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