Recovery of white blood cells and platelets from leukoreduction system chambers of Trima Accel and COBE Spectra plateletpheresis devices.

Recently, Dietz and coworkers described a new source of viable peripheral blood mononuclear cells (PBMNCs) that they recovered from leukoreduction system chambers (LRSCs) of Trima Accel apheresis devices (Gambro BCT, Lakewood, CO) after routine donor plateletpheresis procedures. These white blood cells (WBCs), which are usually discarded, functioned excellently in conventional in vitro assays and therefore represent a potential and novel source for research-grade cellular products. In the following report, we describe our results comparing the yields of WBCs recovered from LRSCs in Trima Accel (software version 5.1, Gambro BCT) and COBE Spectra (software version 7.0, Gambro BCT) plateletpheresis devices. After a storage period of 2 hours at room temperature, we drained the contents of the LRSCs into 20-mL conical tubes. We counted WBCs, platelets (PLTs), and red blood cells with a blood cell counter (ADVIA 120, Bayer HealthCare Diagnostics Division, Tarrytown, NY) and quantified CD14+ monocytes by flow cytometry (FACSCalibur, BD, San Jose, CA), as previously described. WBC and PLT yields were significantly different for the plateletpheresis devices (Table 1). Lymphocyte yields were greater and more consistent than monocyte yields. The minimum and maximum monocyte yields differed by 10-fold. WBC yields from Trima Accel LRSCs were 30 times greater than those from COBE Spectra LRSCs. Dietz and coworkers recovered 1.88 ¥ 10 PBMNCs from Trima Accel LRSCs. We recovered a mean of 66.5 percent fewer PBMNCs (0.69 ¥ 10 PBMNCs) from Trima Accel LRSCs. These different results may reflect actual differences in recoveries between the two plateletpheresis devices or, possibly, different instrument settings during plateletpheresis collections. For our study, we used an anticoagulant ratio of 11:1, whereas the ratio was 13:1 in the study by Dietz and coworkers. Also, the draw management (6 vs. 3), return management (4 vs. 1), and maximal draw flow (medium vs. fast) were different in our study compared with that by Dietz and colleagues. Thus, direct comparison of the cell yields of both studies is limited. The wide range of CD14+ monocytes recovered in LRSCs could impair the consistency of the results of monocyte-derived dendritic cells (DCs). Typically, monocyte yields from the Trima Accel LRSCs consisted of only approximately 10 percent of the cell yield of a leukapheresis unit. With current culture techniques, the