IMMUNOCYTOCHEMICAL ANALYSIS OF BAND-3 PROTEIN IN RENAL-CELL CARCINOMA, NEPHROBLASTOMA, AND ONCOCYTOMA

Band 3 protein is an anion-exchange protein that in the human kidney i s restricted to a subpopulation of collecting duct-intercalated cells; however, it is absent in the metanephric-derived cells of the nephron . We have studied band 3 protein expression in a series of 60 renal tu mors that included 10 oncocytomas, 42 renal cell carcinomas, and eight nephroblastomas by using frozen tumors and a monoclonal antibody. We detected band 3 protein expression in nine of 10 oncocytomas but not i n any renal cell carcinomas or nephroblastomas. This finding confirms that band 3 protein is a specific marker for oncocytoma and therefore may have a potential diagnostic application. It also supports the cont ention that renal cell carcinoma and oncocytoma are histogenically unr elated; the former is metanephric blastema derived and the latter is a mpullary bud derived.