Impact of leukocyte adhesion on myocardial ischemia/reperfusion injury: conceivable mechanisms and proven facts.

Leukocyte activation, adhesion, and emigration serve a protective role during a well-contained inflammatory response. However, under certain pathologic conditions such as endotoxemia, inflammatory bowel disease, and ischemia-reperfusion injury, leukocytes may turn against the host and aggravate--rather than prevent--tissue damage. Numerous experimental studies have been performed during the last decade to investigate the pathophysiologic role of leukocyte accumulation and adhesion during ischemia/reperfusion injury of various organs, in particular of the myocardium. Most of the latter studies investigated whether the consequences of experimental myocardial infarction could be attenuated by interventions aimed at the inhibition of chemotactic leukocyte infiltration or adhesion (or both) to microvascular endothelial cells. Although many promising results were reported, the consequent step towards an introduction of these strategies into experimental or even routine clinical management of patients with myocardial infarction has so far not been undertaken. In this manuscript, the authors try to give an overview on the state of the art of "antileukocyte" strategies in myocardial ischemia-reperfusion injury and to offer explanations for incongruent data obtained with diverse experimental approaches (animal species, treatment modalities, surgical and anesthesiologic artifacts, techniques for morphologic and functional evaluation of tissue damage). The authors conclude that long-term preclinical studies on suitable animal models, thoroughly investigating the positive and negative effects of antileukocyte interventions on the functional consequences of myocardial ischemia-reperfusion injury, are mandatory before the first clinical trial can be advocated.