Bead-blood assays

The following example taken from our unpublished work [O. Siiman and A. Burshteyn] on CDS antibody-beads illustrates the strategies involved in obtaining optimum antibody-bead performance in bead-blood assays. The main factors... 

The test is a whole blood assay and uses fluorescence-labelled latex particles which are added to the heparinized whole blood sample. The PMN phagocytize the opsonised latex particles and the PMNL, having ingested fluorescent beads, are separated in a cell sorter and the size and fluorescence of the PMNL are determined. The mean fluorescence is equal to the number of latex particles ingested per cell. The phagocytosis index and percentage are calculated from the proportion of cells which underwent phagocytosis and that of the control. 

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. 

Fig. 10 Top, flow c flometric histogram of Flow-Cal 575 beads as in Fig. 9, but run at settings for CD38 assay. Middle, flow cytometric histogram of whole blood from an AIDS patient stained with CD3-F1TC/CD38-PE/CD8-PC5, x-axis represents CD-38-PE fluorescence intensity. Bottom, overlay of How-Cal 575 and CD38-PE histograms...

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