INTERFERON y AND LIPOPOLYSACCHARIDE PROMOTE MACROPHAGE ADHERENCE TO BASEMENT MEMBRANE GLYCOPROTEINS

Although the ability of mononuclear phagocytes to interact with basement membranes and other extracellular matrices is well documented, the mechanisms involved and their possible modes of regulation are poorly understood (1) . Monocytes must penetrate the basement membranes of vascular endothelia during their emigration from blood to tissue (1) and they can encounter basement membranes again after they have differentiated into macrophages (e.g ., see reference 2) . Mononuclear phagocyte-basement membrane interactions are of considerable importance, for example, in chronic inflammatory disorders and the pathogenesis ofatherosclerosis (1) . However, the physiological and pathological factors that control mononuclear phagocyte interactions with the basement membrane have not been adequately defined, and the mechanism(s) used by these cells for diapedesis have not been rigorously explored . Macrophages do possess specific laminin-binding proteins (3, 4) and it seems likely that they also express collagen-binding proteins . How such surface proteins contribute to basement membrane interactions or how they might be regulated by factors that control the state of macrophage differentiation and activation are problems that have not been addressed . In this study, we analyzed the ability of thioglycollate (TG)-elicited mouse peritoneal macrophages, a population of recently extravasated monocytes, to interact with the basement membrane glycoproteins laminin and type IV collagen, as well as fibronectin, and we examined the effects ofmacrophage activation on these interactions .