TRISOMY-7 IN NONNEOPLASTIC EPITHELIAL KIDNEY-CELLS

Trisomy 7 has been found as the sole clonal chromosome aberration in a number of tumor types, including renal cell carcinomas (RCC), and als o in non-neoplastic kidney tissue. It has recently been proposed that the cells harboring trisomy 7 in RCC and in the surrounding tissue may be tumor infiltrating T-helper lymphocytes. We performed cytogenetic analysis of metaphase cells and FISH of interphase nuclei in unculture d and cultured non-neoplastic kidney tissues from 13 patients with ren al or urothelial carcinomas, and 4 patients with inflammatory kidney d iseases. FISH analysis showed that the frequency of +7 varied between 1.0-8.9% (mean 3.3%) in uncultured cells and between 0.4-8.6% (mean 4. 4%) after one week of cell culture. The frequency of + 7 after one wee k of culture was 1.0-19.0% (mean 6.1%) as determined by cytogenetic an alysis. Immunoenzymatic staining of both uncultured and cultured cells with the alkaline phosphatase reaction and monoclonal antibodies for CD3 showed that the frequency of T-cells in uncultured cells and in pr imary cultures varied between 2.9-10%. The number of T-cells decreased with time and number of in vitro passages to less than 1% after 7-8 w eeks, but the frequency of +7 remained fairly constant. Combination of FISH with immunostaining using CD3 for T-lymphocytes and cytokeratins for epithelial cells showed that the cells with +7 were mainly epithe lial cells whereas only 0-5% were T-lymphocytes. The results have obvi ous implications for the interpretation of the significance of trisomy 7 in neoplasia.