Ischemia Activates Neutrophils But Inhibits Their Local and Remote Diapedesis

摘要

Hindlimb ischemia and reperfusion results in local limb and distant lung injury. This study tests whether the mechanism of injury is by ischemia mediated polymorphonuclear leukocyte (PMN) activation and diapedesis. Anesthetized rabbits were subjected to three hours of hindlimb ischemia (n = 8) or sham ischemia (n = 4). PMN derived solely from the reperfused ischemic limb, assayed flow cytometrically displayed an oxidative burst of 135 +/- 8 fentamoles dichlorofluorescein (fmDCF)/cell compared to pre-ischemic levels of 74 +/- 14 fmDCF/cell (p<0.05). Additional aliquots of isolated neutrophils were treated with phorbol myristate acetate (PMA) 10(exp -7)M. In contrast to a 162% increase in oxidative burst prior to ischemia, neutrophils at 10 minutes of reperfusion had an enhanced response to PMA of 336% (p<0.05). Plasma collected from the ischemic hindlimb at 10 minutes of reperfusion when introduced into an abraded skin chamber or intratracheally induced diapedesis in non-ischemic animals. PMN accumulations in the+skin chamber were 1636 +/- 258 PMN/mm(exp 3) after 3 hours (n = 8) compared to 63 +/- 18 PMN/mm(exp 3) induced by sham plasma (n = 4, p<0. 05). Introduction of ischemic plasma intratracheally into a lobar bronchus (n = 4) induced PMN accumulations after 3 hours, measured by broncholveolar lavage fluid of 19 +/- 2 X 10(exp 4) PMN/mm(exp 3) compared to 5 +/- 1 X 10(exp 4) PMN/ mm(exp 3) with sham plasma (n = 4, p<0.05). Diapedesis was completely prevented (0-3 PMN/mm(exp 3), p<0.05) by introducing ischemic plasma into skin chambers in animals whose hindlimbs had been made ischemic (n = 6) or into chambers located on skin regions which had been previously made ischemic (n = 6). Similarly, following hindlimb ischemia, lavage of the lung with ischemic plasma yielded few PMN 0-3/mm(exp 3) (p<0.05).