Magnetophoretic mobilities correlate to antibody binding capacities

Methods: A methodology and a mathematical theory have been developed, which allow quantitation of the expression levels of cellular surface antigens u sing immunomagnetic labels and cell tracking velocimetry (CTV) technology. Results: Quantum Simply Cellular (QSC) microbeads were immunomagnetically l abeled with anti-CD2 fluorescein isothiocyanate (FITC) antibodies and anti- FITC MACS paramagnetic nanoparticles. Magnetophoretic mobility has been def ined as the magnetically induced velocity of the labeled cell or microbead divided by the magnetophoretic driving force, proportional to the magnetic energy density gradient. Discussion: Using computer imaging and processing technology, the mobility measurements were accomplished by microscopically recording and calculating the velocity of immunomagnetically labeled QSC microbeads in a nearly cons tant magnetic energy gradient. A calibration curve correlating the measured magnetophoretic mobility of the immunomagnetically labeled microbeads to t heir antibody binding capacities (ABC) has been obtained. Conclusion: The results, in agreement with theory, indicate a Linear relati onship between magnetophoretic mobility and ABC for microbeads with less th an 30,000 ABC. The mathematical relationships and QSC standardization curve obtained allow determination of the number of surface antigens on similarl y immunomagnetically labeled cells. (C) 2000 Wiley-Liss, Inc.