[Trypsin-induced leukostasis: granulocyte migration in airspaces].

Injection of trypsin triggers the delayed appearance of a lung emphysema. Classically, emphysema is attributed to elastase, more particularly to leucocyte elastase. Indeed the acute phase of this experiment is characterized by a granulocyte sequestration within the lung microvessels in diverse species. We also found granulocytes within the terminal airspaces; this fact implies a granulocyte extravasation and directed migration. In order to evaluate this airspace invading by granulocytes during trypsin induced-vascular leucostasis, we washed the lung in cats since this species develop leucocytosis easily. One lobe only was washed for avoiding to harvest the cells present in the trachea and the main bronchi. This study was designed in several parts: (1) the lungs were washed in normal condition and several months later when trypsin was given; (2) in a kinetic experiment, 3 lavages were made consecutively a day either in normal condition or under trypsin treatment; (3) the lung was washed one day after trypsin administration. The granulocytes, and among them the neutrophils particularly, increased in number or in percentage transiently within the terminal airspaces under trypsin treatment; these granulocytes found within the airspaces are about 20% of the lung granulocytes.