Human monocyte derived dendritic cells express functional P2X and P2Y receptors as well as ecto‐nucleotidases

Abstract

We investigated the expression and function of P2 receptors and ecto‐nucleotidases on human monocyte derived dendritic cells (DC). In addition we analyzed the effect of extracellular ATP on the maturation of DC. By RT‐PCR, DC were found to express mRNA for several P2X (P2X1, P2X4, P2X5, P2X7) and P2Y (P2Y1, P2Y2, P2Y4, P2Y5, P2Y6, P2Y10, P2Y11) receptors. As shown by FURA‐2 measurement, triggering of P2 receptors resulted in an increase in free intracellular Ca²⁺. In combination with Tumor necrosis factor‐α, ATP increased the expression of the DC surface markers CD80, CD83 and CD86 indicating a maturation promoting effect. DC expressed the ecto‐apyrase CD39 and the ecto‐5′‐nucleotidase CD73 as demonstrated by RT‐PCR. Extracellular ATP was rapidly hydrolyzed by these ecto‐enzymes as shown by separation of ³H‐labeled ATP metabolites using a thin layer technique. These data suggest that ATP acts as a costimulatory factor on DC maturation.