The interaction of lipoproteins with endothelial receptors can result in alterations in macromolecular transport, in changes in monocyte adherence to the endothelium, and in the production of monocyte chemotactic factor by the endothelium. Monocyte migration in response to such factors can further alter lipoprotein transport into the subendothelial space, and all of these factors may play a role in the development of the atherosclerotic lesion.