ENHANCED ASSESSMENT OF DNA PROLIFERATIVE INDEX BY DEPLETION OF TUMOR-INFILTRATING LEUKOCYTES PRIOR TO MONOCLONAL-ANTIBODY GATED ANALYSIS OFTUMOR-CELL DNA

Flow cytometry has become an important tool for the analysis of breast tumors, and assessment of S phase fraction and DNA ploidy are potenti al indicators of tumor aggression. Due to masking or dilution of infre quent tumor cell events, the presence of normal cell types, such as in flammatory cells and fibroblasts, can interfere with accurate DNA anal ysis of solid tumor samples. MDA-MB-17B-VII human breast carcinoma cel ls, WI-38 human lung fibroblast cells, and peripheral blood leukocytes were mixed, in varying proportions, in order to represent human breas t tumor samples. The cells were subsequently treated with CD45 conjuga ted magnetic microspheres to deplete tumor infiltrating leukocytes, th us enriching for tumor cells. The tumor cell mixtures were then staine d with a pancytokeratin specific monoclonal antibody or with a monoclo nal antibody that reacts with breast epithelial membrane antigen (EMA) . When used in combination with monoclonal antibody gating, utilizatio n of this bead-based technology resulted in enhanced precision of DNA analysis. (C) 1994 Wiley-Liss, Inc.