Nasal neutrophilia and eosinophilia induced by challenge with platelet activating factor.

Background: It has been demonstrated that in vitro platelet activating factor-acether (1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphorylcholine; PAF) has the capacity to attract eosinophils and neutrophils. We investigated whether the same applies when human nasal airways are stimulated with PAF.

Methods: Symptom scores and cytologic changes in nasal lavage fluids were evaluated in 10 atopic and 10 nonatopic subjects after nasal challenge with PAF, its precursor and metabolite, 1-O-hexadecyl-sn-glycero-3-phosphorylcholine (lyso-PAF), or saline solution.

Results: Nasal obstruction was reported by all the atopic subjects and seven of the 10 nonatopic subjects after nasal challenge with PAF; other symptoms such as rhinorrhea, itching, and sneezing were generally mild. PAF induced neutrophilia, which appeared after 30 minutes in atopic subjects and after 1 hour in nonatopic subjects, and peaked at 3 hours in both. Less neutrophilia was found 3 hours after stimulation with lyso-PAF in both groups of subjects. PAF also induced eosinophilia, which appeared after 30 minutes in atopic subjects and only after 3 hours in nonatopic subjects. An increase in eosinophil counts was observed 3 hours after lyso-PAF stimulation in atopic but not in nonatopic subjects.

Conclusion: PAF can attract neutrophils and eosinophils into human nasal airways; however, the recruitment of inflammatory cells is more rapid in atopic than in nonatopic subjects, suggesting a different degree of responsiveness to PAF challenge in the two groups of subjects.