Characterization of a postlavage, in situ pulmonary macrophage population

Abstract

A postlavage in situ subpopulation of pulmonary macrophages (PM), biochemically distinct from the lavaged population, has recently been isolated from rats. After exhaustive bronchopulmonary lavage to extract the free lung cells, the lungs were excised, homogenized, and filtered, and the resultant cell suspension was allowed to form a monolayer on plastic Petri dishes. Electron microscopic morphometry failed to indicate any morphologic differences in the two populations. The postlavage in situ PM were more active metabolically during phagocytosis of zymosan particles or stimulation by phorbol myristate acetate (PMA) than the corresponding lavage population, as evidenced by greater superoxide generation. Macrophages prepared by either method became more avidly phagocytic when incubated with cell-free medium isolated in the preparation of the situ population. Peroxidase, an enzyme absent from the granules of PM separated by lavage techniques, was found in a granule-rich fraction of the in situ macrophage. Catalase activity was found in similar amounts in both supernatants and granule-rich fractions of both populations. The results support the concept of subpopulations of PM and suggest that these subpopulations are distinguished by their biochemical properties and their functional abilities.

Flow cytometric studies of equine phagocytes following strenuous exercise

“…Innate DCFH oxidation (without addition of an agonist) was significantly higher in macrophages than in granulocytes. These observations correlate with previous reports that alveolar macrophages have a higher resting production of oxygen radicals but a smaller respiratory burst compared to granulocytes (Orens et al 1963;Drath et al 1982). In this study, effects of xylazine and lignocaine cannot be excluded as a possible cause for the different responses of Macrophages were significantly more granular (P=0.016) at baseline 2 (212.4 * 11.6) compared to baseline one (146.8 f 10.2).…”

Enhanced superoxide release and tumoricidal activity by a postlavage, in situ pulmonary macrophage population in response to activation by Mycobacterium bovis BCG exposure

“…Pulmonary macrophage isolation. Alveolar macrophages were harvested as previously described (1). The separation procedure used for the postlavage in situ pulmonary macrophage population has been described in detail elsewhere (1).…”

“…Upon such exposure, the activated zymosantreated tissue macrophages released approximately twice as much superoxide as the nonactivated cells and amounts comparable to the amounts released by activated alveolar macrophages. The tissue macrophages also displayed greater levels of cytotoxicity toward xenogenic targets than the alveolar cells and may have an important role in preventing microbial or tumor cell colonization of respiratory systems.Recent information suggests that the monocytic phagocyte population of lungs is heterogeneous and may be characterized as comprised of either cells at different maturational stages or distinct subpopulations of phagocytes which may have arisen from separate stem cell progenitors (1,10,14,16). These cells may occupy the same lung compartment (i.e., the alveoli), be freely lavagable, and yet have distinct immunological, metabolic, and functional properties when they are isolated on Percoll gradients, or they may reside at separate geographic sites (i.e., the bronchi or lung parenchyma) and be separable only by mechanical or enzymatic tissue disruption (1, 7, 10).…”

“…Recent information suggests that the monocytic phagocyte population of lungs is heterogeneous and may be characterized as comprised of either cells at different maturational stages or distinct subpopulations of phagocytes which may have arisen from separate stem cell progenitors (1,10,14,16). These cells may occupy the same lung compartment (i.e., the alveoli), be freely lavagable, and yet have distinct immunological, metabolic, and functional properties when they are isolated on Percoll gradients, or they may reside at separate geographic sites (i.e., the bronchi or lung parenchyma) and be separable only by mechanical or enzymatic tissue disruption (1,7,10).…”

“…Recent information suggests that the monocytic phagocyte population of lungs is heterogeneous and may be characterized as comprised of either cells at different maturational stages or distinct subpopulations of phagocytes which may have arisen from separate stem cell progenitors (1,10,14,16). These cells may occupy the same lung compartment (i.e., the alveoli), be freely lavagable, and yet have distinct immunological, metabolic, and functional properties when they are isolated on Percoll gradients, or they may reside at separate geographic sites (i.e., the bronchi or lung parenchyma) and be separable only by mechanical or enzymatic tissue disruption (1,7,10). One such population of lung tissue-associated pulmonary macrophages which are capable of releasing greater quantities of superoxide upon stimulation, responding to endogenous factors with enhanced phagocytic avidity, and containing readily measurable quantities of peroxidase compared with freely lavagable alveolar macrophages has been described recently (1).…”