NanoSTRING analysis of sorted intratumoral CD8+ T cells following radiotherapy

The recruitment of monocytes and their differentiation into immunosuppressive cells is associated with the negative outcome of non-conformal radiotherapy (RT). However, non-conformal RT is irrelevant in the clinic, and little is known about the role of monocytes following radiotherapy modes used in patients, such as conformal radiotherapy (CRT). Here, we investigated the acute immune infiltration post-CRT. Contrary to non-conformal RT approaches, we found that CRT induces a rapid and robust recruitment of monocytes to the tumor that minimally differentiate into tumor-associated macrophages (TAM) or dendritic cells (DC), but instead upregulate major histocompatibility complex II (MHCII) and costimulatory molecules. We establish that these large numbers of infiltrating monocytes are responsible for increasing type I interferon in the tumor microenvironment (TME), activation of CD8+ T cells and the reduction in tumor burden. Importantly, we demonstrate that rapid monocyte infiltration to the TME is hindered when RT inadvertently affects healthy tissues. Our results unravel a positive role of monocytes during clinically relevant modes of RT and demonstrate that limiting exposure of healthy tissues to radiation has a positive therapeutic effect on the overall immune response within the tumor. The objective of this experiment was to evaluate the transcriptional changes in CD8+ T cells following different modes of radiation at 3 days post treatment Three different modes of radiatherapy in triplicate. Control samples are marked as Nontreated