THE CONTRIBUTION OF TYPE-II PNEUMOCYTES AND ALVEOLAR MACROPHAGES TO FIBROPLASIA PROCESSES IN THE COURSE OF ENZYMATIC LUNG INJURY

The aim of the paper was to evaluate mutual relations in the system of alveolar macrophage (AM) type II pneumocyte (PII) - interstitium of a lveolar septa, in the course of experimental lung emphysema in rats su bjected to BCG vaccine effect. Administration of BCG vaccine resulted in the cumulation of AM within pulmonary alveoli. These cells exhibite d morphological features of increased activity. Intratracheal papain i njection induced intralobular emphysema changes, partly generalized, i n the animal lungs. The emphysematous changes, with domination of inte ralveolar septum atrophy, were accompanied by focal accumulation of co llagen and elastin. Fibroplasia processes were strongly pronounced in BCG- and papain-treated animals. The areas of connective tissue fibres cumulation revealed indistinctness of the boundary line between PII a nd the interstitium in some places. Anchorage of collagen fibres and m icrofibrillary structures were observed in the cytoplasm of PII. The m orphological examinations of AM - fibroblasts co-cultures as well as t he evaluation of the uptake of H-3-thymidine did not show any signific ant differences between respective co-cultures of fibroblasts and AM i solated both from the lungs of control and experimental animals (treat ed with BCG or papain, and BCG+papain). However, a significant growth was noted in H-3-thymidine uptake between fibroblast cultures realized with or without cells isolated from the lungs. The results obtained s uggest the possibility of active participation of PII and AM in fibrop lasia processes in the course of lung rebuilding after papain administ ration and in pathological states of the pulmonary tissue, particularl y when they are accompanied by increased activity of alveolar macropha ges. They also support the inflammatory-repair hypothesis in the devel opment of emphysematous changes.