FIGURE 4.

Lyso-PS drives engulfment of viable exudate neutrophils (neut) by macrophages early in inflammation. A, time course of total neutrophils and macrophages (Mac) after induction of zymosan peritonitis in WT mice. B, 6-h exudate neutrophils (5 × 10⁶) from CD45.2 WT and gp91^phox−/− mice were harvested, PBSE-labeled, pre-mixed with lyso-PS liposomes or not, and adoptively transferred into recipient CD45.1 wild type mice at 18 h into zymosan-induced peritonitis. After 4 h, peritoneal cells were collected by lavage, and MΦ of recipient mice defined as F4/80⁺/CD45.1⁺/Ly6G⁻ were analyzed for ingested PBSE⁺ exudate neutrophils. Shown are representative density plots from three independent experiments demonstrating recipient macrophages positive for PBSE following adoptive transfer of WT neutrophils pre-mixed or not with lyso-PS liposomes (middle row), and gp91^phox−/− neutrophils pre-mixed or not with lyso-PS liposomes (bottom row). Upper right, bar graph shows summated data of PSBE⁺ recipient macrophages under each condition. Ctr, control. C, phagocytic indices for these same harvests were determined by visual inspection of cytospins. Dashed lines in B and C represent the background phagocytosis in control wild type mice that received PBS alone (no neutrophils). n = 3; *, p < 0.05 compared with WT neutrophil control. Data represent mean ± S.E.