Elevation of neutrophil chemotactic activity in the human serum and the decreased number of neutrophils after platelet-activating factor inhalation

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.