P2X7-stimulated phosphatidylserine (PS) exposure on lymphocytes. P2X7-dependent exposure of PS on New Zealand Black (NZB) lymphocytes, New Zealand White (NZW) lymphocytes and (NZB × NZW)F1 (NZB/W) lymphocytes. To enable the direct comparison of responses of cells from NZB mice, NZW mice and (NZB × NZW)F1 mice in a single tube, lymphocytes from these strains were stained with anti-CD4CYCHROME, anti-CD4PE and anti-CD4APC, respectively, mixed and equilibrated with annexin VFITC. Thus labelled, cells could subsequently be distinguished by flow cytometric gating. Cells were stimulated with the P2X7 agonist 2'-3'-O-(4-benzoylbenzoyl)-adenosine 5'-triphosphate (BzATP) at the time indicated by the arrow in (a). (a) Density plots of the rate of extracellular PS exposure in each cell population, as indicated by increased binding of annexin VFITC. (b) Corresponding percentage of cells bearing exposed PS in each population at a single timepoint (indicated by boxes in (a)).