Protein Phenotypes of Mouse Macrophages Activated In Vivo for Tumor Cell Killing

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Abstract
We have shown previously that the cellular proteins 47b and 71/73 could be used to construct phenotypes that distinguish among bone marrow culture-derived (BMCD) macrophages that were either unstimulated or primed by gamma interferon or fully activated for tumor cell killing by gamma interferon in combination with lipopolysaccha-ride (LPS). In the present study we examined in vivo-derived correlates for each of these stages of macrophage activation and found that the same protein phenotypes held true: both p47b and p71/73 were expressed by cytolytic peritoneal macrophages, including macrophages from a tumoral effusion, whereas macrophages primed in vivo by the intraperitoneal injection of either concanavalin A or methyl vinyl ether copolymer II expressed p47b but lacked p71/73. Neither resident nor inflammatory macrophage populations expressed p47b, and acute inflammatory macrophages, like unstimulated BMCD macrophages, expressed little or no p71/73. By contrast, resident and thioglycollate-elicited macrophages synthesized moderate levels of p71/73. When p71/73 also was expressed, there was a quantitative relationship between p47b expression and cytolytic activity in five different in vivo-activated macrophage populations. The results suggest that, regardless of the macrophage source or stimulus, it may be possible to assess macrophage activation status by reference to protein phenotypes utilizing p47b and p71/73.