MAGNETIC FLOW SORTING USING A MODEL SYSTEM OF HUMAN-LYMPHOCYTES AND ACOLLOIDAL MAGNETIC LABEL

Cells of identical physical properties that differ in the expression o f surface proteins can be sorted conveniently using immunospecific sta ins conjugated to fluorescent, or magnetic, labels. Immunomagnetic cel l sorting using commercial batch sorters offers advantages of high sor ting capacity, high viability of sorted fractions, and high depletion rates; its disadvantages are low enrichment rate and batch processing. The authors developed and tested a continuous, flow-through magnetic cell sorter for small volume, experimental cell enrichment. Freshly is olated human peripheral lymphocytes were labeled using an immunofluoro magnetic sandwich consisting of mouse anti human CD8 monoclonal antibo dy-fluorescein conjugate and rat anti mouse polyclonal antibody-colloi dal iron-dextran conjugate. A total of 2-3 min lymphocytes were sorted per hour using a saturation magnetic field of 1.334 T and a five chan nel sorter. The fluorescent cells were distributed among the channels in relation to their fluorescence intensity and magnetic susceptibilit y. The purity (68-85%) and enrichment rates (16-34X) were comparable t o those of commercial batch magnetic separators; sorting capacity and recovery of the enriched fractions (up to 32%) were limited by the sma ll scale of the sorter. Future direction is focused on increasing the resolution, recovery, and sorting capacity of the enriched fractions, and testing the sorter on other cell systems.