Immunohistochemical localization of renin in renal tumors

Immunoperoxidase staining for renin was performed with renal tumors, including juxtaglomerular (JG) tumor, Wilms' tumors, renal adenocarcinomas, renal oncocytomas, and cortical adenomas. Compared with the JG apparatus adjacent to the glomerulus, JG tumor cells were less darkly but diffusely stained for renin. One of five Wilms' tumors revealed more numerous renin-containing tumor cells than the adjacent renal cortex, whereas three of ten renal adenocarcinomas and two of three renal oncocytomas revealed only focally renin-positive tumor cell cytoplasms. None of six cortical adenomas were positive for renin. With available fresh tumor tissue, renin activity was studied by measuring newly formed angiotensin I by radioimmunoassay. JG tumor contained markedly elevated renin activity, whereas one Wilms' tumor and two renal adenocarcinomas contained no more than 2% of renin activity of the renal cortex, more than 50% of which was inactive renin. These findings suggest that the JG tumor elaborates enormous amounts of active renin, whereas other renal tumors produce lesser amounts of renin, more than half of which is inactive renin.