Neutrophils are not necessary for ischemia-reperfusion lung injury

The role of neutrophils (PMNs) in ischemia-reperfusion injury after lung transplantation is unclear. If PMNs are involved in ischemia-reperfusion injury in the intact rat, then PMNs should sequester in the injured lung and PMN-depleted rats should develop less injury. Group A rats were treated with a rabbit anti-rat PMN antibody causing profound neutropenia (less than 100 PMNs/microL) and group B with control serum (greater than 2,000 PMNs/microL). Rats were anesthetized and left lung ischemia was sustained for 90 or 180 minutes by clamping the bronchus and the pulmonary artery and vein. Lung injury was quantified by the accumulation of radiolabeled (125I) albumin in ischemic left and nonischemic right lungs (cpm per gram of lung/cpm per gram of blood). Ischemia caused significant lung injury (p less than 0.05) in both PMN-depleted (albumin leak index: 90 min, 0.208; 180 min, 0.218) and nondepleted (90 min, 0.222; 180 min, 0.241) animals compared with nonischemic controls (depleted: 90 min, 0.050; 180 min, 0.100; nondepleted: 90 min, 0.063; 180 min, 0.101); microscopy also demonstrated lung injury. The injury was not associated with PMN sequestration as shown by light microscopy. Thus, we conclude that PMNs are not necessary for ischemia-reperfusion injury and PMN-depletion does not attenuate ischemia-reperfusion injury.