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.