Acute and Subacute Effects of Injury on the Canine Alveolar Septum: Results (7)

It appears that the mere presence of neutrophils in the lung does not produce emphysema. On the other hand, MacNee et al, recently reported that cigarette smoking was accompanied by retention of radioactively labelled neutrophils from the lungs of smokers who smoked during their study. Based on experimental studies showing margination of neutrophils preferentially in the alveolar vessels of rabbit lungs and on regional differences in neutrophil margination in dog lungs, they postulate that the lesions which characterize emphysema may be a result of destruction of lung tissue by neutrophils which remain within pulmonary microvessels. In an accompanying editorial, McGowan and Hunninghake pointed out that both neutrophils and macrophages may contribute to the production of emphysema. This may come about not only as a result of elastase production and antiprotease inhibition by macrophages, but also perhaps as importantly by the release of chemotactic factors which attract neutrophils to the site and by the secretion by macrophages of a peptide which releases neutrophil granule contents. buy ampicillin
It is enticing to speculate that alveolar macrophages attract neutrophils to alveolar junctional sites. Here a transient imbalance between proteases and antiproteases brought about by any of a number of mechanisms might result in favor of the former. This might in turn explain the preponderance of interstitial septal gaps at junctional sites and the influx of type 2 cells to these sites to repair them.