Adenosine balance regulates the outcome of inflammation. Red and blue background colors represent low and high levels of extracellular adenosine, respectively. In normal situation (middle lane), inflammatory tissue damage following immune activation increases extracellular adenosine levels (red to blue). Adenosine-A2AR signaling controls tissue-damaging activities and inflammation resolves. When immune activation takes place in adenosine-enriched environment (right lane), effector functions of immune cells are insufficient to eliminate pathogens; therefore, it may result in outgrowth of infectious agents and tumor cells. Contrary to this, absence of adenosine-A2AR signaling (left lane) may cause uncontrolled immune activation, which may lead to tissue disfunction. It may be possible to intervene inflammatory responses by modifying the intensity of adenosine-A2AR signal.