CCR2 and neoplasm: A significant change in the Th1-Th2 ratio toward Th2 was observed within the primary tumors expressing moderate to high levels of CCL2 and low to negative levels of CCL5. The CCL2-CCR2 interaction induced monocytes/macrophages to secrete the Th2-attracting chemokine CCL22 in vitro, suggesting that CCL2 secreted in the tumor microenvironment may attract and interact with monocytes/macrophages and favor Th2 T-cell accumulation by inducing CCL22 secretion.