Heterogeneity of procoagulant activity and cytokine release in subpopulations of alveolar macrophages and monocytes

We have studied the expression of tissue factor (TF) and fibrinopeptide A ( FPA) generation as well as the release capacity of TNF-alpha, IL-1 beta, an d IL-6 in density-defined subpopulations of alveolar macrophages (AM) and m onocytes (Mo). TF was equally expressed on all AM subpopulations and Mo, wh ile the FPA-forming capacity was at the same level in low density AM as in Mo and was significantly (P < 0.05) higher in low density AM than in high d ensity AM. The lipopolysaccharide (LPS)-induced release of TNF-alpha was hi gher (P < 0.05) in high density AM than in low density AM and in Mo. IL-1 b eta release was undetectable in unstimulated AM and in LPS-stimulated low d ensity AM, while the LPS-induced IL-1 beta release in high density AM was l ow compared to the levels demonstrated in Mo. LPS-stimulated IL-6 release w as not distinctively different in the AM subpopulations and Mo. The present ed study showed that FPA generation and LPS-stimulated TNF-alpha release we re dependent on the density (i.e., maturity) of AM. This implies that a ske wed distribution of AM subpopulations induced by disease processes may prof oundly influence the inflammatory reactions, including extravascular activa tion of coagulation.