Pulmonary intravascular sequestration of activated neutrophils: failure to induce light-microscopic evidence of lung injury in rabbits.

Rabbits were injected intravenously with glycogen-elicited allogenic peritoneal polymorphonuclear neutrophil leukocytes (PMNs) for the study of the light-microscopic effects of acute and chronic sequestration of PMNs in the pulmonary vascular bed. Infusion of 51Cr-labeled PMNs demonstrated that approximately half of the cells were sequestered in the lung, with no difference observed between PMNs incubated with 10% normal rabbit serum and PMNs incubated with 10% zymosan-activated serum (ZAS) prior to infusion. Quantitative histologic studies demonstrated that the number of ZAS-activated PMNs present in the alveolar walls at 4 hours rapidly declined over the ensuing 20 hours and was back to buffer control values by 48 hours. No PMNs, red cells, or signs of edema were visible in the alveolar spaces. In rabbits injected chronically (twice weekly for 8 weeks) with 2 x 10(8) PMNs (ZAS-stimulated and unstimulated), no qualitative or quantitative (mean linear intercept) evidence for damage to alveolar walls was observed. These studies indicate that acute and chronic pulmonary sequestration of PMNs activated in vitro, infused in the absence of activated serum products, does not cause light-microscopic evidence of lung injury.