Differential composition and yield of leukocytes isolated from various blood component leukoreduction filters.

In Flanders, an estimated 300,000 leukoreduction filters are discarded as biological waste in the blood establishment each year. These filters are a possible source of fresh donor leukocytes for downstream purposes including research. We investigated leukocyte isolation from two types of filters either used for the preparation of platelet concentrates (PC-LRF) or erythrocyte concentrates (EC-LRF). Outcome parameters were leukocyte yield, differential count, turnaround time and effect of storage conditions. Leukocytes were harvested by reverse flow of a buffer solution. Control was the gold standard density gradient centrifugation of buffy coats. Total leukocyte number isolated from PC-LRF (1049 (± 40) x 106) was almost double that of control (632 (± 66) x 106) but the differential count was comparable. Total leukocyte number isolated from EC-LRF (78 (± 9) x 106) was significantly lower than control, but the sample was specifically enriched in granulocytes (81 ± 4%) compared to control (30 ± 1%). Isolation of leukocytes from either PC- or EC-LRF takes 20 min compared to 240 min for control density gradient centrifugation. Leukocyte viability is optimal when harvested on day 1 post donation (95 ± 0.9%) compared to day 3 (76.4 ± 2.4%). In conclusion, our study demonstrates that leukoreduction filters from specific blood component processing are easy to use and present a valuable source for viable leukocytes of all types.

Influence of the leukoreduction moment of blood components on the clinical outcomes of transfused patients in the emergency department.

OBJECTIVES: to investigate the influence of the leukoreduction moment (preor post-storage) of blood components on the clinical outcomes of patients transfused in the emergency department. METHODS: retrospective cohort study of patients aged 18 years or older who received preor post-storage leukoreduced red blood cell or platelet concentrate in the emergency department and remained in the institution for more than 24 hours. A generalized mixed-effects model was applied in the analyses. RESULTS: in a sample of 373 patients (63.27% male, mean age 54.83) and 643 transfusions (69.98% red blood cell), it was identified that the leukoreduction moment influenced the length of hospital stay (p<0.009), but was not dependent on the transfused blood component (p=0.124). The leukoreduction moment had no effect (p>0.050) on transfusion reactions, healthcare-associated infections, or mortality. CONCLUSIONS: patients who received pre-storage leukoreduced blood components in the emergency department had a shorter length of hospital stay.

Effect of post-storage filters vs. pre-storage filters for leukoreduction of blood components on clinical outcomes: a systematic review and meta-analysis.

BACKGROUND: Leukoreduction has been used to limit the risk of adverse events. The most commonly used methodology is filtration (pre- or post-storage). However, whether pre-storage filtration is better than post-storage filtration needs to be clearly defined, particularly for countries that still use post-storage filtration. This study aimed to synthesize the best available evidence on the effectiveness of pre-storage filters compared with post-storage filters for transfusion reactions, for the occurrence of infections, for the length of hospital stay, and for the death of patients undergoing leukoreduced transfusion. METHODS: We searched the MEDLINE (PubMed), CINAHL (EBSCO), PsycINFO (APA), Scopus (Elsevier), The Cochrane Library (J. Wiley), Web of Science Core Collection (Clarivate Analytics), Embase (Elsevier), and LILACS (VHL) databases and gray literature for eligible studies in August 2020 and updated the search in October 2023. The Joanna Briggs Institute critical assessment tools were applied to analyze the quality appraisal of the studies. GRADE was used to determine the certainty of the evidence. RESULTS: The meta-analysis showed that pre-storage filtration was a protective factor for the occurrence of febrile non-hemolytic transfusion reaction in red blood cells (RR 0.49, 95% CI 0.41-0.59) and platelet concentrate transfusions (RR 0.16, 95% CI 0.12-0.22). The same did not occur for post-surgical infection after platelet concentrate transfusions (RR 0.82, 95% CI 0.65-1.04). Only one study analyzed the length of hospital stay and showed no significant difference between patients who received leukoreduced transfusions according to the type of filter used. According to the GRADE criteria, the certainty of the evidence for febrile non-hemolytic transfusion reactions was low for red blood cells and very low for platelet concentrate due to the high risk of bias. Infection was a low risk due to imprecision. CONCLUSIONS: The results of this review showed that the certainty of recommending the best type of filter (pre- or post-storage) for the benefit of the outcomes analyzed is still fragile; therefore, more robust evidence is needed. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42020192202.

Leukocyte filtration and leukocyte modulation therapy during extracorporeal cardiopulmonary resuscitation in a porcine model of prolonged cardiac arrest.

Extracorporeal cardiopulmonary resuscitation (ECPR) is emerging as a feasible and effective rescue strategy for prolonged cardiac arrest (CA). However, prolonged total body ischemia and reperfusion can cause microvascular occlusion that prevents organ reperfusion and recovery of function. One hypothesized mechanism of microvascular "no-reflow" is leukocyte adhesion and formation of neutrophil extracellular traps. In this study we tested the hypothesis that a leukocyte filter (LF) or leukocyte modulation device (L-MOD) could reduce NETosis and improve recovery of heart and brain function in a swine model of prolonged cardiac arrest treated with ECPR. Thirty-six swine (45.5 ± 2.5 kg, evenly distributed sex) underwent 8 min of untreated ventricular fibrillation CA followed by 30 min of mechanical CPR with subsequent 8 h of ECPR. Two females were later excluded from analysis due to CPR complications. Swine were randomized to standard care (Control group), LF, or L-MOD at the onset of CPR. NET formation was quantified by serum dsDNA and citrullinated histone as well as immunofluorescence staining of the heart and brain for citrullinated histone in the microvasculature. Primary outcomes included recovery of cardiac function based on cardiac resuscitability score (CRS) and recovery of neurologic function based on the somatosensory evoked potential (SSEP) N20 cortical response. In this model of prolonged CA treated with ECPR we observed significant increases in serum biomarkers of NETosis and immunohistochemical evidence of microvascular NET formation in the heart and brain that were not reduced by LF or L-MOD therapy. Correspondingly, there were no significant differences in CRS and SSEP recovery between Control, LF, and L-MOD groups 8 h after ECPR onset (CRS = 3.1 ± 2.7, 3.7 ± 2.6, and 2.6 ± 2.6 respectively; p = 0.606; and SSEP = 27.9 ± 13.0%, 36.7 ± 10.5%, and 31.2 ± 9.8% respectively, p = 0.194). In this model of prolonged CA treated with ECPR, the use of LF or L-MOD therapy during ECPR did not reduce microvascular NETosis or improve recovery of myocardial or brain function. The causal relationship between microvascular NETosis, no-reflow, and recovery of organ function after prolonged cardiac arrest treated with ECPR requires further investigation.

A randomized control trial to compare mortality in recipients of leucoreduced and non-leucoreduced whole blood transfusion in patients with cancer in Uganda.

BACKGROUND: Mortality benefit of transfusion with leucoreduced whole blood has not been demonstrated in the sub-Saharan Africa (SSA). We compared mortality in patients with cancer transfused with leucoreduced and non-leucoreduced whole blood in a SSA setting. METHODS: An open-label randomized controlled trial was conducted at the Uganda Cancer Institute where participants were randomized in a 1:1 ratio into the leucoreduced and non-leucoreduced whole blood transfusion arms. Leucocyte filtration of whole blood was performed within 72 h of blood collection. Patients aged ≥ 15 years who were prescribed blood transfusion by the primary physicians were eligible for study enrolment. Mortality difference was analyzed using intention-to-treat survival analysis and cox proportional hazard model was used to analyze factors associated with mortality. RESULTS: There were 137 participants randomized to the leucoreduced and 140 to the non-leucoreduced arms. Baseline characteristics were similar between the two arms. The median number of blood transfusions received was 1 (IQR, 1-3) unit and 2 (IQR, 1-3) units in the leucoreduced and non-leucoreduced arms respectively, p = 0.07. The 30-day mortality rate in the leucoreduced arm was 4.6% (95% CI, 2.1-10) and was 6.2% (95% CI, 3.2-12.1) in the non-leucoreduced arm (p = 0.57), representing an absolute effect size of only 1.6%. Increasing age (HR = 0.92, 95% CI, 0.86-0.98, p = 0.02) and Eastern Co-operative Oncology Group (ECOG) performance score of 1 (HR = 0.03, 95% CI, 0.00-0.31, p < 0.01) were associated with reduced 30-day mortality. CONCLUSIONS: The study failed to demonstrate mortality difference between cancer patients transfused with leucoreduced and non-leucoreduced whole blood. Although this study does not support nor refute universal leucoreduction to reduce mortality in patients with cancer in SSA, it demonstrates the feasibility of doing transfusion RCTs in Uganda, where a multi-center trial with an appropriate sample size is needed. TRIAL REGISTRATION: Pan African Clinical Trial Registry, https://pactr.samrc.ac.za/ (PACTR202302787440132). Registered on 06/02/2023.

Effect of leukoreduction on the omics phenotypes of canine packed red blood cells during refrigerated storage.

BACKGROUND: Red blood cell (RBC) storage promotes biochemical and morphological alterations, collectively referred to as storage lesions (SLs). Studies in humans have identified leukoreduction (LR) as a critical processing step that mitigates SLs. To date no study has evaluated the impact of LR on metabolic SLs in canine blood units using omics technologies. OBJECTIVE: Compare the lipid and metabolic profiles of canine packed RBC (pRBC) units as a function of LR in fresh and stored refrigerated (up to 42 days) units. ANIMALS: Packed RBC units were obtained from 8 donor dogs enrolled at 2 different Italian veterinary blood banks. STUDY DESIGN AND METHODS: Observational study. A volume of 450 mL of whole blood was collected using Citrate-Phosphate-Dextrose-Saline-Adenine-Glucose-Mannitol (CPD-SAGM) transfusion bags with a LR filter to produce 2 pRBC units for each donor, without (nLR-pRBC) and with (LR-pRBC) LR. Units were stored in the blood bank at 4 ± 2°C. Sterile weekly samples were obtained from each unit for omics analyses. RESULTS: A significant effect of LR on fresh and stored RBC metabolic phenotypes was observed. The nLR-pRBC were characterized by higher concentrations of free short and medium-chain fatty acids, carboxylic acids (pyruvate, lactate), and amino acids (arginine, cystine). The LR-pRBC had higher concentrations of glycolytic metabolites, high energy phosphate compounds (adenosine triphosphate [ATP]), and antioxidant metabolites (pentose phosphate, total glutathione). CONCLUSION AND CLINICAL IMPORTANCE: Leukoreduction decreases the metabolic SLs of canine pRBC by preserving energy metabolism and preventing oxidative lesions.

Effect of leukoreduction on the metabolism of equine packed red blood cells during refrigerated storage.

BACKGROUND: Understanding of the biochemical and morphological lesions associated with storage of equine blood is limited. OBJECTIVE: To demonstrate the temporal sequences of lipid and metabolic profiles of equine fresh and stored (up to 42 days) and leukoreduced packed red blood cells (LR-pRBC) and non-leukoreduced packed RBC (nLR-pRBC). ANIMALS: Packed RBC units were obtained from 6 healthy blood donor horses enrolled in 2 blood banks. METHODS: Observational study. Whole blood was collected from each donor using transfusion bags with a LR filter. Leukoreduction pRBC and nLR-pRBC units were obtained and stored at 4°C for up 42 days. Sterile weekly sampling was performed from each unit for analyses. RESULTS: Red blood cells and supernatants progressively accumulated lactate products while high-energy phosphate compounds (adenosine triphosphate and 2,3-Diphosphoglycerate) declined. Hypoxanthine, xanthine, and free fatty acids accumulated in stored RBC and supernatants. These lesions were exacerbated in non-LR-pRBC. CONCLUSION AND CLINICAL IMPORTANCE: Leukoreduction has a beneficial effect on RBC energy and redox metabolism of equine pRBC and the onset and severity of the metabolic storage lesions RBC.

Trend towards reduction of transfusion reactions using prestorage leukocyte-reduced and pooled whole blood-derived platelets and cost savings compared with poststorage whole blood-derived random platelets as evidenced by real-time hemovigilance.

BACKGROUND: Due to chemotherapy-induced neutropenia or hematologic malignancies, immunocompromised cancer patients may have higher incidence of febrile nonhemolytic transfusion reactions compared with the general population and frequently require platelet transfusions. This quality improvement project compared the safety of transfusion using prestorage leukocyte-reduced and pooled whole blood-derived platelets (Acrodose/WBD) with conventionally produced poststorage WBD platelets (RDP) using an active hemovigilance system. METHODS: Every patient receiving a blood product at the hospital was virtually monitored in real time by trained nurses from a remote hemovigilance unit. These nurses monitor a digital dashboard, which populates a watch list of patients from the time blood product administration is initiated until 12 hours posttransfusion. Over the course of 6 months, 371 patients receiving 792 RDP transfusions and 423 patients receiving 780 Acrodose/WBD platelets transfusions were monitored for transfusion reactions. RESULTS: We identified 26 transfusion reactions in RDP but only 12 transfusion reactions in the Acrodose/WBD platelet group. CONCLUSION: Acrodose platelet transfusion was associated with fewer transfusion reactions, which resulted in significant cost savings.

Delayed Leukoreduction of whole blood with a platelet-sparing filter to increase low-titer group O whole blood production in the United States.

BACKGROUND: Demand for low-titer Group O whole blood (LTOWB) is increasing for trauma. The whole blood (WB) platelet-sparing (WB-SP) filter enables leukoreduction (LR) while retaining platelet quantity and function; however, in the United States WB must be filtered and placed in the cold within 8 h of collection. A longer processing window would facilitate improved logistics and supply of LR-WB to meet the growing medical need. This study evaluated the impact of increasing filtration timing from <8 h to <12 h on the quality of LR-WB. STUDY DESIGN AND METHODS: Thirty WB units were collected from healthy donors. Control units were filtered within 8 h and test units within 12 h of collection. WB was tested throughout 21 days of storage. Hemolysis, WBC content, component recovery, and 25 additional markers of WB quality were tested including hematologic and metabolic markers, RBC morphology, aggregometry, thromboelastography, and p-selectin. RESULTS: There were 0 failures for residual WBC content, hemolysis, or pH, and no differences in component recovery between arms. Few differences in metabolic parameters were observed, but the small effect size suggests these are not clinically significant. Trends throughout storage were similar and filtration timing did not impact hematological parameters, platelet activation and aggregation, or hemostatic capacity. CONCLUSION: Our studies showed that extending filtration timing from 8 to 12 h from the collection does not significantly impact the quality of LR-WB. Characterization of the platelets demonstrated that storage lesions were not exacerbated. Extending the time from collection to filtration will improve LTOWB inventory in the United States.

Sickle cell trait results in a high leukoreduction quality control failure rate for whole blood donations.

BACKGROUND: Prior studies have shown that sickle cell trait (SCT) is the most common reason attributed to leukoreduction (LR) filter failure due to physical blockage. However, current Food and Drug Administration (FDA) guidelines do not require blood collectors to take a specific action to mitigate inadequate LR that may occur among donors with SCT. We sought to determine the scope of inadequate LR among whole blood (WB) donations collected from individuals with SCT and processed under standard manufacturing conditions. STUDY DESIGN AND METHODS: Between 8/2021 and 2/2022, a total of 40 red blood cells units (RBCs) manufactured from WB donations collected from donors historically positive for SCT had residual leukocyte testing performed. All 40 of the units had appeared to successfully complete leukofiltration. RESULTS: Out of the 40 units tested, 22 failed routine residual leukocyte quality control testing (55% failure rate, 95% confidence interval 40%-70%). Nine out of the 22 failures resulted in more than 100 residual leukocytes per microliter of product. CONCLUSION: Even when leukofiltration appears to have been completed successfully, WB units collected from donors with SCT have a high (55% in aggregate) rate of inadequate leukoreduction. Correlating this result with previous studies showing that of up to 50% of WB units collected from donors with SCT fail to pass through the leukoreduction filter, we estimate that only 25% of WB donations collected from individuals with SCT will result in a leukoreduced RBC unit that meets all FDA requirements. Blood centers should encourage individuals with SCT to donate platelets or plasma, rather than WB.

Minimal impact of anticoagulant on in vitro whole blood quality throughout a 35-day cold-storage regardless of leukoreduction timing.

BACKGROUND: There is increasing interest in leukoreduced whole blood (WB) as a transfusion product for trauma patients. In some jurisdictions, few leukoreduced filters are approved or appropriate for WB leukoreduction and quality information is therefore limited. This study assessed the impact of filtration timing of WB collected in CPDA-1 versus CPD on in vitro quality. STUDY DESIGN AND METHODS: WB was collected in CPDA-1 or CPD and leukoreduction filtered either after 3-8 h (early) or 18-24 h (late) from stop bleed time. In vitro quality was assessed after filtration and throughout 5 weeks of storage at 4°C. Cell count and hemoglobin levels were determined by hematology analyzer, platelet activation and responsiveness to ADP by surface expression of P-selectin by flow cytometry, hemolysis by HemoCue, and metabolic parameters by blood gas analyzer. Hemostatic properties were assessed by rotational thromboelastometry. Plasma protein activities and clotting times were determined by automated coagulation. RESULTS: Although there were some data points which showed statistically significant differences associated with anticoagulant choices or the filtration timing, no general trend in inferiority/performance could be discerned. After 35 days' storage, only clotting time, alpha angle and factor II in the early filtration arm comparing anticoagulants and prothrombin time and factor II in the CPDA-1 study arm comparing filtration timing showed a significant difference. CONCLUSION: In vitro WB quality seems to be independent on the choice of anticoagulant and filtration timing supporting WB hold-times to up to 24 h, increasing operational flexibility for transfusion services.

Leukocyte reduction filters as an alternative source of peripheral blood leukocytes for research

ABSTRACT Introduction: Peripheral blood leukocytes are a suitable cell model for science research. However, blood samples from healthy volunteers are limited in volume and difficult to obtain due to the complexity of volunteer recruitment. Objective: Therefore, it is urgent to find an alternative source of peripheral blood leukocytes. Method: One of the possibilities is the use of leukocyte reduction filters (LRFs) in blood banks that is used for preparation of leukoreduced blood products. More than 90% of the leukocytes are trapped in the leukofilters allowing the desired blood product to pass through. Results: It has been reported that the biological function of leukocytes collected from the filters are no different from those isolated from buffy coats, leukapheresis products and whole blood (WB) cells. Moreover, LRFs are waste products that are discarded after leukoreduction. Conclusion: Thus, leukofilters represent an economic source of human cell populations that can be used for a variety of investigative purposes, with no cost. In the present study, we reviewed the different usage of LRFs in the research, clinical and commercial applications.

Guideline development for prevention of transfusion-associated graft-versus-host disease: reduction of indications for irradiated blood components after prestorage leukodepletion of blood components.

Transfusion-associated graft-versus-host disease (TA-GVHD) is a rare, commonly fatal complication of transfusion preventable by irradiation of blood units. The revision of the Dutch transfusion guideline addressed the question whether irradiation is still necessary if blood components are prestorage leukodepleted. We searched for published cases of TA-GVHD following transfusion of prestorage leukodepleted blood and through contacting haemovigilance systems. Six presumed cases were found, dating from 1998 to 2013. Four out of six patients had received one or more non-irradiated units despite recognised indications for irradiated blood components. In the countries providing information, over 50 million prestorage leukodepleted, non-irradiated, non-pathogen-reduced cellular components were transfused in a 10-year period. Potential benefits of lifting indications for irradiation were considered. These include reduced irradiation costs (€ 1.5 million annually in the Netherlands) and less donor exposure for neonates. Findings were presented in an invitational expert meeting. Recommendations linked to human leukocyte antigen similarity between donor and recipient or intra-uterine transfusion were left unchanged. Indications linked to long-lasting deep T-cell suppression were defined with durations of 6 or 12 months after end of treatment (e.g. autologous or allogeneic stem cell transplantation). Need for continued alertness to TA-GVHD and haemovigilance reporting of erroneous non-irradiated transfusions was emphasised.

Supplemental findings of the 2019 National Blood Collection and Utilization Survey.

INTRODUCTION: Supplemental data from the 2019 National Blood Collection and Utilization Survey (NBCUS) are presented and include findings on donor characteristics, autologous and directed donations and transfusions, platelets (PLTs), plasma and granulocyte transfusions, pediatric transfusions, transfusion-associated adverse events, cost of blood units, hospital policies and practices, and implementation of blood safety measures, including pathogen reduction technology (PRT). METHODS: National estimates were produced using weighting and imputation methods for a number of donors, donations, donor deferrals, autologous and directed donations and transfusions, PLT and plasma collections and transfusions, a number of crossmatch procedures, a number of units irradiated and leukoreduced, pediatric transfusions, and transfusion-associated adverse events. RESULTS: Between 2017 and 2019, there was a slight decrease in successful donations by 1.1%. Donations by persons aged 16-18 decreased by 10.1% while donations among donors >65 years increased by 10.5%. From 2017 to 2019, the median price paid for blood components by hospitals for leukoreduced red blood cell units, leukoreduced apheresis PLT units, and for fresh frozen plasma units continued to decrease. The rate of life-threatening transfusion-related adverse reactions continued to decrease. Most whole blood/red blood cell units (97%) and PLT units (97%) were leukoreduced. CONCLUSION: Blood donations decreased between 2017 and 2019. Donations from younger donors continued to decline while donations among older donors have steadily increased. Prices paid for blood products by hospitals decreased. Implementation of PRT among blood centers and hospitals is slowly expanding.

Effect of leukoreduction and temperature on risk of bacterial growth in CPDA-1 whole blood: A study of Escherichia coli.

BACKGROUND: Collection of non-leukoreduced citrate-phosphate-dextrose-adenine (CPDA-1) whole blood is performed in walking blood banks. Blood collected under field conditions may have increased risk of bacterial contamination. This study was conducted to examine the effects of WBC reduction and storage temperature on growth of Escherichia coli (ATCC® 25922™) in CPDA-1 whole blood. METHODS: CPDA-1 whole blood of 450 ml from 10 group O donors was inoculated with E. coli. Two hours after inoculation, the test bags were leukoreduced with a platelet-sparing filter. The control bags remained unfiltered. Each whole blood bag was then split into three smaller bags for further storage at 2-6°C, 20-24°C, or 33-37°C. Bacterial growth was quantified immediately, 2 and 3 h after inoculation, on days 1, 3, 7, and 14 for all storage temperatures, and on days 21 and 35 for storage at 2-6°C. RESULTS: Whole blood was inoculated with a median of 19.5 (range 12.0-32.0) colony-forming units per ml (CFU/ml) E. coli. After leukoreduction, a median of 3.3 CFU/ml (range 0.0-33.3) E. coli remained. In the control arm, the WBCs phagocytized E. coli within 24 h at 20-24°C and 33-37°C in 9 of 10 bags. During storage at 2-6°C, a slow self-sterilization occurred over time with and without leukoreduction. CONCLUSIONS: Storage at 20-24°C and 33-37°C for up to 24 h before leukoreduction reduces the risk of E. coli-contamination in CPDA-1 whole blood. Subsequent storage at 2-6°C will further reduce the growth of E. coli.

Cold-stored leukoreduced whole blood: Extending the time between donation and filtration has minimal impact on in vitro quality.

BACKGROUND: Leukoreduced whole blood (LR-WB) has received renewed attention as alternative to component-based transfusion in trauma. According to the manufacturer's instructions, leukoreduction should be carried out within 8 h after collection. This study assessed impact of (1) WB collection bag, (2) LR filtration, and (3) timing of filtration on in vitro quality. STUDY DESIGN AND METHODS: WB collected into different vendor bags was held at room temperature for <8 h or >16 h but <24 h prior to LR. In vitro quality was assessed before and after filtration, and throughout 3 weeks of storage at 4°C. Cell count and hemoglobin levels were determined by hematology analyzer, platelet activation, and responsiveness to ADP by surface expression of P-selectin by flow cytometry, hemolysis by HemoCue, and metabolic parameters by blood gas analyzer. Hemostatic properties were assessed by rotational thromboelastometry. Plasma protein activities and clotting times were determined by automated coagulation analyzer or quantitative immunoblotting. RESULTS: Bag type had no impact on WB in vitro quality. LR by filtration had some impact, but is aligned with data in the literature. The time between donation and filtration resulted in some statistically significant differences in metabolic activity, platelet yield, platelet activation, and factor protein activity initially; however, these differences in in vitro quality attributes decreased throughout 21-day cold storage. CONCLUSION: WB hold time showed only a minor impact on WB in vitro quality, so it may be possible for blood processing facilities to explore extended hold times prior to filtration in order to provide greater operational flexibility.

Platelet aggregation in whole blood is not impaired by a platelet-sparing leukoreduction filter and instead depends upon the presence of leukocytes.

BACKGROUND: Recent studies characterizing in vitro hemostatic properties of whole blood (WB) leukoreduced (LR) with a platelet-sparing filter have described subtle, if any, changes to viscoelastic clotting; however, reductions in platelet (PLT) content and impedance aggregometry (IA) responses have been noted. The effects of filtration of WB (i.e., filter-contact effects, reduction in platelet and leukocyte count) have not been rigorously investigated as to their individual impacts on platelet IA responses. STUDY DESIGN AND METHODS: WB units from healthy donors were collected and characterized to assess the effects of platelet-sparing leukoreduction (LR) upon the in vitro hemostatic measures of platelet IA and thromboelastometry. Further characterization of platelet IA responses was carried out in WB samples to delineate the effects of platelet count and leukocyte presence/absence upon the response. RESULTS: WB filtration reduced the platelet count and IA responses but had no impact on viscoelastic clotting measures in fresh WB. Experiments revealed that IA responses have a linear correlation with platelet count in both apheresis platelets and WB and that passage of platelets through the WB-LR filter has no impact upon the strength of this response. Further experiments in LR WB showed that addition of autologous leukocytes back to the platelets fully restored the platelet aggregation response to pre-filtration levels. CONCLUSION: WB filtration results in platelet count reduction and leukocyte removal; however, platelet IA is not degraded by passage through the filter. Apparent declines in platelet IA responses can be fully attributed to the reduction in platelet count and the removal of leukocytes.

Enrichment of leukocytes in peripheral blood using 3D printed tubes.

Leukocytes have an essential role in patient clinical trajectories and progression. Traditional methods of leukocyte enrichment have many significant limitations for current applications. It is demonstrated a novel 3D printing leukocyte sorting accumulator that combines with centrifugation to ensure label-free initial leukocyte enrichment based on cell density and size. The internal structure of leukocyte sorting accumulator (revealed here in a new design, leukocyte sorting accumulator-3, upgraded from earlier models), optimizes localization of the buffy coat fraction and the length of the period allocated for a second centrifugation step to deliver a higher recovery of buffy coats than earlier models. Established methodological parameters were evaluated for reliability by calculating leukocyte recovery rates and erythrocyte depletion rates by both pushing and pulling methods of cell displacement. Results indicate that leukocyte sorting accumulator-3 achieves a mean leukocytes recovery fraction of 96.2 ± 2.38% by the pushing method of layer displacement. By the pulling method, the leukocyte sorting accumulator-3 yield a mean leukocytes recovery fraction of 94.4 ± 0.8%. New procedures for preliminary enrichment of leukocytes from peripheral blood that avoid cellular damage, as well as avert metabolic and phase cycle intervention, are required as the first step in many modern clinical and basic research assays.