Table 1.

Highlighting the effects of IR on various immune cell types. Different immune cell types from the tumor microenvironment are listed, along with examples of reported effects of IR on their function.

Cell Type Influenced	Cancer Model	Radiation Dose	Response Observed	Ref.
APC	Murine pancreatic cancer tumor	4 × 6 Gy fractions	Increases in calreticulin and HMGB1 corresponded with elevated tumor-antigen presentation and increased CD8+ T cell inflitration into the tumor	[34]
	Murine colorectal tumor	20 Gy × 1 fraction	STING-dependent increases in antigen presentation by dendritic cells facilitate CD8+ T cell anti-tumor immune responses	[54]
	Murine melanoma tumor	10 Gy × 1 fraction	Depletion of dendritic cells prevented IR efficacy by preventing CD8+ T cell infiltration into the tumor	[128]
MDSC/Macrophage	Murine colorectal tumor	20 Gy × 1 fraction	Monocytic MDSC increases in the tumor and mediates radioresistence by inhibiting CD4+ and CD8+ T cell function	[68]
	Murine prostate tumor	25 Gy × 1 fraction or 4 Gy × 15 fractions	Increases in arginase, iNOS and COX-2 expression on intratumoral macrophages	[99]
	Murine melonoma tumor	15 Gy × 1 fraction or 5 Gy × 3 fractions	Increase in macrophage infiltration to the tumor	[100]
Neutrophil	Murine soft tissue sarcoma	20 Gy × 1 fraction	Depleting neutrophils prior to IR improved treatment efficacy	[114]
	Murine prostate, lymphoma and mammary tumors	15 Gy × 1 fraction (prostate and mammary cancers) and 1.3 Gy × 1 fraction for lymphoma	Increase in neutrophil infiltration into tumors which mediate tumor cell apoptosis via ROS production	[116]
	Murine lung tumor	8 Gy × 3 fractions	Increase in neutrophil inflitration into tumors, which promotes the mesenchymal-to-epithelial transition in cancer cells via ROS production	[117]
	Murine bladder tumor	2 Gy × 1 fraction, 5 Gy × 2 fractions or 10 Gy × 1 fraction	Increased production of neutrophil extracellular traps that mediate radioresistence by inhibiting CD8+ T cell tumor infiltration	[121]
T cell	Murine melanoma tumor	10 Gy × 1 fraction	Depleting CD8+ T cells abrogates treatment efficacy	[128]
	Murine colon tumor	15 Gy in 1 fraction	Depleting CD8+ T cells abrogates treatment efficacy	[13]
	Human pancreatic cancer patients	5 Gy × 5 fractions	T cell clonal expansion in a subset of patients	[132]
	Human renal cell carcinoma patients	15 Gy × 1 fraction	T cell clonal expansion	[131]
NK cell	Human pancreatic cancer patients	54 Gy (median dose) × 24 fractions	Increase in NK cell infiltration into tumors	[153]
	Human melanoma cells implanted into mice	16 Gy × 1 fraction	Irradiated cancer cells prevent NK-mediated cell toxicity	[157]
B cell	Murine colon and oral squamous cell tumors	10 Gy × 1 fraction	Increase in B cell infiltration into tumors	[172]
	Murine squamous cell tumors	12–18 Gy × 1 fraction	Increases in tumor antigen-specific B cells and depleting B cells antagonizes IR efficacy.	[173]