Effect of Pluronic F68 and phospholipids liposomes modified with Pluronic F68 on the human neutrophils functional activity.

The sizes of Pluronic F68 micelles in water and phosphate-buffered saline (pH 7.4) were determined using dynamic light scattering. Micelles formation was observed at Pluronic F68 concentrations of 0.7 wt % and higher, with particle sizes not exceeding 5 nm. Fluorescence analysis using Nile Red indicated that the critical micelle concentration of Pluronic F68 in both water and phosphate-buffered saline is approximately 0.5 wt %. A luminol-dependent chemiluminescence assay demonstrated that Pluronic F68 at concentrations ranging from 0.01 to 0.5 wt % did not affect the spontaneous (non-activated) respiratory burst of human neutrophils. However, at 0.5 wt %, Pluronic F68 significantly inhibited the respiratory burst induced by latex particles. The modified with 0.05 wt % Pluronic F68 and not modified liposomes were obtained from phospholipids S75 via thin lipid film hydration and US-disintegration. The liposomes modified with Pluronic F68 also suppressed the neutrophil latex-induced oxidative response. The interaction of neutrophils with liposomes labelled with BODIPY dyes (λex/λem = 575/605 nm and 480/510 nm) was evaluated using flow cytometry and confocal fluorescence microscopy. Both types of liposomes -with and without Pluronic F68 - were internalized by neutrophils. Flow cytometry revealed that liposomes containing Pluronic F68 interacted with neutrophils 25 ± 7.8 % more efficiently than unmodified liposomes. Confocal microscopy with Z-stack imaging confirmed the intracellular localization of both types of fluorescent liposomes, with no evidence of their surface binding. These findings suggest that Pluronic F68 influences neutrophil function in its various forms: as monomers, micelles, and as a component of liposomal formulations. Notably, its inclusion in liposomes enhances cellular uptake.