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.