Detection and enrichment of disseminated renal carcinoma cells from peripheral blood by immunomagnetic cell separation

We have established an immunomagnetic separation procedure for the detectio n of circulating tumor cells in the peripheral blood based on the magnetic cell sorting (MACS) technique. In previous in vitro experiments, renal-cell carcinoma (RCC) cells were mixed with peripheral blood, In dilutions of 1: 200 to 1:10(7) tumor cells per mononuclear blood cells, an average recovery rate of 84% of tumor cells was determined. In our study, 104 peripheral bl ood samples from 59 renal carcinoma patients were analyzed. MACS resulted i n significant depletion of leukocytes, permitting a search for tumor cells on just 1 slide. Analyzing 8 ml of peripheral blood per patient, 19/59 RCC patients carried disseminated tumor cells (32%) in the range of 1 to 38 cel ls (median 8). Interestingly, for the cytokeratin-positive (CK) patient gro up, we found a correlation between tumor cell number and grading (G2 vs. G3 ) and an increased number of CK+ patients with advanced tumor stage. MACS a ppears to be an efficient technique to detect disseminated tumor cells in p eripheral blood. (C) 2001 Wiley-Liss, Inc.