Phenotypic and functional differences between rat alveolar, pleural, and peritoneal macrophages

Tissue macrophages (M Phi )play a central and essential role in modulating the initiation and Perpetuation of the inflammatory response. Phenotypical and functional differences among alveolar M Phi, (AM) and peritoneal M Phi (PM) have been reported, but less is known about pleural M Phi (PLM) and th eir ability and capacity to release biologically active substances. Therefo re, the aim of this study was to determine the production of superoxide ani on, nitric oxide (NO), and tumor necrosis factor alpha (TNF-alpha) by PLM i n comparison to AM and PM in vitro. M Phi from rats were isolated bg lavage of the respective body compartment and characterized by evaluating the exp ression of the surface antigens MHC class II molecules, CD11b, and ED2-like antigen. Upon activation, AM produced significantly higher amounts of supe roxide anion, NO, and TNF-alpha compared to PM and PLM Taken together, the findings of this study demonstrate that rat PLM resemble PM more than, AM i n terms of production of hey inflammatory mediators.