Reduced neutrophil infiltration protects against lung reperfusion injury after transplantation

Background. There is evidence that lung ischemia reperfusion injury is a re sult of the activation of components of the inflammatory cascade. However, the role of neutrophils in lung reperfusion injury continues to be a source of controversy. Methods. Using an isolated, whole blood-perfused, ventilated rabbit lung mo del, we sought to characterize the pattern of reperfusion injury and invest igate the contribution of neutrophils to this injury. Donor rabbits underwe nt lung harvest after pulmonary arterial prostoglandin E-1 injection and Eu ro-Collins preservation solution flush. Group I lungs (n = 8) were immediat ely reperfused without ischemic storage. Group II lungs (n = 8) were stored for 18 h at 4 degrees C before reperfusion. Group III lungs (n = 10) under went 18 h of ischemic storage and were reperfused with whole blood that was first passed through a leukocyte-depleting filter. All lungs were reperfus ed for 2 h. Results. Arterial oxygenation in group III progressively improved, and was significantly higher than that of group II after 2 h of reperfusion (272.58 +/- 58.97 vs 53.58 +/- 5.34 mm Hg p = 0.01). Both pulmonary artery pressur e and pulmonary vascular resistance were significantly reduced in group III when compared with group II (27.85 +/- 1.45 vs 44.15 +/- 4.77 mm Hg, p = 0 .002; and 30,867 +/- 2,323 vs 52,775 +/- 6,386 dynes.sec.cm(-5), p = 0.003, respectively). Microvascular permeability in group III lungs was reduced t o 73.98 +/- 6.15 compared with 117.16 +/- 12.78 ng Evans blue dp eg tissue in group II (p = 0.005). Group III myeloyeroxidase activity was 56.92 +/- 6 .31 Delta OD/g/min compared with 102.84 +/- 10.41 Delta 0d/g/min in group I I (p = 0.002). Conclusions. Leukocyte depletion of the blood reperfusate protects against microvascular permeability and significantly improves pulmonary graft funct ion. The neutrophil plays a major role in amplifying lung injury later duri ng reperfusion, and this lung ischemia reperfusion injury may be reversed t hrough the interruption of the inflammatory cascade and the interference wi th neutrophil infiltration. (Ann Thorac Surg 1999;67:1428-34) (C) 1999 by T he Society of Thoracic Surgeons.