Protease and antiprotease responses in lung and peripheral blood in experimental canine pneumococcal pneumonia

We studied the effects of pulmonary infection with type III pneumococcus in dogs on the degree of granulocyte elastase-like esterase activity and on the degree of antiproteases in peripheral blood and lung lavage fluid. In 9 infected dogs the peripheral blood granulocyte esterase activity increased from a preinfection level of 361.3 +/- 51 units/10(8) leukocytes to 593.8 +/- 80 units/10(8) leukocytes (mean +/- SE) 24 h after pneumonia had been induced (p less than .02). Parallel changes were measured in granulocytes obtained from bronchial lavage fluid. The antitrypsin activity and esterase inhibitory activity of peripheral blood increased by 15% after infection was induced. The esterase inhibitory activity of lung lavage fluid increased from a preinfection level of 776 +/- 160 units/mg of lavage protein to 1,390 +/- 200 units/mg of lavage protein (p less than .05). These findings indicate that whereas both circulating and lung lavage granulocytes contain increased concentrations of proteolytic activity during infection, serum antiproteases and, to a larger extent, lung antiproteases, also are increased.