Abstract 1347: Genomic stress in antigen experienced T-lymphocytes

Abstract

Abstract DNA damage response and repair (DDR) pathways are central to biological processes like hematopoietic stem cell maintenance, lymphocyte development and adaptive response to inflammation and cancer. However, the role of DDR in antigen experienced T-lymphocytes remains unclear. We studied the dynamics of DDR response during CD8+ T cell proliferation and differentiation. We found that DDR gene transcripts and gamma-H2AX, a marker for DDR pathway activation, are significantly up-regulated in CD8+ T cells expanded in-vitro and in-vivo. Next we aimed to determine the consequence of the activation of DDR pathways. Based on flow cytometry measurements of gamma-H2AX phosphorylation levels, we categorized CD8+ T cells into gamma-H2AXLo and gamma-H2AXHi cells. gamma-H2AXLo CD8+ T cells actively proliferate and produce cytokines, while gamma-H2AXHi CD8+ T cells lose their ability to produce cytokines, and undergo apoptosis. To define whether oxidative stress or replicative stress incurred in CD8+ T cell triggers this activation of DDR, we acutely treated cells with chemical agents and studied functional differences. These studies revealed that oxidative stress may be responsible for the inhibition of cytokine production and increase in cell death. Using Pmel transgenic p53-/- mouse model, we show that by deleting p53, a major signal modulator of DDR, the loss of cytokine production and cell death due to oxidative stress is reverted in CD8+ T cells. Currently, we are exploring the chemical and gene modification methods to manage oxidative stress in CD8+ T cells to improve T-cell based adoptive cell transfer therapies for cancer. Citation Format: Shashank Patel, Madhusudhanan Sukumar, Douglas Palmer, Rahul Roychoudhari, Rabindra Roy, Andre Nussenzweig, Nicholas Restifo. Genomic stress in antigen experienced T-lymphocytes. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1347. doi:10.1158/1538-7445.AM2015-1347