Abstract 4788: Modulation of T lymphocytes by tumor-released survivin

Introduction: The role of tumor infiltrating lymphocytes (TILs) in the progression of cancer has become an important area of research. Recent studies have shown that T lymphocytes within the tumor microenvironment have decreased activation and proliferation. Our lab has shown survivin is released from tumor cells within exosomes, and is capable of altering the phenotype of malignant cells. We hypothesize that this exosomally-released survivin prevent TIL activation and proliferation in T cell subsets and that Th2 type cytokines will be released in higher levels than Th1 cytokines. Methods: HeLa-S-WT cells that produce Flag-HA tagged survivin were growth in a bioreactor and survivin isolated from the media using Flag-HA tandem affinity purification. T lymphocytes from normal donors were cultured in control or survivin-containing media and activated with anti-CD28-anti-CD3 microbeads (32 ul/ml). Flow cytometric analysis of activation marker CD69 and the proliferation marker Ki-67 were performed at 24h and 6 days, respectively. Cytokine release was evaluated using a Cytokine Bead Array (BD Bioscience) for IFN-gamma, IL-2, IL-4 and IL-10. Results: CD69 expression was decreased significantly in CD8+ T cells after incubation with survivin (Control = 72 MFU, Treated = 57 MFU; p<0.05) while no significant change was seen in CD4+ T cells (Control = 65 MFU, Treated = 68 MFU). CD8+ T cells showed a significant reduction in Ki-67 expression after incubation with survivin when compared to controls (Control = 218 MFU, Treated = 139 MFU; p < 0.001), while CD4+ T cells showed little difference between control and treated groups (Control = 74 MFU, Treated = 81 MFU). Cells treated with survivin in activating conditions released higher amounts of IL-4 (Control = 4.8 pg/ml, Treated = 28.3 pg/ml) and decreased amounts of IFN-gamma (Control = 32.4 pg/ml, Treated = 16.9 pg/ml) compared to control activating conditions. IL-2 and IL-10 showed little difference between treatment groups. Conclusions: This data suggests that survivin in the tumor microenvironment is capable of negatively affecting cytotoxic T cell activation and proliferation. While survivin treatment does not affect the activation or proliferation of CD4+ subsets, the Th1: Th2 cytokine balance is altered when survivin is present. Thus, survivin in the tumor microenvironment could play a role in the suppression of immune surveillance by inhibiting the cytotoxic T cell response and preventing tumor death by increasing levels of Th2 cytokines and decreasing levels of Th1 cytokines.Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4788.