Expression and a role of functionally coupled P2Y receptors in human dendritic cells

We investigated the physiology and function of P2Y receptors expressed in h uman dendritic cells (DCs) differentiated in vitro from CD14(+) cells (DC-1 4). These were obtained after a 10 day stimulation period in GM-CSF, IL-4 a nd monocyte conditioned medium. DC-14 were found to express high amounts of MHC class II, B7, CD40 as well as CD83. The functional analysis, using sin gle cell Ca2+ imaging, demonstrated the expression of at least three subtyp es of P2Y receptors. We further found using patch-clamp measurements that A TP evoked a pertussis toxin insensitive non-selective cation current with a peak current amplitude of -276 +/- 43 pA (holding potential -80 mV, n = 23 ). This current was not Ca2+-activated, since it was still observed under c onditions of high intracellular Ca2+ buffering and could be blocked by Gd3 (0.5 mM). In addition, intracellular application of GTP-gamma-S (0.3 mM) a lso activated the current. Interestingly, DC-14 redirected the orientation of their dendrites as well as cell shape towards a pipette containing ATP a s observed with time lapse microscopy. These data suggest that in human DCs , ATP acts via P2Y receptors and induces chemokine effects. (C) 1999 Federa tion of European Biochemical Societies.