Renin in the human kidney. Immunohistochemical localization.

We have localized the enzyme renin (EC 3.4.99.19) in the normal adult human kidney by immunohistology. Serial paraffin sections of kidneys were incubated with renin antisera and then processed by the peroxidase-antiperoxidase method. Renin immunoreactivity was observed in the juxta-glomerular "epithelioid granular cells" (JEG-cells) in the wall of the afferent and rarely of the efferent vessel of the glomerulus. JEG-cells have long cytoplasmic processes penetrating between adjacent cells. This suggests a possible paracrine release of renin. Staining of various segments of the tubular system was shown to be artifactual. The kidney proteins recognized by our anti-human renin antisera had similar characteristics to renin when determined by a combination of gel-electrophoretic and immunologic techniques. Renin immunostaining in the juxtaglomerular apparatus of the human kidney is discrete and reflects the low amount of extractable renin.