A method of harvesting a predetermined component contained in a fluid,
comprising adding an aliquot of said fluid via the inlet tube of a
rotating centrifuge container comprising at least one inlet tube and at
least one outlet tube, wherein the fluid separates radially into
fractions. The distal end of the outlet tube is in flow communication with
the desired component. The desired component is removed from the rotating
container via the outlet tube, and withdrawal is terminated when an
undesired fraction is detected to be near the distal end of the outlet
tube. In one embodiment the container is a doughnut shaped flexible bag.
In an alternative method the centrifuge container is a rigid container
having an interior collection chamber for receiving said whole blood and
having a generally off-centered figure eight-shaped side cross-sectional
configuration.