CONTINUOUS, FLOW-THROUGH IMMUNOMAGNETIC CELL SORTING IN A QUADRUPOLE FIELD

A flow-through quadrupole magnetic cell separator has been designed, b uilt, and evaluated by using a cell model system of human peripheral T lymphocytes (CD4(+), CD8(+), and CD45(+) cells). The immunomagnetic l abeling was accomplished by using a sandwich of mouse anti-human monoc lonal antibody conjugated to fluorescein isothiocyanate and rat anti-m ouse polyclonal antibody conjugated to a colloidal magnetic nanopartic le, The feed and sorted fractions were analyzed by FACScan now cytomet ry, The magnetically labeled cells were separated from nonlabeled. one s in a flow-through cylindrical column within a quadrupole field, whic h exerted a radial, outward force on the magnetic cells. The flow rate of the cell samples was 0.1-0.75 ml/min, and the flow rate of sheath fluid was 1.5-33.3 times that of the sample flow rate, The maximum she ar stress exerted on the cell was less than 1 dyne/cm(2), which was we ll below the level that would threaten cell integrity and membrane dis ruption, The maximum magnetic field was 0.765 T at the channel wall, a nd the gradient was 0.174 T/mm, The highest purity of selected cells w as 99.6% (CD8 cells, initial purity of 26%), and the highest recovery of selected cells was 79% (CD4 cells, Initial purity of 20%), The maxi mum throughput of the quadrupole magnetic cell separator was 7,040 cel ls/s (CD45 cells, initial purity of 5%). Theoretical calculations show ed that the throughput can be increased to 10(6) cells/s by a scale-up of the current prototype, (C) 1998 Wiley-Liss, Inc.