Eosinophil chemotactic activity of topical PAF on the human nasal mucosa.

Ten patients with strictly seasonal allergic rhinitis were challenged with 132 micrograms PAF-acether in each nasal cavity outside their relevant pollen season. Cells from the nasal mucosa were collected by nasal lavage prior to and every second hour up to 8 h after the PAF challenge. At the same times the volume of methacholine-induced secretory responsiveness was measured. A brush specimen was harvested from the nasal mucosa prior to and 8 h after the PAF challenge. PAF led to an increase in the number of eosinophils from an initial 6.1 to 64.4 per glass 2 h later. The number of eosinophils in the nasal lavage fluid then decreased to its initial baseline value. By 8 h after PAF challenge the number of eosinophils collected with the brush was still elevated as compared to the initial brush sample (3.1 vs 24.1). PAF did not produce any change in methacholine-induced secretory responsiveness at any time. It appears that PAF possesses eosinophil chemotactic properties in the human nasal airway without altering the nasal secretory responsiveness. This confirms previous findings that the induction of nasal responsiveness is a more complex phenomenon than just the recruitment of eosinophils into the airway mucosa.