Cellular strategies in receptor-mediated phagocytosis.

Two strategies by which mononuclear phagocytes restrict and localize their microbicidal capacities are reviewed. The first concerns the ability of macrophages to seal off a closed compartment between themselves and opsonized targets. This compartment may be used to contain, concentrate, and protect toxic substances secreted by the phagocyte. The second concerns the ability of macrophages to regulate the phagocytosis-promoting capacity of their C3 receptors. C3 receptors are maintained in an inactive state, but they can be readily activated at sites of infection in such a way that they promote vigorous phagocytosis.