The demonstration that hyaluronic acid specifically aggregates macrophages, but not other leukocytes or lymphocytes and that this proteoglycan is secreted into airways of man or animals suggests that this proteoglycan is a major effector molecule concerned with macrophage functions. Our current efforts are directed at exploring the role of various proteoglycans on alveolar macrophage functions, e.g., aggregation, migration, lysosomal secretion, prostaglandin production, adenyl cyclase activation, H2O2 secretion, phagocytosis, etc. Change in binding affinity, as well as rates of hydrolysis of the proteglycan will be assessed. Our other major effort is to understand the role of Na ion and H2O flux in leukocyte motility. Our current data strongly suggest that the local influx of Na ion is the specific signal for motility. Since the only enzyme inside these cells which is specific for Na ion is the Na ion ATP'ase which is located on the inside of the plasma membrane, along with the actin-binding protein and myosin, we suspect that interactions between these above three proteins, and actin, and Na ion and H2O is the crucial event in motility. The interactions between these 4 isolated proteins as well as their interactions is isolated plasma membrane, i.e., podosomes are under study.