Immunohistochemical localization of renin in the human kidney.

By using an antiserum to purified human renal renin, renin was localized immunocytochemically in the human kidney under normal and various pathological conditions by the unlabeled antibody enzyme light microscope: (LM) and protein A-gold colloid electron microscope (EM) procedures. In the normal kidney, renin was confined to the epithelioid cells of the afferent arteriole of the juxtaglomerular apparatus (JGA). These cells were small and few, and always in the immediate neighborhood of the glomerulus. Fine structural analysis showed renin only in the secretion granules of the epitheloid cells. All granules within a given cell were stained with comparable intensity. In cases of renal artery stenosis (ischemic kidney) and of Bartter's syndrome, renin-positive epithelioid cells were larger, showed increased staining intensity, and were often found along the afferent arteriole at some distance from the glomerulus. Again, by electron microscopic observation, renin was seen only in secretion granules of epithelioid cells. In all of the above pathologic cases, plasma renin activity was very high. However, in the other nephropathies studied, renin staining in the kidney resembled that seen in normal kidneys, even when levels of plasma renin activity were quite high.