抄録
OS-3, a monoclonal antibody raised against macrophagic cells derived from cultured rat glomeruli, reacts with the plasma membrane of various bicarbonate-secreting cells such as epithelial cells of the pancreatic excretory duct and type B intercalated cells of the kindney, suggesting that the antigenic molecule of OS-3 is involved in bicarbonate production and/or secretion. Since osteoclasts must vigorously extrude bicarbonate to maintain cytoplasmic pH in a physiologic range during proton secretion, we examined the localization of OS-3 immunoreactivity in the bone tissue to determine the involvement of the detected molecule in the transmembrane transport of bicarbonate in osteoclasts. The OS-3 selectively stained the basolateral plasma membrane of osteoclasts. Ultrastructurally, the immunoreactivity with OS-3 was associated with small cytoplasmic projections and microplicae of the basolateral plasma membrane. This finding suggests that osteoclasts express the molecule common to bicarbonate-secreting cells to utilize it for bicarbonate transport during bone resorption.
