Purinoceptor function in the immune system

Abstract

Immune cells express plasma membrane receptors for extracellular adenosine and purine and pyrimidine nucleotides. Overwhelming evidence suggests that these receptors have a pivotal role in the modulation of several immune cell responses, and may therefore be very important in the overall economy of the immune network. Adenosine can be either an activatory or an inhibitory mediator. Nucleotides have a more complex effect, depending not only on the P2 receptor subtype activated but also on doses applied and the length of stimulation. Both metabotropic (G-protein-linked) and ionotropic (intrinsic ion channels) P2 receptors are present in immune cells and their expression is modulated by inflammatory cytokines and differentiation agents. The physiological meaning of the P2 receptors is still obscure; however, converging evidence from different laboratories suggest that they may be involved in a wide variety of responses such proliferation, differentiation, cell death, and cytokine release