PULMONARY RESPONSE TO BOVINE ALBUMIN - A MORPHOMETRIC STUDY IN RATS

The following hypothesis is proposed: that hypersensitivity pneumoniti s (HP), experimentally induced in rats, is the cause of a thickening i n the alveolar wall, a decrease in the size of the alveole, hyperplasi a in the bronchus-associated lymphoid tissue (BALT) and hypertrophy in the goblet cells. Wistar rats were classified into two different grou ps, namely, non-treated animals and animals exposed to bovine albumin (BA). A morphometric study was carried out and the following variables were quantified: a) percentage of lymphocytes, neutrophils and alveol ar macrophages of the bronchio-alveolar lavage (BAL); b) the interstic e of the alveole, the alveolar chord length, the alveolar wall thickne ss and the number of alveolar macrophages with hemosiderin within its cytoplasm; c) the size of lymphatic area (LA) in BALT, the length of t he lymphatic epithelium (LEp) in BALT and the percentage of goblet cel ls in the bronchial epithelium. The following results were obtained fr om the animals exposed to BA: 1) a significant increase in both lympho cytes and neutrophils of BAL, and of alveolar macrophages with hemosid erin in its cytoplasm; 2) a significant thickening of the alveolar wal ls and the BALT elements, which confirms the above mentioned hypothesi s; 3) a significant increase in the alveolar chord and a significant d ecrease in the number of goblet cells of the bronchus, which contradic ts the above mentioned hypothesis. The increase in alveolar macrophage s with hemosiderin is related to an increase in the capillary alveole permeability, which, together with the variations in the BAL formula, lead us to consider the existence of an inflammation in the interstiti al alveole; this interstitial alveole inflammation explains the alveol ar wall thickening and the BALT hypertrophy.