Intercellular Calcium Signaling Induced by ATP Potentiates Macrophage Phagocytosis.

Extracellular ATP is a signaling molecule exploited by the immune cells for both autocrine regulation and paracrine communication. By performing live calcium imaging experiments, we show that triggered mouse macrophages are able to propagate calcium signals to resting bystander cells by releasing ATP. ATP-based intercellular communication is mediated by P2X4 and P2X7 receptors and is a feature of pro-inflammatory macrophages. In terms of functional significance, ATP signaling is required for efficient phagocytosis of pathogen-derived molecules and apoptotic cells and may represent a target for macrophage regulation by CD39-expressing cells. These results highlight a cell-to-cell communication mechanism tuning innate immunity.