Artikel
Increased Rates of Spontaneous Apoptosis in Tumor-Specific Tetramer+CD8+ T Lymphocytes in the Peripheral Circulation
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Veröffentlicht: | 22. September 2005 |
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Gliederung
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In the circulation of cancer patients T-cells undergo spontaneous apoptosis at a high rate. It is so far unknown, whether these cells are tumor-specific. The objective of our study was to investigate if tumor-specific CD8+ T-cells of patients with SCCHN undergo preferential apoptosis. The peripheral blood lymphocytes of 14 HLA-A2+ Patients were analysed by 4-color-flowcytometry. Frequencies of p53264-272 or p53149-157 CD8+ Tetramer+ T-cells were in the range of 1/776-1/7805. In two cases, frequencies were much higher for p53149-157 Tetramer+ T-cells at a frequency of 1/776 and 1/1006 respectively. Our results further show that a majority of the CD8+ Tetramer+ T-cells are AnnexinV+. 25-95% of the CD8+ Tetramer+ T-cells were AnnexinV+ while only 6-40% of the CD8+ T-cells were apoptotic. The fact that CD8+ Tetramer+ T-cells preferentially bind AnnexinV supports the conclusion that tumor-specific CD8+ T-cells are determined to undergo apoptosis. The increased turnover of tumor-specific T-cells shows the negative influence of SCCHN on the immunologic homeostasis. Our results imply that a specific mechanism is responsible for this phenomenon since tumor-specific T-cells undergo apoptosis at higher rates than the main CD8+ T-cell population. This observation is one more piece of evidence for the negative effects that cancer exerts on the immune system.