Coulter ® STKS2B hematology analyzer

Various titers, 1-50 pL, of lot no. 1, 4.2% w/v solids, CDS antibody beads were mixed in duplicate for 8 min with 4(X)pL of whole blood from three donors to establish the dependence of %CD3 (Table 3) in the Coulter STKS2B hematology analyzer assay on bead titer. 

Thus, lot no. 1 beads were then used in a statistical measurement run with two donors and eleven measurements per donor at bead titers of lOpL and 25 pL of 4% w/v solid beads per 400 pL of whole blood, mixed together for 6 min. For one donor, the mean %CD3+ lymphocytes was 74.28(2.45) at a 10 pL titer and 76.98(1.40) at the 25 pL titer versus 77.1 for the flow comparator. The second donor gave 69.60(1.95) at the lOpL titer and 74.50(1.54) at the 25pL titer versus 76.6 for the flow comparator. The mean percentage CDS should have an interassay precision within three standard deviations, and preferably, within two standard deviations. The accuracy of the Coulter STKS2B hematology analyzer measurements as determined by a comparison with data from flow cytometry was within 5% of the comparator for the standard titer of 25 pL of 4% w/v solid beads per 400 pL of whole blood. 

For an average 75% CD3+ lymphocytes out of 4.8-13.6 x 10 lymphocytes per 400pL of whole blood, we have 3.6-10.2 x 10 CD3+ cells. For 2.4pm diameter beads at 4.2% w/v solids, we have 5.50 x 10 beads/mL, so that our standard titer of 25 pL of 4.2% w/v solid beads per 400 pL of whole blood on the Coulter STKS2B hematology analyzer will contain 1.375x 10 beads. The range of bead-to-cell ratio is then 135-382. 

---