Neutrophil retention during a single transit through the pulmonary circulation

Our laboratory has previously reported that 70–80% of polymorphonuclear cells (PMNs) are delayed with respect to erythrocytes (RBCs) in a single pass through the lungs of dogs, whereas only 5–15% of PMNs are delayed in a single pass through human lungs. Because these results were obtained using a direct blood sampling method in animals and an indirect gamma camera method in humans, the reported differences could be related to differences in measurement technique. The present study was designed to settle this question by comparing both techniques in a single species. The results show that the gamma camera technique previously used in humans underestimates the retention of PMNs with respect to RBCs during a single pass through the lung. They also show that this problem can be corrected by modifying the analysis of the data obtained using the gamma camera. We conclude that the pulmonary circulation retains PMNs with respect to RBCs to a comparable degree in animals and humans.