[Macrophage scavenger receptors and the maintenance of blood vessels]

Recent molecular cloning of cDNAs for Macrophage Scavenger Receptors (MSR) reveal several unexpected features of these receptors. These MSRs mediate wide range of ligands, especially negatively charged macromolecules. Expression of MSRs are highly specific to macrophages. The intracellular pathways for endocytosis and recycling of MSRs are efficient only in macrophages. Immunocytochemical study of MSRs show that all of the tissue macrophages, including brain scavenger cells (FGP cells) are MSR positive. Under some pathological conditions, such as atherosclerotic lesions, macrophages infiltrating into these lesions, which are derived from monocytes, are also positive for MSR. Macrophages expressing MSR are thought to play an important role in the clearance and maintenance of blood vessels. Brain scavenger cells may play a role in the maintenance of small blood vessels in the brain.