Purinergic P2X7 receptors are ATP-gated nonselective cation channels expressed in many cell types of the immune and inflammatory system. In macrophages P2X7 receptors are assumed to be involved in killing of intracellular bacteria. Frequently, P2X and P2Y receptors are coexpressed in immune- competent cells complicating the investigation of immunological functions mediated by P2X7 receptors. Here we demonstrate that in the mouse macrophage cell line RAW 264.7 the purinergic receptor P2X7 is the only P2X receptor which is functionally expressed beside P2Y receptors. This was done by measuring the effect of different known P2 receptor agonists and antagonists on whole cell membrane currents and [Ca^2+]_i signals. The results correspond to those found in human B lymphocytes in which also P2X7 receptors are the only functional purinergic P2 receptors beside the nonfunctional P2X1 and P2X4 whose messages were found. Therefore, the mouse RAW 264.7 cell line may serve as a model to investigate the role of P2X7 receptors in macrophages.

M Reiss, M Kuehnel and G Griffiths are members of the Cell

Biology Program, EMBL, Heidelberg