title: Human melanoma-specific CD8(+) T-cells from metastases are capable of antigen-specific degranulation and cytolysis directly ex vivo.
abstract: The relatively low frequencies of tumor Ag-specific T-cells in PBMC and metastases from cancer patients have long precluded the analysis of their direct ex vivo cytolytic capacity. Using a new composite technique that works well with low cell numbers, we aimed at determining the functional competence of melanoma-specific CD8(+) T-cells. A multiparameter flow cytometry based technique was applied to assess the cytolytic function, degranulation and IFNγ production by tumor Ag-specific CD8(+) T-cells from PBMC and tumor-infiltrated lymph nodes (TILN) of melanoma patients. We found strong cytotoxicity by T-cells not only when they were isolated from PBMC but also from TILN. Cytotoxicity was observed against peptide-pulsed target cells and melanoma cells presenting the naturally processed endogenous antigen. However, unlike their PBMC-derived counterparts, T-cells from TILN produced only minimal amounts of IFNγ, while exhibiting similar levels of degranulation, revealing a critical functional dichotomy in metastatic lesions. Our finding of partial functional impairment fits well with the current knowledge that T-cells from cancer metastases are so-called exhausted, a state of T-cell hyporesponsiveness also found in chronic viral infections. The identification of responsible mechanisms in the tumor microenvironment is important for improving cancer therapies.
authors: Ludwig Center for Cancer Research; University of Lausanne; Lausanne, Switzerland.
authors: Yolanda D
authors: YD
authors: Mahnke
authors: Estelle
authors: E
authors: Devevre
authors: Petra
authors: P
authors: Baumgaertner
authors: Maurice
authors: M
authors: Matter
authors: Nathalie
authors: N
authors: Rufer
authors: Pedro
authors: P
authors: Romero
authors: Daniel E
authors: DE
authors: Speiser