Effects of various barriers on platelet-activating factor-induced neutrophil chemotaxis.

Platelet-activating factor (PAF)-induced neutrophil migration across endothelial and epithelial barriers is an important event in inflammation. We compared the effects of PAF on human neutrophil migration through filters alone, and human umbilical vein endothelial and Madin-Darby canine kidney epithelial cells cultured on these filters. We found that the amount of PAF-induced neutrophil migration was barrier dependent. At low PAF concentrations, neutrophil migration through filters exceeded migration measured through either cellular barrier. As PAF concentrations increased to greater than or equal to 1 mumol/L, neutrophil migration through human umbilical vein endothelial cells often equaled or exceeded migration measured through filters alone. In contrast, significant neutrophil migration through Madin-Darby canine kidney cells was not observed until PAF concentrations exceeded 50 mumol/L. Thus, the intensity of PAF-induced neutrophil inflammatory processes is, in part, dependent on the barrier through which the neutrophils must migrate.