PAF induces actin polymerization in both naïve and FPR1_des neutrophils.

Human neutrophils (naïve or FPR1_des) were activated with a receptor agonist or latrunculin A and the change in polymerized actin was determined att different time points (15 to 120 sec) after activation. Naïve neutrophils were activated by PAF (100 nM) or fMLF (0.1 nM) and FPR1_des neutrophils were reactivated by PAF (100 nM) or latrunculin A (200 ng/ml). The stimulation at indicated time points was terminated by adding ice cold paraformyldehyde (final concentration 2%) to the cells. The amount of polymerized actin was determined by flow cytometry after phalloidin staining and compared to the amount of actin at time zero before activation. The values are shown as mean ratio ± SEM; n = 3.