Ultrastructural analysis of pulmonary capillaries in the course of experimental lung emphysema.

Processes which occur within the capillaries of interalveolar septa play a major role in many lung diseases. In the present study, ultrastructural analysis of pulmonary capillaries was made at 7 days after intratracheal instillation of a proteolytic enzyme - papain, that is when macrophage cumulation within pulmonary tissue was maximal. Experimental animals (male Wistar rats) were injected with BCG vaccine, in doses that would stimulate the macrophage system to produce TNF-alpha. All the experimental groups, compared with the control, showed cumulation and increased adherence of monocytes, granulocytes and blood platelets to endothelium. Changes within endothelial cells manifesting their activation were observed. In the animals receiving papain or BCG, focal destruction of endothelial cells was found. The picture of vascular changes induced with papain and by simultaneous stimulation with BCG vaccine revealed a number of features similar to those found in the adult respiratory distress syndrome. The study proved usefulness of vascular perfusion as a method to analyze the vascular system, particularly in the processes progressing with activation and increased adhesion of inflammatory cells to the endothelium of pulmonary capillaries.