Platelet-activating factor (PAF) is a family of acetylated phospholipids with potent proinflammatory activities including the chemotaxis of eosinophils. The present study was designed to microscopically characterize the recruitment of eosinophils into rabbit lungs at 3 1/2 hours following the intravenous infusion of PAF (1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphocholine) administered cither as a bolus injection (0.5 nmole/kg over 15 sec) or a continuous infusion (0.319 nmole/min for 120 min). Focal collections of eosinophils within the pulmonary parenchyma were morphometrically identified at all levels of the ainvays/vasculalure following both bolus and continuous PAF infusion. Tissue eosinophils were increased in lungs of animals challenged with PAF in comparison to that of animals infused with the PAF carrier. In every animal, PAF-induced eosinophil migration via large muscular arteries was more prevalent than via postcapillary venules (e.g., 346±52 vs 116±18 eosinophils/mm2 after a PAF bolus; mean±se, n=4). Interestingly, there were no significant differences in pulmonary eosinophil recruitment between the groups of animals receiving a bolus injection of PAF as compared to those where PAF was continuously infused (e.g, 346±52 vs 298±51 eosinophils/mm2, respectively, in lung tissue adjacent to large muscular arteries; n=4 animals/group). Thus, a brief intravascular exposure to PAF rapidly initiates the recruitment of eosinophils into rabbit lung. These in vivo observations support the hypothesis that PAF may Daiticioate in the accumulation of pulmonary eosinophils as occurs in various allergic and inflammatory diseases.
|Original language||English (US)|
|State||Published - Dec 1 1996|
ASJC Scopus subject areas
- Molecular Biology