent potential targets for cancer therapy.
Lukas Baitsch, Petra Baumgaertner, Estelle Devêvre, Sunil K. Raghav, Amandine Legat, Leticia Barba, Sébastien Wieckowski, Hanifa Bouzourene, Bart Deplancke, Pedro Romero, Nathalie Rufer, Daniel E. Speiser