Stimulation of adenosine receptors hinders the differentiation of monocytes to macrophages, probably through cAMP accumulation (277). Moreover, by engaging A1R (278), A2AR (278–282), A3R (281, 283) or setting off Gαs-paired ARs (284), adenosine reduces the pro-inflammatory activity of macrophages by dampening their ability to produce IL-12 (279), TNFα (278–280, 282, 283), macrophage inflammatory protein-1α (MIP1α) (281), nitric oxide (278, 285) and superoxide (284). In addition, by triggering A2AR (282, 286, 287), A2BR (288, 289) or unidentified ARs, adenosine promotes an M2 polarization of macrophages by inducing upregulation of arginase-1 (288, 290), IL-10 (279, 286, 289) and VEGF production (282, 287).