Fig. 3.

ATP is an autocrine/paracrine factor for mast cells. ATP is released from mast cell granules and could induce activation of the same or neighbor mast cell via P2X and P2Y receptors. Simultaneously, ectonucleotidases, CD39 and CD73, catalyze the degradation of extracellular ATP to ADP and AMP and, subsequently, to adenosine. ADP and AMP could activate mast cell via P2X and P2Y receptors, while adenosine triggers P1 receptors