Immunomagnetic colloids for the enrichment of tumor cells from peripheral blood and bone marrow: a model system.

The characterization of tumor cells in bone marrow harvested for autologous bone marrow rescue remains a problem due to the limited sensitivities of the techniques available for their analysis. This complicates the use of purging techniques as their usefulness is debated, specifically because it is not known if they can remove all residual tumor cells from either peripheral blood stem cell harvests or bone marrow. Apart from developing more sensitive techniques for tumor detection, one way of increasing our efficiency at identifying rare malignant cells in normal hematopoietic cells is to develop approaches to enrich the population of interest prior to analysis. Here, we describe a laboratory-based system for tumour enrichment employing panels of monoclonal antibodies (MAbs) and an immunomagnetic colloid. In model systems, tumor cells could be enriched approximately 100-fold with high yield and purity. The adaptations of this technology to permit further cell enrichment and the choice of either an immunological technique or a molecular approach to tumor identification are discussed in detail.