Detection of circulating tumour cells with the magnetic activated cell sorter.

A technique has been developed for the detection of tumour cells in blood with the magnetic activated cell sorter (MACS). Colonic carcinoma cell lines and disaggregated primary tumours were used to establish optimal conditions of separation. A murine monoclonal antibody specific for epithelial cells was added to the suspension of leucocytes and tumour cells, followed by magnetic labelled goat antimouse antibody. The labelled tumour cells were retrieved by passing this suspension through a MACS separation column in a strong magnetic field. Tumour cells were detected at a dilution of 10 cells per ml blood. Tumour cells were identified in mesenteric blood in three of 24 patients undergoing surgery for colorectal cancer. This study supports the use of the MACS to detect circulating tumour cells.