Pre-existing intratumoral stem-like CD8+ T-Cells drive radiotherapy-induced tumor control

To evaluate how intratumoral CD8+ T-cells are influenced by radiotherapy, we performed single-cell RNA sequencing of CD8+ T-cells sorted from MC38-OVA tumors 6 days after radiotherapy (single dose, 20Gy). Overall design: Intratumoral CD8+ T-cells (live, CD45+, CD8+) were isolated by fluorescence-activated cell sorting (FACS) 6 days after radiotherapy. We used four conditions: irradiated (RT, 8 mice), untreated (UNTR, 8 mice), and two groups where lymphocyte infiltration was blocked with FTY720, labeled RT+FTY (8 mice) and UNTR+FTY (7 mice). Cells from each sample were labeled with the BD Single-Cell Multiplexing Kit and pooled based on their respective conditions. Conditions with FTY and without were sequenced at different times.