C-C chemokine receptor 4 (CCR4)-positive regulatory T cells interact with tumor-associated macrophages to facilitate metastatic potential after radiation.

Purpose: Our previous study revealed that elevated C-C motif chemokine ligand 2 (CCL2) secretion by irradiated cancer cells recruited C-C motif chemokine receptor 2 (CCR2)-positive myeloid cells and polarized M2-type tumor-associated macrophages (TAMs), promoting lung metastasis in an established mouse model. This study investigated the impact of CCL2 and TAMs on adaptive immunity.

Methods: We assessed the influence of CCL2 and TAMs on adaptive immunity through two ectopic allograft mouse models constructed with MB49 bladder cancer cells and Lewis lung carcinoma cells.