A rapid, quantitative method for measuring leukocyte adhesion to normal and balloon-injured arteries in vitro

Many of the currently available techniques for quantifying leukocyte adhesion require monolayers of cells and are therefore unsuitable for use in ex vivo arterial tissue. Here we describe a rapid method to measure adhesion of leukocytes to intact artery strips and to determine the effect of artery injury on adhesiveness of leukocytes with and without activation. Leukocytes were isolated from rabbit blood, labelled with 51Cr, and added to the luminal face of the left and right subclavian arteries derived from the same animal. In some experiments the endothelium was removed before addition of leukocytes and in another series of experiments the artery was injured by inflating a balloon catheter within the lumen in vitro before leukocyte addition. After washing, the adhesion of labelled leukocytes was quantified by gamma counting. To determine localization of the leukocytes, some arteries were fixed in situ and examined microscopically, with confirmation of leukocyte identification by enzyme cytochemistry. The adhesion of leukocytes increased progressively during 60 min and was inhibited by reducing the temperature to 4°C. Adhesion was increased by the nitric oxide synthase inhibitor l-NAME. Stretching the artery wall in vitro using a balloon catheter increased leukocyte adhesion within 1 h after injury. In contrast, this did not occur following simple arterial denudation. Histological examination of stained en face preparations and transverse sections of the subclavian arteries revealed loosely adherent granulocytic leukocytes on the endothelial surface. This technique is straightforward and allows accurate and rapid measurement of autologous leukocyte adhesion to normal and pathologically altered arteries ex vivo.