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BACKGROUND:In preparation for a proposed consolidated testing service, Canadian Blood Services undertook the evaluation of a commercial test kit for the enumeration by flow cytometry of residual white blood cells (rWBCs) present in preserved samples recovered from leukoreduced (LR) blood and platelet products. STUDY DESIGN AND METHODS:The stability of preserved WBCs, the equivalency of WBCs used for spiking, test method precision, specificity, reliability, accuracy, and sensitivity were investigated. For comparative purposes, WBC counts were also determined by Nageotte as well as by flow cytometry. RESULTS: WBCs were stable up to 4 weeks at room temperature for all components by either method. Within methods, no differences were observed due to the source of WBC used for spiking purposes. By either method, test precision was acceptable (<20% coefficient of variation) and of similar reliability at a target value of 10 Ϯ 5 WBCs per mL. The flow cytometric method was shown to be more specific and accurate than the Nageotte method. Sensitivity by either method was 0.1 WBCs per mL. On average, Nageotte counts were lower than those observed by flow cytometry. CONCLUSIONS: These results demonstrate that WBCs in WBC stabilizing solution-treated samples from LR blood components were stabilized up to 4 weeks at room temperature and that rWBC determinations made with a WBC enumeration kit by flow cytometry have the required precision, specificity, reliability, and accuracy in the relevant test range. This validated WBC stabilization and flow cytometric counting method is considered acceptable as part of a quality control program for leukoreduced blood products.W ith the introduction of leukoreduction of blood and its components in many countries, the need arose for routine monitoring of the efficacy of leukoreduction of blood products. There are a number of manual and automated methods for assessing residual WBC (rWBC) counts in leukoreduced (LR) blood components. These include enumeration of white blood cells (WBCs) by flow cytometry, 1-6 microvolume fluorometry (IMAGN 2000, BD Biosciences, Mountain View, CA), [1][2][3]6 and Nageotte hemocytometer and microscopy. 1,3,4,6 Enumeration performed by flow cytometry has been performed predominantly on commercially available cytometers (FACScan or FACSCalibur, BD Biosciences; [1][2][3]5 or EPICS XL, Beckman Coulter, Fullerton, CA [2][3][4] ). Commercial kits or methods based on the same principles have been used for determination of rWBCs with commercially available flow cytometers (BD Biosciences; [1][2][3]5 Beckman Coulter; [2][3][4] or Cytoron,6 Ortho Diagnostics Systems, Raritan, NJ). Up to February 2006 at Canadian Blood Services (CBS), rWBC content of LR products was determined by Nageotte hemocytometer and microscopy or by flow cytometry. When large numbers of samples from singledonor platelets (PLTs) or red blood cell (RBC) units were involved, centers sent samples to an external facility (Pall Corp., Scientific and Laboratory Services, Port Washington, NY) for testing ...

The most commonly used stem cell source for both autologous and allogeneic transplantation is mobilized peripheral blood hematopoietic progenitor cells collected by apheresis. In the 1990s, an Italian group used the correlation between the preapheresis peripheral blood CD34+ cell count and the final number of CD34+ cells collected to devise a formula for "target value-tailored" (TVT) apheresis. Using local patient data, the Canadian Blood Services Stem Cell Laboratory created a similar model to determine the blood volume to process during apheresis collection. The objectives of this study were to determine the correlation between the number of CD34+ cells predicted by the TVT formula and the actual number of CD34+ cells collected and to determine whether the TVT formula remains predictive when applied to an external data set. All apheresis collections performed at the Ottawa Hospital between January 1, 2003 and October 2, 2013 were reviewed. The primary outcome was the correlation between the number of CD34+ cells predicted by the TVT formula and the actual number of CD34+ cells collected on day 1 of apheresis. For the external data set, all autologous collections performed at the London Health Sciences Centre between December 1, 2008 and December 1, 2013 were reviewed. The external data set was divided into test and validation sets to determine whether a model could be created to predict the final number of CD34+ cells collected on day 1 based on the preapheresis CD34+ count. A total of 1252 collections were included in the analysis. The Ottawa data set included 1012 collections, 836 of which were autologous and 176 of which were from donors. Of the autologous collections in Ottawa, 764 (92.5%) were first collections. In 759 (91%) collections, chemotherapy plus granulocyte colony-stimulating factor (G-CSF) was used as the mobilization regimen. In 747 collections (89%), only 1 collection day was required to achieve the desired number of CD34+ cells. The TVT estimate was highly predictive of the number of CD34+ cells × 10(6)/kg actually collected on apheresis day 1 (r = .90, P < .0001). The London data set included 240 autologous collections. All mobilizations were with G-CSF alone. For the test set, the precollection CD34+ count was highly predictive of the number of CD34+ cells × 10(6)/kg collected on day 1 of apheresis. Applying this model to the validation set, the correlation between the predicted and final and day 1 CD34+ cells × 10(6)/kg count was .9186 (P < .0001). Using a modified TVT approach, the preapheresis CD34+ count can be used to accurately predict the number of CD34+ cells × 10(6)/kg collected on day 1. This approach can be applied at other centers and for different diseases and mobilization regimens. This method can be used to individualize the blood volume processed and, thus, optimize resource utilization.

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