An in vivo chemotaxis assay in the dog trachea: evidence for chemotactic activity of 8,15-diHETE

Abstract

We describe a new in vivo chemotaxis assay in the dog trachea using a double-balloon endotracheal catheter. When inflated, the two balloons isolate a segment of trachea, which is perfused through Silastic tubes using a peristaltic pump. After instilling a chemotactic agent, the perfusate is sampled periodically to permit characterization of the chemotactic response. We anesthetized four mongrel dogs and ventilated them mechanically through the double-balloon catheter. Two mediators, leukotriene B4 (LTB4) and 8S,15S-dihydroxyeicosatetraenoic acid (8,15-diHETE) were tested in each dog by perfusing the trachea with each mediator in Hanks' balanced salt solution (HBSS) containing ethanol and antibiotics. Aliquots were removed for differential cell counts at fixed time intervals over a 4-h period. Control experiments performed in each dog with the identical concentrations of ethanol and antibiotics in HBSS showed no cellular response before 180 min. At 240 min, the cell counts were 86 +/- 28 (SE) granulocytes/microliter (n = 4). In contrast, both LTB4 and 8,15-diHETE gave a significant cellular response at 120 min (309 +/- 125 and 141 +/- 41 granulocytes/microliter, respectively; P less than 0.05) but did not differ significantly from each other. These results suggest that both LTB4 and 8,15-diHETE can incite inflammatory responses in the dog trachea in vivo. Furthermore, the double-balloon catheter technique promises to be a useful in vivo chemotaxis assay.