Influence of different P2Y receptor agonists on IFN-α production by PDCs. PDCs were stimulated with CpG ODN 2216 in the absence or presence of ATP, ADP, adenosine (ADO), the P2Y₁₁ receptor agonist AR-C67085, UTP, UDP-glucose, IDP, or UDP at the indicated concentrations (note: UDP concentrations differ from other nucleotides). IFN-α production in the absence of nucleotides was normalized to 100%. Data represent mean values (± SEM) of 5 to 10 donors.