ABSTRACT
Detection and quantitation of epithelial tumor cells that have metastasized to the peripheral blood or marrow are potentially important for staging disease and evaluating cell preparations for autologous transplantation after myeloablative chemotherapy. The cytokeratins are well accepted as the most specific marker for epithelial cells, with essentially no background expression on blood leukocytes or erythrocytes (25). This is essential since the target cells are present at extremely low levels (< 10-6) even in patients with late-stage disease. Permeabilization of the cells allows anticytokeratin magnetic beads to bind the Ag residing just below the plasma membrane. Griwatz et al. (26) have used preformed mouse anticytokeratin/rat-antimouse immunoglobulin mag netic beads and Siewert and coworkers (27,28) and Qian et al. (29) have used direct-conjugate anticytokeratin magnetic beads.
