The role of leukocyte depletion by in vivo use of leukocyte filter in lung preservation after warm ischemia

The oxygen metabolites of leukocytes have been implicated as playing the central role in reperfusion injury of preserved lung for transplantation. Furthermore, it is still unknown how leukotrienes take part in this process. Twelve mongrel dogs were used, divided into two groups. In group A, left thoracotomy and hilar stripping of the left lung was performed under anesthesia. During warm ischemia (two hours) and reperfusion (two hours), a filter was used three times between the femoral artery and vein, and quantitative in vivo blood filtration was performed. In group B, warm ischemia and reperfusion was done in the same fashion without filtration. As for tissue free radical assay, lipid peroxidation products were measured by means of thiobarbituric acid. Tissue leukotriene B4 and C4 levels were measured by radio immunoassay. In addition, peripheral blood count and tissue wet/dry ratio were analyzed. Significant leukocyte depletion of peripheral blood with leukocyte efflux from reperfused lung was observed in group A. Significant increase of tissue malondialdehyde (MDA) titers after reperfusion was observed in group B, whereas no significant fluctuation of tissue MDA titers was noted in group A. Concerning leukotriene B4 and C4, no significant increase was observed in either group. Tissue damage estimated by lung wet/dry ratio was considered to be controlled in group A compared with group B. Thus, the authors conclude that in vivo use of a leukocyte filter is efficient in removal of peripheral blood leukocytes and in preservation of reperfused lung after warm ischemia and that oxygen metabolites of leukocytes are considered to play a role in tissue damage in this process.