Platelet-activating factor inhibits ciliary beat frequency of human bronchial epithelial cells

The aim of our study was to investigate the effect of activating factor on human bronchial ciliary beat frequency (CBF) ex vivo. Brush biopsies were o btained from eight children (mean age 6.6 years) who underwent bronchoscopy for clinical reasons (i.e., foreign body aspiration, chronic cough, strido r). Immediate measurement of CBF by phase-contrast microscopy and photo-ele ctric technique was performed before further treatment, and then on three s ubsamples: after adding platelet-activating factor (PAF) (10(-5) M), after adding the inhibitor WEB 2086 (10(-4) M), and after adding both PAF and WEB 2086. Addition of 10(-5) M PAF reduced mean CBF by 2.1 Hz to 9.2 Hz (p < 0 .05). The inhibitory effect of PAF was completely reversed by the addition of the PAF-inhibitor WEB 2086, whereas WEB 2086 alone did nut significantly influence CBF. Optimum PAF concentration had been determined in previous d ose-response experiments. Our data indicates that PAF involved in airway in flammation contributes to a decrease in mucociliary clearance in humans.