Elevation of Neutrophil Chemotactic Activity in the Human Serum and the Decreased Number of Neutrophils after Platelet-Activating Factor Inhalation

Abstract

We previously reported a significant decrease in neutrophils at 5 min and an increased number of neutrophils at 15 min after PAF-acether inhalation. To investigate the mechanism, we measured the neutrophil chemotactic activity of the sera. Neutrophil chemotactic activity (NCA) of the serum at 5 min was greater than at baseline (p < 0.01) or at 15 min (p < 0.05). Furthermore, we investigated the correlation between the change in NCA and decreased number of neutrophils. A significant correlation was found between these two at 5 min (r = 0.751 p < 0.05). These data suggest that an elevation of NCA may play an important role in the decrease of circulating neutrophils after PAF-acether inhalation.

Effect of Terfenadine on Neutrophil and Eosinophil Chemotactic Activities after Inhalation of Platelet-Activating Factor in vivo and on Neutrophil Chemotaxis in vitro

“…We hypothesize that the PAF-induced rise in NCA causes a brief decrease in the number of blood neutrophils [7]. Our current results show a discrepancy between the previously reported neu tropenia [17] and the NCA elevation.…”

“…Other investigators [4,5] have reported that PAF increases nonspecific bronchial hyperresponsiveness in humans; however, we could not verify that observation [6], PAF inhalation has been re ported to cause an elevation in neutrophil chemotactic ac tivity in the human serum and to transiently decrease cir culating neutrophils [7], It has been reported that chlorpheniramine, a hista mine antagonist, could inhibit the systemic and partially attenuate the airway response to inhaled PAF [8,9], Terfe nadine is a nonsedative histamine receptor antagonist [10,11]. We have shown the effectiveness of terfenadine in at tenuating the bronchospasm provoked by ultrasonically nebulized distilled water [12] and hyperventilation of cold air [13] in asthmatic subjects.…”

“…We have previously reported that PAF inhalation in duces an elevation of NCA in human serum and a transi tory decrease in the number of circulating neutrophils [7], In this study we also investigated the ex vivo effect of terfe nadine or placebo on changes in serum NCA and ECA fol lowing PAF inhalation.…”

“…For measurement of NCA, sera were incubated at 56 °C for 30 min. NCA and ECA of the sera were evaluated by using a modified Boyden chamber method, as described previously [7,19]. Briefly, 200 pi of serum from each subject was placed in the lower compartment o f the chamber.…”

“…The mechanism of NCA release after PAF challenge is not clear [7], Driver et al [25] have reported an elevation of NCA after bronchial challenge with adenosine and speculated that it is a high molecular NCA released from mast cells. As the time of elevation of NCA 5 min after PAF challenge resembles that after adenosine challenge [25], it is possible that the elevation of NCA after PAF challenge is dependent on mast cells.…”