Cyclic AMP Represents a Crucial Component of Treg Cell-Mediated Immune Regulation Extracellular Adenosine is Required to Limit a Potentially Self-Destructive Inflammatory Immune Response Inflammatory immune reactions are accompanied by the release of high amounts of ATP in the extracellular space where it is converted into AMP by CD39 and dephosphorylated to adenosine by CD73 (33). Adenosine has strong anti-inflammatory influence on immune cells preferentially by triggering A2A and A2B receptors leading to the generation of intracellular cAMP. Interestingly, the anti-inflammatory action of adenosine is exploited by tumors where adenosine was shown to accumulate, thereby preventing immunological tumor regression (34, 35). COMMENT: Lately, I've been thinking a lot about cyclic AMP and I'm curious about what one may accomplish by artificially increasing its amount. One can so do easily with forskolin so I have embarked on a trial to see what happens. There are some unwanted side effects associated with indiscriminate increases of cyclic AMP so it's not risk-free. In particular, increases in heart rate are not to my liking. On the other hand, I'm looking forward to reduction of mast cell activation as a nice side effect.