Combined analysis of T cell activation and T cell-mediated cytotoxicity by imaging cytometry

Abstract Immunotherapies have transformed the treatment of cancer through the development of drugs that allow T cells to recognize and kill malignant cells. With this has come a need to evaluate how these drugs affect T cell function. We developed an imaging cytometry-based method that can simultaneously assess T cell activation and the functional ability of these activated T cells to kill cancer cells. We used the Nur77-GFP reporter, which expresses GFP upon T cell receptor signaling, as a readout of T cell activation. We combined this reporter system with an MC38 colon adenocarcinoma cell line expressing a TCR-specific antigen that is used as a model tumor antigen (TA). We show that in T cell-cancer co-culture systems, we are able to quantify the number of activated cytotoxic CD8+ T cells and their ability to recognize and kill cancer cells by imaging cytometry. We tested the sensitivity of this platform by quantifying the proportion of antigen-specific activated T cells in co-cultures with varying ratios of unresponsive T cells, mimicking heterogenous lymphocyte populations. To test our system in a pharmacological context, we evaluated the effects of a SRC family kinase inhibitor on T cell activation and cancer cell death. In each case, we were able to quantify the proportion of activated T cells and the extent of TA-specific cancer cell death. Our findings show that the Nur77-GFP reporter system combined with imaging cytometry is a fast and reproducible system to evaluate how different treatment conditions influence TA recognition by T cells using T cell-cancer co-cultures. The simultaneous analysis of T cell activation with T cell-mediated cancer cell death can be used to rapidly assess immuno-oncology drug candidates and T cell-based therapeutics. Supported by The Elsa U. Pardee Foundation (AHC), the V Foundation Scholar Award (AHC), the Cancer Biology Training Program T32CA009676 (MKC), the Pharmacological Sciences Training Program T32GM140223 (CES), and a Charles W. Edmunds Pharmacology Fellowship (YZ). This study was also supported by resources provided by the U-M Flow Cytometry Core and the U-M Rogel Cancer Center (P30CA046592).