Immunoreactivity of vacuolar H⁺-ATPase in human tissues - Using polyclonal rabbit antibodies against V-ATPase subunits

We immunohistochemically examined tissue distribution and cellular localization of vacuolar H⁺-ATPase (V-ATPase), which is a proton-translocating ATPase known as an acidifier of cytoplasmic vesicles and vacuoles, using two polyclonal rabbit antibodies against A and B subunits of the V-ATPase purified from bovine chromaffin granules. The intense staining was found in epithelial cells of the renal tubules and the salivary ducts, pancreatic a cells, endocrine cells in colon, macrophages, osteoclasts, and chondrocytes in human tissues, and the following three localization patterns of V-ATPase were found in the examined cells: 1) cytoplasmic pattern with granular and diffuse types, 2) polarized pattern, and 3) diffuse apical cytoplasm pattern. The granular type of cytoplasmic pattern was typically observed with high density in macrophages, a cells of the pancreatic islets and endocrine cells in colon. The diffuse type was often seen in most of ductal cells of exocrine glands, osteoclasts, nerve cells with moderate density, and in chondrocytes with high density, and the polarized pattern was represented by intercalated cells of the renal tubules with high density. The diffuse apical cytoplasm pattern was typically found along the brush border of proximal tubules from moderate to high density.