Excessive inflammatory responses can be horribly destructive. Unsurprisingly, therefore, immune responses are dampened down and fine-tuned in a multitude of ways to minimize their damaging effects. Four articles in this issue provide examples of such immune regulation on four different levels. Wolfgang Junger (page 201) explains that cells take it upon themselves to control their behaviour to extracellular cues through autocrine feedback loops involving purinergic receptors. ATP or adenosine released by immune cells following stimulation feeds back on the cells through activating or suppressive purinergic receptors that fine-tune cell functions and activation
