TRISOMY-7 IN NONNEOPLASTIC TUBULAR EPITHELIAL-CELLS OF THE KIDNEY

The cellular origin of trisomy 7 in non-neoplastic kidney tissue speci mens from 10 patients, seven with malignant tumors and three with non- neoplastic kidney diseases, was studied by the MAC (morphology anti bo dy chromosomes) technique, which allows analysis of cellular morpholog y/histology, immunophenotype, and chromosomal aneuploidy by convention al cytogenetics, and/or fluorescent in situ hybridization in both inte rphase and mitotic cells. In primary cultures, trisomy 7 was detected primarily in cytokeratin-positive cells. Among freshly isolated renal cells, the trisomy was mainly observed in proximal tubular cells posit ive to brush-border antigen, and, to a lesser extent, in distal tubula r cells positive to Tamm-Horsfall glycoprotein. The frequency of triso my 7 in lymphocytes expressing CD3 or CD22 antigens isolated from non- neoplastic and tumor tissues was substantially lower than in the epith elial cells and was not increased compared with that in control lympho cytes from peripheral blood. The results thus demonstrate that the non -neoplastic kidney cells with trisomy 7 are mainly normal epithelial c ells, preferentially those of the proximal tubule.