The significance of lectin receptors in the kidney and in hypernephroma (renal adenocarcinoma).

Normal kidney tissue as well as hypernephromas were examined histochemically for the occurrence of lectin receptors. FITC- and rhodamine-labeled peanut agglutinin (PNA) and Ricinus communis agglutinin (RCA) were used for labeling different carbohydrate residues which may be of interest in the evaluation of the histogenesis of hypernephromas and possibly for concepts regarding the immunotherapy of these tumors. By using fluorescence microscopy, the receptor for PNA was found on the epithelial cells of the thin limb, distal convoluted tubules, and the collecting ducts. These binding sites occurred in a free as well as in a sialic-acid-substituted form and were mainly exposed on the luminal surface of the epithelial cells. They were absent, however, in the proximal convoluted tubules. This finding contrasts with the demonstration of RCA receptors in the brush border of these tubules. Moreover, RCA reacted with the epithelial cells of all tubules. The hypernephromas showed a wide range in the distribution and the quality of the lectin receptors, which were localized within the cytoplasm as well as in the cell membrane of the tumor cells. As demonstrated by our histochemical investigations, these kidney neoplasms may originate from any part of the tubules, and not only from the epithelial cells of the proximal convoluted tubules, as was suggested by earlier findings that employed antibodies against the brush-border antigens. In addition, the demonstration of sialic-acid-substituted and, in particular, of free PNA-receptors, which represent the immunodominant group of the Thomsen-Friedenreich antigen, may supply useful information on an immunotherapy concept.