DartLab offers cell subset enrichment services using either Fluorescence Activated Cell Sorting or magnetic beads.
The principles of separation for magnetic bead enrichment using StemCell products may be found here.
A very helpful tool to establish expected numbers of cell counts from healthy human blood is the Frequencies of Cell Types chart published by StemCell Technologies.
Overview of human peripheral blood leukocytes (from Wikipedia)
Reference ranges for leukocyte subsets from Dartmouth Hitchcock Medical Center (DHMC) Pathology Department: