Pharmacologic properties of P(2Z)/P2X(7 )receptor characterized in murine dendritic cells: role on the induction of apoptosis.

In the immune system, extracellular adenosine 5'-triphosphate (ATP) mediates a variety of effects mainly through activation of a particular receptor subtype, the pore-forming P(2Z)/P2X(7) purinoceptor. This purinergic receptor has been described chiefly in cells of hemopoietic origin such as T cells, thymocytes, monocytes, macrophages, and phagocytic cells of thymic reticulum. In this study, we characterized the P(2Z)/P2X(7) purinoceptor and the ATP-mediated apoptosis in murine spleen-derived dendritic cells (DCs). Dye uptake and apoptosis were evaluated by flow cytometry. ATP-treated DCs were permeable to different low-molecular-weight fluorescent probes such as ethidium bromide, YO-PRO 1, and lucifer yellow. Such an effect was dose-dependent (EC(50): 721 micromol/L); mediated by the fully anionic agonist (ATP(4-)); and specifically stimulated by ATP, BzATP, and ATPgammaS. Additionally, an ATP-induced increase in intracellular calcium was detected by microfluorometry. Furthermore, ATP treatment induced a significant increase in apoptotic DCs (64. 46% +/- 3.8%) when compared with untreated control cells (34% +/- 5. 8%), as ascertained by the TdT-mediated dUTP nick end labeling technique. Both ATP-induced DC permeabilization and apoptosis were inhibited by oxidized ATP, a P(2Z)/P2X(7)-specific antagonist. In conclusion, we characterized the expression of the P(2Z)/P2X(7) purinoceptor in murine spleen-derived DCs and described its role on the induction of apoptosis.