Platelet-HMGB1 regulates neutrophil recruitment via modulation of PF4 release. (A-B) Peritoneal chemokine levels. Peritoneal lavage fluid was collected at 18 hours after CLP. Peritoneal (A) MCP-1 and (B) KC concentrations were measured by ELISA. Data are means ± SD from 8 mice per group from 2 separate experiments. (C) In vitro chemotactic assay. Isolated neutrophils were cocultured with platelets in presence of indicated treatment of 1 hour. Data represent mean ± SD from 2 individual experiments. (D-E) Peritoneal (D) PF4 and (E) RANTES concentrations were measured by ELISA. Data are means ± SD from 8 mice per group from 2 separate experiments. (F-G) Isolated platelets from HMGB1 Flox, and HMGB1 PF4 mice were stimulated with or without thrombin (0.2 U/mL) for 2 hours. The concentrations of (F) PF4 and (G) RANTES in media in resting and stimulated conditions were measured using ELISA. These experiments have been repeated for 2 times. Data represent mean ± SD. Statistical difference was tested using Student t test; *P < .05.