A new stimulation of the interaction between neutrophils and pulmonary endothelial cells

To study the interaction between isolated homologous neutrophils and pulmonary endothelial cells under simulated in vivo conditions, we developed a model of the circulation in which neutrophils flow past endothelial cells. Endothelial cells from porcine pulmonary artery were grown on microcarriers, loaded into an elutriator chamber, and suspended (speed--300 rpm. flow--18 ml/min). Porcine neutrophils were labeled with 111In, mixed with a tracer dose of 125I-albumin, and injected into the elutriator inlet. Fractions were collected from the elutriator outlet and indicator dilution curves were plotted. Adherence of neutrophils was calculated by 1 - (area under 111In curve/area under 125I curve). In separate injections, neutrophils were preactivated with phorbol 12-myristate 13-acetate (100 ng/ml) or zymosan-activated plasma (10%, v/v). In three of eight lines of endothelial cells the adherence of activated neutrophils to cell-coated microcarriers was greater than that of nonactivated neutrophils. There was no difference in adherence to uncoated microcarriers or to the empty elutriator chamber between activated and nonactivated neutrophils. We conclude that this model will be useful for studying interactions between isolated neutrophils and endothelial cells because it incorporates flow in a physiologic milieu.