Intercellular adhesion in vascular biology, thrombosis and cancer

Over the past 10 years or so, a considerable literature has focused on the circulatory and migratory properties of leucocytes, with regard to the immune system. It has become evident, however, that molecular events that regulate leucocyte interactions link the immune response to a number of 'non-immune' mechanisms, and it is now abundantly clear that a relatively small number of cell-surface receptors govern broad cellular functions. In particular, some families of molecules have been described which, although different in structure from each other, control in concert the adhesion of a cell to another cellular or extracellular ligand, and thus promote communication between intracellular signals and the extracellular environment. The present review outlines some aspects of the recent explosion in scientific knowledge in this field. Particular attention is centred on the intercellular receptors that modulate interactions between circulating blood cells and the vascular endothelium. Characteristically, these transmembrane glycoproteins have been grouped into families, based on biochemical homologies and molecular structure. Their discovery is challenging the commonly accepted view of medical practice, and their identification and characterisation are leading to significant advances in the diagnosis and therapy of a wide spectrum of human diseases. In the current overview, fundamental structural and functional relationships are summarised and prospects for future developments, especially with regard to laboratory diagnosis and patient management, are introduced. There can be little doubt that further advances in this field will have a major impact on biomedical and clinical sciences.