Lanthanides as soluble paramagnetic agents for magnetic filtration of cells

Abstract Separation of cells by magnetic techniques is an attractive concept, but present methods have inherent disadvantages. A promising new technique, which depends on the use of lanthanides as soluble paramagnetic agents, has been investigated. Blood cells, permitted to bind chelated lanthanides from their suspending medium, acquire sufficient cellular magnetic moment that they can be filtered magnetically with high efficiency. Spectroscopy of cellular volumes and spectrophotometry for extracellular hemoglobin show that the experimental diluents have a negligible effect on cellular integrity, and visual microscopy demonstrates essentially normal cellular morphology in wet mounts made from the suspensions. Cellular aggregation by the lanthanides is prevented by the chelation process, despite lanthanide concentrations of 50 mM in some of the experimental diluents. The feasibility experiments are discussed, and filtration dependence on chelate concentration is illustrated.