The mannose receptor of macrophages: a current perspective

Abstract

Specific recognition is a hallmark of modern immunology and no area of research activity has generated more enthusiasm than oligosaccharides as mediators of specific recognition. This interest has been nurtured by the belief that oligosaccharides will play some fundamental role in recognition and sorting both at the cellular and molecular level. Indeed, an extension of this view would point to an entirely new lexicon for biological communication, with the vocabulary built of monosaccharids units. However, as often happens with the teleological approach, extensive research has not turned up a vast new panaceae; rather, progress has been slow. On the plus side, however, several mammalian carbohydrate-specific recognition systems have now been delineated and studies on this small collection of receptors and their corresponding recognition determinates have yielded a vast amount of new information. To date, the focus of much work has been on the galactose receptor of hepatocytes (1), the mannose phosphate receptor of fibroblasts (2) and the mannose receptor of macrophages (3). Evidence has also been presented for a galactose-specific receptor in the macrophage (4). In addition, it is becoming increasingly clear that there exists a family of lectins which may be present in extracellular fluids (e.g., mannose binding protein), in membranes (e.g. fucose binding protein) or in cytosol (e.g., galactose binding protein). These soluble lectins may play important roles in host defense or in cell biology, but research on this area, as recently outlined by Barondes (5), is just now developing.