Factors affecting neutrophil transit during acute pulmonary inflammation: minireview

Recent studies confirm data that for over a century have suggested that the lungs are an important source of noncirculating neutrophils. Many factors control how neutrophils pass through the normal lungs, including the unique and complex structure of the pulmonary capillary bed, local hemodynamic factors, neutrophil deformability, and neutrophil-endothelial interactions. Alterations in these factors are likely to influence neutrophil traffic in the lungs in disease processes where neutrophil-induced lung injury has been implicated. In recent years experimental approaches using in vitro techniques have been used to study neutrophil function. Such studies, together with in vivo studies in whole animals and to a limited extent in humans, will help to elucidate the important mechanisms in neutrophil sequestration in the acute and chronically inflamed lung. Novel avenues of therapeutic intervention in neutrophil traffic through the lungs may then be possible. However, whether interference with this cell, which forms a major defense mechanism in the lungs, is advisable, remains a matter for debate.