A separation procedure for separating a selected desired or undesired population
from a biological sample utilizing relatively heavy, dense particles and gravity
sedimentation. The particles have one or more reactants bound thereto which are
specific to and will bind with the selected population. The particles preferably
are mixed with the sample by repeatedly causing the particles to settle through
a substantial portion of the sample to bind to the selected population. The particles
with the bound selected population then are allowed to preferentially settle in
the sample and the supernatant including an enriched population is separated from
the particles with the selected population bound thereto. The enriched populations
in the biological sample supernatant can be further enriched by multiple removal steps.
