Abstract
Background : A PBSC graft containing 4-5 2 10 6 CD34 + cells/kg is considered optimal in terms of durable engraftment. Tracking CD34 kinetics via point-of-care testing during PBSC mobilization could determine which (and when) patients will yield an optimal product. We evaluated whether microvolume fluorimetry (MVF) would be useful in optimizing PBSC mobilization/harvest and if it will shorten our standard 6 h collection. Methods : Absolute CD34 values were obtained using the IMAGN 2000 and STELLer CD34 assay (50 w L sample volume). Peripheral blood (PB) CD34 values from 30 patients undergoing PBSC mobilization were used to generate a PB CD34-based algorithm that would predict collection day/duration of apheresis. The algorithm was then used prospectively to collect PBSC products on 50 hematologic malignancy (HM) patients. Results : Using the algorithm, patients were assigned to either a 6 (11-20 CD34/ w L), 4 (21-49 CD34/ w L) or 2 (S 50 CD34/ w L) h collection. Patients with a CD34 value h 10/ w L were re-tested. All patients (n = 43) predicted to mobilize reached the optimal CD34 (4-5 2 10 6 /kg) value with 1.0 apheresis procedure; seven patients had h 10/ w L (nonmobilizers). The majority (75%) had apheresis charges decreased by 33-66%; 47% only required a 2 h procedure and 28% required 4 h. All patients demonstrated rapid trilineage engraftment. Discussion : Absolute PB CD34 measurement using MVF offers a rapid and reliable approach to obtaining optimal PBSC products with minimal technical expertise. Although not a replacement for conventional flow cytometry, it meets the requirements for a point-of-care procedure.