Suzuki M, Asako H, Kubes P, Jennings S, Grisham M B, Granger D N
Department of Physiology, Louisiana State University Medical Center, Shreveport 71130-3932.
Microvasc Res. 1991 Sep;42(2):125-38. doi: 10.1016/0026-2862(91)90081-l.
The objective of this study was to determine whether hydrogen peroxide (H2O2), hypochlorous acid (HOCl), and monochloramine (NH2Cl), at concentrations produced by activated neutrophils, promote leukocyte adherence to microvascular endothelium in post-capillary venules. Cat mesenteric venules (30-45 microns diameter) were examined using intravital video microscopy. Red blood cell velocity (VRBC), venular diameter (DV), and the number of adherent leukocytes (NWBC) were measured in postcapillary venules. Venular blood flow and wall shear rate (tau) were calculated from the measured values of VRBC and DV. Different concentrations (0.01-1.0 mM) of H2O2, HOCl, or NH2Cl were superfused on the mesentery. In some experiments, the contributions of the leukocyte adhesive glycoprotein CD11/CD18 and platelet-activating factor (PAF) in the oxidant-induced leukocyte adherence were determined using a CD18-specific antibody (IB4) and a PAF-receptor antagonist (WEB 2086), respectively. The results of our in vivo experiments indicate that H2O2 and NH2Cl, but not HOCl, promote leukocyte adhesion to venular endothelium. Incubation of isolated cat neutrophils with either NH2Cl or H2O2 resulted in activation of CD11/CD18, as assessed by flow cytometry. Although the leukocyte adhesion induced by both H2O2 and NH2Cl was associated with a reduction in venular wall shear rate, corresponding decrements in shear rate induced by partial occlusion of the mesenteric artery did not lead to similar levels of leukocyte adherence. The leukocyte adherence induced by H2O2 and NH2Cl was largely prevented by monoclonal antibody IB4, indicating that both oxidants promote leukocyte adherence via activation of CD11/CD18. The H2O2-induced, CD18-mediated leukocyte adherence appears to be elicited by PAF and by a direct effect of the oxidant on CD11/CD18 expression. The mechanism underlying the NH2Cl-induced leukocyte adherence remain unclear.
本研究的目的是确定活化的中性粒细胞产生的过氧化氢（H2O2）、次氯酸（HOCl）和一氯胺（NH2Cl）在相应浓度下是否会促进白细胞黏附于毛细血管后微静脉的微血管内皮。使用活体视频显微镜检查猫的肠系膜微静脉（直径30 - 45微米）。测量毛细血管后微静脉中的红细胞速度（VRBC）、微静脉直径（DV）和黏附白细胞数量（NWBC）。根据VRBC和DV的测量值计算微静脉血流和壁剪切率（tau）。将不同浓度（0.01 - 1.0 mM）的H2O2、HOCl或NH2Cl灌注到肠系膜上。在一些实验中，分别使用CD18特异性抗体（IB4）和血小板活化因子（PAF）受体拮抗剂（WEB 2086）来确定白细胞黏附糖蛋白CD11/CD18和血小板活化因子（PAF）在氧化剂诱导的白细胞黏附中的作用。我们的体内实验结果表明，H2O2和NH2Cl可促进白细胞黏附于微静脉内皮，而HOCl则无此作用。通过流式细胞术评估，用NH2Cl或H2O2孵育分离的猫中性粒细胞会导致CD11/CD18活化。虽然H2O2和NH2Cl诱导的白细胞黏附都与微静脉壁剪切率降低有关，但肠系膜动脉部分闭塞引起的剪切率相应降低并未导致类似水平的白细胞黏附。H2O2和NH2Cl诱导的白细胞黏附在很大程度上被单克隆抗体IB4阻止，这表明两种氧化剂均通过激活CD11/CD18促进白细胞黏附。H2O2诱导的、CD18介导的白细胞黏附似乎是由PAF以及氧化剂对CD11/CD18表达的直接作用引起的。NH2Cl诱导白细胞黏附的潜在机制仍不清楚。
