Lung inflammation: The role of alveolar macrophages

Abstract

Free radical oxidation (FRO) processes has been suggested to be the leading mechanism in the pathogenesis of lung diseases. The aim was to study FRO processes in experimentally induced pneumonia (PN) Methods: PN was induced in 80 white rats by transthoracic injection of pneumococcus culture. The animals were sacrified before pneumococcus injection, and on the 1, 3, 7 days of PN. The content of malonic dialdehyde (MDA) was determined in the lung, liver and kidney tissues. The production of active oxygen forms (AOF) by alveolar macrophages (AM) was determined by nitroblue tetrazolium (NBT) test. Fe 2+ -induced chemiluminescence (ChL) of tissues and blood was recorded, morphological investigations were performed. Results: MDA content in the lung of intact animals was lower than in other tissues. In the presence of Fe 2+ in the lung tissue MDA value increased insignificantly and ChL was not observed. Addition of pulmonary homogenates to hepatic homogenate suppressed ChL and reduced MDA accumulation. On the 1-st day of PN in rats the content of MDA in the lungs, values of NBT-test of AM, ChL of blood have been increased. The NBT values of AM correlated directly with MDA content in lungs and ChL intensity of blood. On the 3, 7 days the level of MDA in the lungs remained high, NBT values of AM and ChL of blood were found to be increased, infiltration changes were abundant in the lungs of rats. Conclusion: The lung tissue has been found to possess high antioxidant activity. The development of PN is accompanied by the enhancement of FRO processes. AOF produced by AM initiated FRO in experimentally induced PN.