THE EFFECT OF SIZE OF POLYSTYRENE PARTICLES ON THEIR RETENTION WITHIN THE RAT PERITONEAL COMPARTMENT, AND ON THEIR INTERACTION WITH RAT PERITONEAL-MACROPHAGES INVITRO

Polystyrene particles (size range 300nm-3μm diameter) were radioiodinated and their capture by rat peritoneal macrophages measured in vitro. For unmodified particles, most efficient accumulation was observed using a diameter of 600nm (Endocytic Index (E.I.) = 16.4 ± 2.9μl/106cells/h). Particles (3μm diameter) which had been modified to become more hydrophilic by hydroxymethylation showed an increased rate of capture (E.I. = 136.6 ± 91.2μl/106cells/h). Following intraperitoneal administration to rats, unmodified 3μm particles showed selective accumulation in the omentum (18.4% injected dose/g), and this was increased for the hydroxymethylated bead (35.3% dose/g). The smaller (800 nm) particles were better able to leave the peritoneal compartment. Radiolabelled particles isolated from a peritoneal wash after 5h were mostly cell-associated (72-86%, depending on the type of particle). © 1991.