ATP receptors and giant cell formation

We have investigated the role of the purinergic P2X 7 receptor in the formation of multinucleated giant cells in human monocyte/macrophage cultures stimulated with either concanavalin A or phytohemagglutinin. Macrophage fusion can be blocked by a P2X 7 ‐selective pharmacological antagonist or by a mAb directed against the extracellular P2X 7 domain. Furthermore, macrophage cell clones expressing high P2X 7 levels spontaneously fuse in culture, whereas macrophage clones lacking P2X 7 are unable to fuse. Our findings suggest that the newly identified purinergic P2X 7 receptor plays a central role in the complex chain of events leading to generation of macrophage‐derived giant cells. J. Leukoc. Biol. 66: 723–726; 1999.