A monoclonal antibody (904) that binds to a leukocyte cell adhesion-promoting glycoprotein, (Mol; CD11b/CD18) was administered (1 mg/kg, iv.) to open chest anesthetized dogs 45 min after the induction of regional myocardial ischemia. Ischemia was produced by occluding the left circumflex coronary artery (LCX) for 90 min and then reperfusing for 6 h. There was no difference between control and antibody treated groups with respect to arterial blood pressure, heart rate, or LCX blood flow. Administration of antibody produced no observable effect on circulating neutrophil counts, suggesting that antibody-bound neutrophils were not cleared from the circulation. The mean size of myocardial infarct expressed as percentage of the area at risk of infarction that resulted was reduced by 46% with anti-Mol treatment (25.8±4.7%, n = 8) compared to control (47.6±5.7%, n = 8; P < 0.01). The area at risk of infarction was similar between groups. Circulating (serum) antibody excess was confirmed in all 8 anti-Mol treated dogs by immunofluorescence analysis. Analysis of ST segment elevation on the electrocardiogram as an indicator of the severity of ischemia suggests that the anti-Mol reduces infarct size independent of the severity of ischemia. An additional group of dogs (n = 5) was tested with a control monoclonal antibody of the same subtype (murine IgGI) and was found to produce no significant reduction in myocardial infarct size. Accumulation of neutrophils within the myocardium was significantly attenuated with 904 treatment when analyzed by histological methods. These data demonstrate that administration of anti-Mol monoclonal antibody after the induction of regional myocardial ischemia results in reduced myocardial reperfusion injury as measured by ultimate infarct size.

Despite standard aspirin and heparin therapy, leukocyte activation with platelet adherence occurs after coronary angioplasty. The magnitude of leukocyte activation and platelet adherence appears to be higher in patients experiencing late clinical events.

The prostacyclin analogue iloprost (ZK 36374) inhibits neutrophil activation in vitro, reduces neutrophil accumulation in inflammatory skin lesions, and reduces ultimate infarct size in an anesthetized open-chest canine model of regional ischemia and reperfusion. Iloprost (0.1-100 microM) inhibited the in vitro production of superoxide anion by canine neutrophils in a concentration-dependent manner. Iloprost (100 ng/kg/min i.v.) inhibited C5a-induced neutrophil migration into inflammatory skin lesions as assessed by the neutrophil-specific enzyme marker, myeloperoxidase. The myeloperoxidase activity determined 2 hours after the intradermal administration of C5a in each of the groups was control 13.3 +/- 1.8 units/g tissue (n = 12) and iloprost 6.5 +/- 0.9 units/g (n = 12), p less than 0.01. Iloprost was administered to anesthetized open-chest dogs (100 ng/kg/min) 10 minutes after left circumflex coronary artery (LCCA) occlusion and continued during the 90-minute occlusion period and the first 2 hours of reperfusion. Regional myocardial blood flow was similar between treatment groups at baseline, 5 minutes and 80 minutes after LCCA occlusion, and after 1 hour of reperfusion. Infarct size, assessed 6 hours after reperfusion, was reduced by iloprost treatment: 22.4 +/- 3.1% of the area at risk (n = 15) compared with 42.4 +/- 3.3% of control (n = 13), p less than 0.01. Iloprost treatment reduced the accumulation of neutrophils (measured by myeloperoxidase activity) in the ischemic myocardium at the interface between infarcted and noninfarcted tissue: control (n = 9) 9.0 +/- 1.8 units/g tissue, iloprost (n = 6) 2.0 +/- 0.4 units/g, p less than 0.01.(ABSTRACT TRUNCATED AT 250 WORDS)

We investigated the hypothesis that CD54 (intercellular adhesion molecule-1) expressed on hepatocytes will support beta2-integrin (CD18)-dependent adhesion of neutrophils. An in vitro model using C3A cells (a human hepatoblastoma cell line exhibiting many characteristics of normal hepatocytes) and human neutrophils was utilized. C3A cells were stimulated with interleukin-1beta (IL-1beta), tumor necrosis factor-alpha, or interferon-gamma (IFN-gamma) for 24 h to induce expression of CD54, and adhesion of neutrophils was found to be markedly increased. Detailed studies with IFN-gamma-stimulated (100 U/ml) C3A cells revealed that this adhesion involved CD11a/CD18 [lymphocyte function-associated antigen-1 (LFA-1)] and CD54 and was dependent on low levels of IL-8 produced by the stimulated hepatocytes. Addition of higher concentrations of chemotactic factor (e.g., IL-8) further augmented adhesion and recruited contributions of CD11b/CD18 (Mac-1). In contrast to LFA-1, Mac-1 appeared to recognize a CD54-independent ligand constitutively expressed on the hepatocytes. Such close apposition of neutrophils to hepatocytes may increase the potential for parenchymal cell injury by providing a short distance through which cytotoxic factors such as reactive oxygen or proteolytic enzymes could act.

In the present investigation electrolysis of a physiological buffer solution for 2 min with a constant current (20 mA, DC stainless steel anode) was observed to generate free radicals, determined by a luminol assay. Rabbit isolated hearts perfused with physiological buffer subjected to electrolysis were observed to undergo an increase in coronary artery perfusion pressure (PP) and in left ventricular end-diastolic pressure (LVEDP), 80 +/- 4 and 52 +/- 7 mmHg, respectively. Immediately after electrolysis of the physiological buffer, the hearts were observed to accumulate and retain (8-fold) more 125I-labeled albumin than hearts perfused with normal buffer without electrolysis, indicating an increased vascular permeability. The free radical scavengers, dimethyl sulfoxide (DMSO) and catalase (CAT), provided significant protection of the hearts against the changes in PP, LVEDP, and vascular permeability. This study demonstrates that toxic oxygen species generated independently of circulating blood elements or enzymatic reactions can have a direct effect on the vasculature of an isolated heart leading to alterations in cardiac function. The protection afforded by the addition of DMSO or CAT to the perfusion system would suggest that the OH. radical and H2O2 were the reactive oxygen species involved in producing the observed vascular and cardiac effects.