In vitro and in vivo phagocytosis of bacteria. (A-C) In vitro phagocytosis of Alexa 488–conjugated S aureus and E coli by human monocytes. (*P < .01, vs Basal, n = 6). PBMCs (2.0 × 10⁷/mL) in 150 μL were incubated in Na medium containing 0.5mM Ca²⁺ with 1mM ATP for 15 minutes, 0.3mM OxATP for 30 minutes, 20μM CytD for 30 minutes, 1μM KN-62 for 15 minutes followed by addition of 1mM ATP, or fixed with 2% paraformaldehyde. (D-F) In vivo phagocytosis of Alexa 488–conjugated E coli by peritoneal macrophages from wild-type and P2X₇-knockout C57BL/6 mice. Mice were injected intraperitoneally with 1 mL of PBS, 5mM ATP, or 0.6mM OxATP followed 30 minutes later by injection of E coli. The mice were killed after 60 minutes, and peritoneal exudates were collected. The fluorescence was measured immediately after the addition of trypan blue. *P < .01, vs wild-type PBS control group; n = 5 for wild-type and n = 3 for knockouts.