Leukocyte Reduction Filters Research Articles

Leukocyte-Poor Platelet-Rich Plasma for the Management of Knee Osteoarthritis: A Retrospective Study With 12 Months of Follow-Up.

Introduction The knee, the most frequently affected joint in osteoarthritis (OA), impacts the life quality of millions of individuals globally, resulting in a considerable healthcare burden. Conservative treatments are preferred, turning to surgical intervention when necessary. Nonetheless, these conventional modalities have drawbacks. Recently, the use of regenerative medicine therapies, including autologous peripheral blood-derived orthobiologics (APBOs), such as leukocyte-poor platelet-rich plasma (LP-PRP), has evolved and demonstrated the ability to manage knee OA. The primary objective of this investigation was to evaluate the efficacy of LP-PRP via widely used patient-reported outcome measures (PROMs) in grade I or II (on the Kellgren-Lawrence scale) knee OA patients. The secondary objective was to characterize the formulated LP-PRP and determine the efficiency of the leukodepletion filter used for leukocyte removal and platelet recovery. Methods This investigation was a retrospective analysis of data collected from patients treated at a single center over a period of 15 months.Data from 40 patients included in this study were intra-articularly injected with 3mL of formulated LP-PRPunder ultrasound guidance. PROMs questionnaires, including Kujala and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores, were used and responses were documented at baseline and up to 12 months follow-up. The characterization of the formulated LP-PRP and the efficiency of the leukodepletion filter in removing leukocytes and recovering platelets were assessed via complete blood count (CBC) analysis. Results The intra-articular administration of LP-PRP resulted in statistically significant improvements in Kujala and WOMAC scores in patients with Grade I or II OA of the knee at all follow-up time points (four to 12 months) compared to the respective baseline scores. The subgroup analysis showed significant improvements in Kujala and WOMAC scores inboth male and female grade I or II knee OA patients with or without comorbidities, including diabetes and/or hypertension. The characterization of formulated PRP showedplatelet concentration to be at least 6x compared to the baseline whole blood levels, the absolute platelet count to be at least 5 billion, and total leukocytes, lymphocytes, neutrophils, and RBCs were depleted by over 88%, 82%, 98%, and 98%, respectively. In addition, the utilization of the PuriBlood leukocyte reduction filter (Puriblood Medical Co. Ltd., Baoshan Township, Taiwan) led to the depletion of approximately 93% of leukocytes and the recovery of about 83% of platelets. Conclusions Administration of LP-PRP resulted in significant improvements in pain and function of patients suffering from grade I or II OA of the knee. In addition, the leukodepletion filter used to formulate LP-PRP, successfully resulted in the depletion of leukocytes while recovering the platelets. More sufficiently powered, multi-center, prospective, non-randomized, and randomized controlled trials with long-term follow-up are needed to further establish the effectiveness of this formulation in knee OA patients.

Blood salvage and autotransfusion during orthotopic liver transplantation for hepatocellular carcinoma: A systematic review and meta-analysis.

Hepatocellular carcinoma (HCC) is a significant cause of oncologic mortality worldwide. Liver transplantation represents a curative option for patients with significant liver dysfunction and absence of metastases. However, this therapeutic option is associated with significant blood loss and frequently requires various transfusions and intraoperative blood salvage for autotransfusion (IBS-AT) with or without a leukocyte reduction filter. This study aimed to analyze available evidence on long-term oncologic outcomes of patients undergoing liver transplantation for HCC with and without IBS-AT. Per PRISMA guidelines, a systematic review of keywords "Blood Salvage," "Auto-transfusion," "Hepatocellular carcinoma," and "Liver-transplant" was conducted in PubMed, EMBASE, and SCOPUS. Studies comparing operative and postoperative outcomes were screened and analyzed for review. Twelve studies totaling 1704 participants were included for analysis. Length of stay, recurrence rates, and overall survival were not different between IBS-AT group and non IBS-AT group. IBS-AT use is not associated with increased risk of recurrence in liver transplant for HCC even without leukocyte filtration. Both operative and postoperative outcomes are similar between groups. Comparison of analyzed studies suggest that IBS-AT is safe for use during liver transplant for HCC.

Cytomegalovirus-Seronegative Plus Leukoreduced Blood Products Are Still Superior to Only Leukoreduced Products in Preventing Transfusion-Transmitted Cytomegalovirus Infection

Introduction Cytomegalovirus (CMV) is one of the most important pathogens causing complications after hematopoietic stem cell transplantation (HSCT). Transfusion-transmitted CMV infection (TT-CMV) in CMV-seronegative patients is a major issue. Leukoreduced (LR) blood products were unavailable before 2004. However, they have gradually become widespread, and all blood products in Japan have been LR since 2007. This study aimed to assess the incidence of TT-CMV in CMV-seronegative HSCT recipients undergoing autologous HSCT (auto-HSCT) or allogeneic HSCT (allo-HSCT) from CMV-seronegative stem cell donors, who received transfusions with “CMV-seronegative products” from CMV-seronegative donors or “random donor products” from donors not tested for anti-CMV antibodies during the periods of availability and unavailability of LR products. Methods We retrospectively evaluated 3590 CMV-seronegative recipients registered in the TRUMP database of the Japanese Society for Transplantation and Cellular Therapy from 1999 to 2018. The recipients undergoing HSCT were categorized into three periods: Period A (when LR products were unavailable), 1999-2003 (n = 136); Period B (when there were both non-LR and LR products), 2004-2006 (n = 200); and Period C (when only LR products were available), 2007-2018 (n = 3254). TT-CMV was defined by the presence of CMV antigenemia and/or CMV diseases. This study was approved by the Ethics Committee of Kobe University Hospital and was conducted in accordance with the principles of the Declaration of Helsinki. Results The median age of the patients at HSCT was 40 years (range, 0-79 years). Among auto-HSCT patients (n = 1628) transfused with “CMV-negative products”(CN group) and “random donor products” (RD group), the incidences of TT-CMV in the CN and RD groups were 0% (0/4) and 3.1% (1/32) during Period A (P = 1.0), 22.2% (2/9) and 10.6% (7/66) during Period B (P = 0.29), and 3.8% (4/105) and 5.0% (71/1412) during Period C (P = 0.81), respectively. Among the allo-HSCT patients (n = 1962), the incidences of TT-CMV in the CN and RD groups were 10.0% (3/30) and 27.1% (19/70) during Period A (P = 0.07), 17.9% (5/28) and 29.9% (29/97) during Period B (P = 0.24), and 11.6% (41/355) and 28.0% (387/1382) during Period C (P < 0.001), respectively. During Period C, 99 patients in the CN group always underwent transfusion with leukocyte reduction filters, of which 11 (11.1%) were diagnosed with TT-CMV. In contrast, 202 patients in the CN group always underwent transfusion without the filters, of which 26 (12.9%) were diagnosed with TT-CMV (P = 0.78). In the RD group, 494 patients always underwent transfusion with leukocyte reduction filters, of which 124 (25.1%) were diagnosed with TT-CMV. On the other hand, 807 patients in the RD group always underwent transfusion without the filters, of which 245 (30.4%) were diagnosed with TT-CMV (P = 0.10). Multivariate analysis revealed that random donor products (hazard ratio [HR]: 3.11, 95% confidence interval [CI]: 2.13-4.52; P < 0.001) and age ≥16 years (HR: 2.90, 95% CI: 2.06-4.09; P < 0.001) were associated with an increased risk of TT-CMV in allo-HSCT. No significant difference was observed in the incidence of CMV diseases between the CN group (3.7%; 13/355) and the RD group (3.8%; 52/1382) (P = 1.00). The major CMV diseases included CMV colitis (n = 5) and pneumonia (n = 2) in the CN group, and CMV colitis (n = 30), pneumonia (n = 9), and retinitis (n = 4) in the RD group. Interestingly, among the patients with TT-CMV during Period C, 27/41 patients (65.9%) in the CN group and 333/387 patients (86.1%) in the RD group received early intervention with anti-CMV agents (P = 0.002). The limitation included that complement-fixation test for anti-CMV antibody was used in Japan Marrow Donor Program in this cohort. Conclusion This is the largest study demonstrating that CMV-seronegative plus LR products are still superior to only LR products from random donors in terms of TT-CMV prevention among allo-HSCT CMV-seronegative recipients. However, no significant difference was observed in the incidence of CMV diseases, possibly because of early intervention with anti-CMV agents.

Leukocyte Reduction Filters Are Reliable and Economic Source for Natural Killer Cell Preparation.

An issue that hinders researchers' access to Natural Killer (NK) cells is their low proportion in peripheral blood leukocytes. This issue is currently addressed by methods involving a series of differentiation and expansions that are time-consuming and expensive. We have investigated whether the used leukocyte reduction filters, a by-product in the blood transfusion practice that currently is considered waste, can be utilized as a source of the NK cells. Following the blood donation of 46 donors based on the Iranian Blood Transfusion Organization's protocols, a sample of peripheral blood of each donor and the leukocyte reduction filter used in their donation procedure have been obtained. The entrapped cells were flushed back from the leukocyte reduction filters. Both groups of samples were analyzed using an automatic hematological analyzer. NK cell isolation was done by the MACS negative selection method. The samples have been comparatively analyzed utilizing flow cytometry data of NK cells' subpopulation compositions, viability, degranulation patterns, and cytotoxic capacity against the K562 cell line. Every major leukocyte population was abundant in the samples extracted from the used leukocyte reduction filters. The NK cells extracted from leukocyte reduction filters did not show any statistically meaningful differences (P<0.5) from peripheral blood samples in terms of subpopulation composition, viability, degranulation potency, and cytotoxic capacity. Used leukocyte reduction filters can be considered an economic, easy to obtain, and robust source of abundant research-grade NK cells.

Adverse Events Associated with the Use of Leukocyte Reduction Filters and Blood Transfusion Sets: Experience of a Single Institute in Korea and Status of Adverse Event Reporting in Korea and the United States

Adverse Events Associated with the Use of Leukocyte Reduction Filters and Blood Transfusion Sets: Experience of a Single Institute in Korea and Status of Adverse Event Reporting in Korea and the United States

A Quality Approach to Reducing the Occurrence of Occluded Leukocyte Reduction Filters During Platelet Transfusion.

A Quality Approach to Reducing the Occurrence of Occluded Leukocyte Reduction Filters During Platelet Transfusion.

Preparation of clinical-grade WBCs using leukocyte reduction filters

ObjectiveOur goal was to develop a simpler and less expensive method of obtaining human clinical-grade WBCs using an alternative method to continuous leukapheresis. Our purpose for the WBCs is to arm them with rabbit anticancer antibodies for a phase I clinical trial. MethodsUsing leukocyte reduction filters (LRFs) discarded from the blood bank, we evaluated multiple variables to maximize recovery of WBCs with the lowest contamination of RBCs. Using an optimized protocol, full-scale runs according to FDA current Good Manufacturing Practice (cGMP) standards were completed with immediate filtration of blood obtained from donors participating in our study. ResultsForward flushing of the filter removed 85% to 95% of residual RBCs and platelets. When backward flushed with 800 mL, 95% of the WBCs recovered were contained in the first 400 mL. The number of recovered WBCs was in the range of 166–211 million/100 mL filtered blood. Subpopulations of WBCs recovered from the LRFs were in the same proportion as the donors' whole blood. Viability of recovered WBCs was 96–99%. Exogenous rabbit antibodies bound well to the recovered WBCs and were retained for at least 5 h without significant reduction. Three full scale runs of WBCs recovered from donor blood filtered through the LRF met all FDA specification of sterility, endotoxin levels, viability and stability. ConclusionUsing LRFs, high quality clinical grade WBCs are readily obtained in quantities of 0.2 to 1.2 billion cells from 100 mL to 450 mL (1 unit) of whole blood.

A Quality Approach to Reducing the Occurrence of Occluded Leukocyte Reduction Filters During Platelet Transfusion.

In 2019, an increase in clotted platelet filter occurrences was noted with the implementation of new leukocyte reduction filters through a volumetric pump. Occluded platelet filters contribute to delays in platelet transfusions, additional nursing workflows, and potential wastage of platelets, leading to staff and patient dissatisfaction. Direct observation of nursing practice with priming platelet filters identified opportunities for improvement. Education was designed incorporating manufacturer recommendations with results of the observations. Nursing education was disseminated through small group sessions, one-to-one teaching, tip sheets, and an e-learning video. Nursing education interventions resulted in a 170% reduction in the reported monthly filter occlusion rate. Engagement of nurses in quality improvement processes and collaboration across departments led to a sustained decrease in the clotted platelet filters.

Influence of a cell salvage washing system and leukocyte reduction filtration on bacterial contamination of canine whole blood ex vivo.

To determine the ability of cell salvage washing and leukoreduction filtration to remove bacterial contamination from canine whole blood. Ex vivo nested cohort study. Commercially purchased fresh canine whole blood (n = 33 units). Commercially obtained canine whole blood was inoculated with known concentrations of one of three species of bacteria, Escherichia coli (ATCC 25922), Staphylococcus pseudintermedius (quality control strain; Texas A&M University), or Pseudomonas aeruginosa (ATCC 27853). Negative controls were inoculated with sterile saline. The inoculated blood was processed through a cell salvage system and filtered through a series of two leukocyte reduction filters. Samples were aseptically collected at five points during processing (inoculum, prewash, postwash, post-first filtration, and post-second filtration) for bacterial enumeration. Bacterial concentrations were reduced by 85.2%, 91.5%, and 93.9% for E coli, S pseudintermedius, and P aeruginosa, respectively, after washing (P < .0001), and bacterial concentrations were reduced by 99.9%, 100%, and 100%, respectively, after the first filtration (P < .0001). After the second filtration, none of the three species of bacteria could be isolated (100% reduction). No bacterial growth was obtained from negative controls throughout the study. The type of bacteria (P = .29) did not allow prediction of bacterial reduction. Cell salvage washing combined with leukoreduction filtration eliminated bacterial contamination of whole dog blood (P < .0001). Cell salvage washing and leukoreduction filtration could be applied to intraoperative autotransfusion in clinical animals, especially those treated for trauma or hemorrhage with concurrent bacterial contamination.

Abstract A25: Differentiation of human naive T cells to various effector memory cell subtypes correlates with increased binding of the B subunit of Type-IIb heat-labile enterotoxin (LT-IIb-B5) to its cognate ganglioside receptors

Abstract The initial antigenic activation of T cells involves localization of the T-cell receptor to lipid rafts, of which gangliosides are major components. To understand the role of lipid rafts in the activation and differentiation of CD4+ and CD8+ T cells, it is necessary to dissect the ganglioside composition in each respective T-cell subset. In the present study, we used the B subunits of type-II heat-labile enterotoxins (LT-IIa-B5, LT-IIb-B5 and LT-IIc-B5), which possess defined ganglioside-binding specificities, as molecular probes to dissect the membrane ganglioside composition of human T cell subsets. Peripheral blood mononuclear cells isolated from leukocyte reduction filters by Ficoll density gradient centrifugation were stained with recombinant LT-IIa-B5, LT-IIb-B5, mutant LT-IIb-B5(T13I) or LT-IIc-B5 and with monoclonal antibodies to CD4, CD8, CD27, CD45RA, CD45RO and CD62L followed by flow cytometric analysis. Our results show that ligands for LT-IIa (gangliosides GD1b, GM1, and GT-1b), LT-IIb (gangliosides GD1a, GT1b and GM2), and LT-IIc (gangliosides GM1, GM2, and GM3) are increasingly expressed during differentiation from naïve (CD4+ or CD8+CD45RO-CD27+) to memory (CD4+ or CD8+CD45RO+CD27+) T cells, and that discrete subsets of central memory (CD4+ or CD8+CD45RA-CD62L+), effector memory (CD4+ or CD8+CD45RA-CD62L-), and terminally differentiated effector memory (CD4+ or CD8+CD45RO+CD27-) T cells express the highest ganglioside levels, particularly of LT-IIb-ligands. On the other hand, mutant LT-IIb-B5(T13I), which had negligible binding in vitro to gangliosides GD1a, GT1b, and GM2, exhibited no detectable binding to naive or central memory T cells, but significantly bound subsets of terminally differentiated effector memory (CD4+ and CD8+) T cells. Our results suggest an important role for gangliosides GD1b and GM1 in naive T-cell responses, while central memory, effector memory, and terminally differentiated effector memory T-cell responses may be more dependent upon gangliosides GD1a and GT1b. Furthermore, the lymphocyte-binding activities of LT-IIb-B5(T13I) confirm that its parental B-pentameter essentially recognizes gangliosides GD1a, GT1b, and GM2 on T cells and suggest that LT-IIb-B5 (T13I) may bind to one or more unknown receptor(s) expressed on subsets of terminally differentiated effector memory (CD4+ and CD8+) T cells. Citation Format: Taylor A. Johnson, Madison K. Ritter, Mary-Peyton A. Knapp, Robert O. Rainer, Nathalie D. King-Lyons, Terry D. Connell, Sergio Arce. Differentiation of human naive T cells to various effector memory cell subtypes correlates with increased binding of the B subunit of Type-IIb heat-labile enterotoxin (LT-IIb-B5) to its cognate ganglioside receptors [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2019 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(3 Suppl):Abstract nr A25.

Interval analysis of blood filtration efficacy in novel device for autotransfusion in postpartum hemorrhage

Postpartum haemorrhage (PPH), the leading cause of maternal mortality, is particularly problematic in low resource settings where access to safe blood supplies and definitive medical treatment is limited. We describe the continued development of an autotransfusion device designed to treat PPH by collection, filtration and infusion of maternal blood. Previous study has demonstrated that the device effectively moves blood through a filtration apparatus and removes up to 97% of aerobic bacteria but had poor anaerobic bacteria reduction. In this study, we investigate the filtration efficacy of the device using configurations comprised of three different leukocyte depletion filter designs: the Pall Leukoguard RS leukocyte reduction filter (PLRF), the Haemonetics BPF4™ (BPF4) leukocyte reduction filter, and the Haemonetics SCRC Leukotrap® (SCRC) filter. All configurations performed well with reductions ranging from 49 to 98%. Configurations containing 2 Haemonetics SCRC Leukotrap®filters (configuration 5 and 6) consistently reduced anaerobic bacteria by at least 73%. These results indicate that utilising a combination of SCRC and PLRF filters confers a high level of microbial filtration with improved removal of anaerobic organisms.

A zwitterionic interpenetrating network for improving the blood compatibility of polypropylene membranes applied to leukodepletion

Although widely used in blood-contacting devices, polypropylene (PP) membranes are prone to biofouling by plasma proteins and blood cells. The present study explores the effect of a surface zwitterionization process on the improvement of the biofouling resistance of PP membranes for leukocyte reduction filters. The modification strategy consists in forming an interpenetrating network of poly(glycidyl methacrylate-co-sulfobetaine methacrylate) (poly(GMA-co-SBMA) around the fibers of coated PP membranes, using a cross-linking agent: ethylenediamine (EDA). It is shown that with EDA, a range of poly(GMA-co-SBMA) concentration (1–5 mg/mL) leads to a 0°-water contact angle and high hydration of the networks without affecting the intrinsic porous structure of the material. Besides, the related membranes show excellent resistance to biofouling by Escherichia coli, fibrinogen, leukocytes, erythrocytes, thrombocytes and cells from whole blood with reductions in adsorption of 97%, 86%, 90%, 95%, 97% and 91%, respectively, compared to unmodified PP. Used in whole blood filtration, it is demonstrated that in the best conditions (5 mg/mL copolymer, with EDA), leukocytes can be efficiently removed (>99.99%) without altering the erythrocytes concentration in the permeate, and that leukodepletion is more efficient than that measured with a commercial hydrophilic PP blood filter (about 50% retention). Physical retention of leukocytes is only efficient if the membrane material is anti-biofouling, and so, does not interact with other blood components able to trigger leukocyte attachment/deformation.

Leukocyte reduction filters: A source of peripheral blood leukocytes for research and drug production

Leukocyte reduction filters: A source of peripheral blood leukocytes for research and drug production

A novel obstetric medical device designed for autotransfusion of blood in life threatening postpartum haemorrhage

Postpartum haemorrhage (PPH) is an obstetric emergency caused by excessive blood loss after delivery, which is the leading cause of maternal mortality worldwide. PPH can lead to volume depletion, hypovolemic shock, anaemia and ultimately death. The prevalence of PPH is disproportionately higher in low resource settings where there is limited access to skilled medical care and safe blood supplies. Current management strategies target both prevention and treatment of PPH however no alternatives currently exist to address the lack of safe blood supplies which are considered essential in emergency obstetrical care. Autotransfusion is used to salvage blood loss in a variety of clinical settings but has never been used in the context of vaginal delivery. We describe the development and testing of a novel device for the collection, filtration and autotransfusion of blood lost due to PPH. The prototype device is inexpensive and easily operated so that it may be practically deployed in low resource settings. The device is comprised of a blood collection drape, a pump apparatus, three leukocyte reduction filters and a reservoir for filtered blood. Preliminary testing demonstrates efficacy of microbial load reduction of up to 97.3%. To reduce cost and improve safety, the device is modular in design such that the drape, tubing, filters and transfusion bag may be stored sterile, used once and discarded; while the pump apparatus may be used indefinitely without the need for sterilisation. Preliminary results indicate the device confers a low cost and potentially effective means of collecting, pumping, filtering and returning blood to a patient following PPH in settings that lack safe blood supplies. This device shows promise as a method of stabilising patients suffering of PPH in low resource settings until definitive treatment is rendered with the ultimate goal of reducing maternal mortality globally.

RBC Adhesive Capacity Is Essential for Efficient 'Immune Adherence Clearance' and Provide a Generic Target to Deplete Pathogens from Septic Patients

Sepsis is a life threatening organ dysfunction caused by a dysregulated host response to infection. It is a global health care problem and the leading cause of death in ICU patients. A rather unknown but effective mechanism to protect ourselves from such pathogen invasion is immune-adherence clearance (IAC). During IAC pathogens (including bacteria, fungi and viruses) can bind to red blood cells (RBCs) through complement opsonization and subsequent binding to complement receptor 1 (CR1, CD35) expressed on their cell surface. After binding of the pathogen to CR1, the RBCs deliver the pathogens to macrophages of the spleen and liver, where they are phagocytosed and degraded.To study the underlying mechanisms of IAC in more detail, we have developed an assay to monitor the transfer of opsonized pathogens bound to RBCs to human monocytes and/or macrophages under flow conditions, using confocal microscopy. The transfer of a variety of different pathogens, including S. aureus, E. coli and C. albicans, was studied in this assay. When looking at the transfer process in detail, it was noticed that RBC attach to the phagocyte prior to the transfer and remain attached shortly after the transfer, suggesting that RBC might be interacting with phagocytes through adhesion molecules such as integrins to establish firm binding between these two cell types. To test this hypothesis several adhesion molecules, on the phagocytes as well as on the RBC, were blocked by monoclonal antibodies and IAC was quantified. First, complement receptor 3 (CR3, amb2 CD11b/CD18 integrin) an important receptor for adhesion, migration and phagocytosis was blocked by monoclonal antibodies on the phagocytes, after which bacterial transfer was impaired. This indicated that CR3 is crucial for efficient IAC. To confirm the involvement of CR3 in IAC, we analyzed the monocytes of a known LAD-1 patient. This rare immunodeficiency is characterized by an inherited molecular defect of the β2integrin subunit (CD18) which results in impaired adhesion and migration of the patient’s leukocytes and clinically manifests in recurrent infections. Our results showed a highly reduced interaction between the phagocytes and the RBCs, resulting in a decrease in bacterial transfer of >70%.Next, we tested the effects of blocking antibodies directed against several RBC adhesion molecules on the transfer process. When blocking CD147 (Basigin, Ok blood group) and ICAM-4 (CD242, Landsteiner-Wiener), but not Glycophorin A (GPA, CD235a) on the RBC the transfer process was largely inhibited. These findings demonstrate the involvement of direct cell-cell interactions between RBC and macrophages in IAC and provide evidence that RBC adopt a "sticky" phenotype after binding a pathogen through CR1, which enables phagocytes to bind them under flow. We anticipated that blood bank filters (currently used for leukocyte depletion) might be used to bind and filter RBC-pathogen complexes from blood due to their "sticky" phenotype. This was found to be possible in a series of experiments, not only using in vitrogenerated RBC-pathogen complexes, but also using blood from septic patients. Filtration using a standard leukocyte reduction filter showed reduction of RBC-pathogen complexes close to 100%, independent of the type of pathogen. We foresee that this knowledge can be used to develop a generic approach to deplete RBCs carrying pathogens specifically from the blood stream, and thereby filter RBC-pathogen complexes from the blood of patients suffering from sepsis. DisclosuresNo relevant conflicts of interest to declare.

Effects of universal vs bedside leukoreductions on the alloimmunization to platelets and the platelet transfusion refractoriness

BackgroundMultiple platelet exposure induces anti-HLA and/or anti-HPA antibody production, which may cause platelet transfusion refractoriness (PTR). In Japan, the universal pre-storage leukocyte reduction (ULR) was fully implemented since 2006, but prior to ULR, in our institution, leukocyte reduction filters were routinely used at the bedside (bedside leukoreduction, BSLR) for all onco-hematological patients receiving multiple platelet transfusions. ObjectiveWe retrospectively compared patients receiving platelet transfusions in the era of ULR with those of BSLR era. Materials and methodsPatients of the BSLR group (409 cases) and the ULR group (586 cases) were compared in terms of alloimmunization and immunological PTR. The clinico-pathological features, including gender, history of pregnancy, number of exposed transfusion donors, periods of transfusion, and prior stem cell transplantation were compared, and the risk factors of alloimmunization were determined. ResultsThe antibody detection rate was significantly higher in the ULR compared to BSLR group (8.7% vs. 5.4%), as well as the immunological PTR rate (7.3% vs. 3.2%). By the multivariate analysis, female gender and the number of platelet donor exposure, but not universal leukoreduction or transfusion period, were found to be the risk factors strongly associated with alloantibody formation. ConclusionAlthough ULR may be superior to BSLR in terms of preventing non-hemolytic transfusion reactions, BSLR was found to be as effective as ULR in terms of preventing platelet alloimmunization and refractoriness. Thus, BSLR should be actively indicated as a realistic alternative in developing countries, before the universal leukoreduction is fully implemented.

The effect of leukocyte reduction filters on inflammatory mediator release during coronary artery bypass grafting

Extracorporeal circulation used during coronary artery bypass grafting triggers systemic inflammatory response with neutrophil activation which adversely affects ischaemic/reperfused myocardium. One method of myocardial protection during cardiac surgery is the use of blood cardioplegia. Its protective effect is related to cardiac cooling and metabolism reduction, oxygen supply from erythrocytes, and reactive oxygen species scavenging. However, blood cardioplegia is also associated with myocardial damage induced by undesirable morphotic blood elements. To evaluate the effect of the use of leukocyte reduction filters on the activity of polymorphonuclear neutrophils (PMN) in patients undergoing surgical myocardial revascularisation. PMN activity was evaluated based on measurements of plasma activity of granulocyte enzymes, lysozyme and beta-glucuronidase. We studied 40 patients who underwent myocardial revascularisation using extracorporeal circulation. Patients were randomly assigned to two equal groups: in Group I, blood cardioplegia was administered using leukocyte reduction filters, and in Group II, leukocyte reduction filters were not used for blood cardioplegia. Measurements were performed in plasma of arterial and coronary sinus blood samples collected before aortic clamping, immediately after unclamping, and after 25 min of reperfusion. In addition, blood cardioplegic solution samples were collected in Group I from the lines proximal and distal to the filter during first and last administration. Plasma levels of lysozyme and beta-glucuronidase were determined using previously described methods. We found a significant decrease in PMN count in filtered blood cardioplegic solution during its first administration (0.27 ± 0.07 G/L) compared to samples collected before filter passage (1.73 ± 0.049 G/L). Also during last administration, PMN count in filtered blood cardioplegic solution was decreased compared to samples collected before filter passage (0.66 ± 0.35 G/L vs. 3.64 ± 1.14 G/L, respectively). Significantly lower (p < 0.02) plasma beta-glucuronidase levels were found in arterial blood samples in Group I compared to Group II (5.59 ± 1.63 μg/mL immediately after aortic unclamping and 6.59 ± 1.98 μg/mL after 25 min of reperfusion in Group I vs. 10.19 ± 2.66 and 12.83 ± 1.88 μg/mL, respectively, in Group II). Beta-glucuronidase levels in coronary sinus blood samples collected after aortic unclamping and at the end of reperfusion were significantly higher in Group II compared to Group I (p < 0.04). In Group I, plasma lysozyme levels in arterial and venous blood samples did not show significant changes during the surgery. In contrast, plasma lysozyme level in coronary sinus blood samples at the end of reperfusion in Group II was significantly higher compared to that in pre-clamping samples (p < 0.014). With the use of leukocyte reduction filters, we found significantly lower beta-glucuronidase levels in arterial and coronary sinus blood samples. These findings seem to confirm reduced PMN activation and/or reduced myocardial infiltration by activated PMN. Plasma levels of lysozyme, a characteristic product of PMN degranulation, did not show significant differences between the study groups.

Use of microaggregate blood filters instead of leukocyte reduction filters to purify salvaged, autologous blood for re-transfusion during obstetric surgery

To the Editor: Intraoperative, salvaged, autologous blood re-transfusions are especially useful to treat profuse hemorrhage that occurs during obstetric surgeries [1]. A prominent concern with such autotransfusions is the risk that the relatively large pore size (170–260 μm) of standard blood transfusion filters may not eliminate all amniotic and fetal materials and other contaminants from the salvaged, autologous blood where they can cause amniotic fluid embolization (AFE). Use of leukocyte reduction filters (LRFs) with 10–50 μm pore size during salvage of autologous blood in cesarean sections appears to be able to eliminate amniotic and fetal particulate substances such as fetal squamous cells [2], and thereby prevent AFE. Intraoperative autotransfusions with LRFs, therefore, represent a promising technique for the treatment of profuse hemorrhage in obstetric surgeries. However, since 2007, the Japanese Red Cross Blood Center has provided pre-storage leukocyte-reduced red cell concentrate containing a citrate–phosphate–dextrose solution instead of an acid–citrate–dextrose solution as anticoagulant in which the leukocytes were reduced soon after collection. LRFs have not been made since 2006, and have not been supplied since 2009 by Japanese manufacturers. Microaggregate blood filters (MBFs) with 10–40 μm pore size are able to eliminate larger-diameter, retained, blood component microaggregate materials and non-blood, particulate matter that is potentially harmful to the recipients. In other words, MBFs assure the patient protection from microaggregate materials, clots, and particulate debris that can cause pulmonary embolization [3]. We managed a case with a re-transfusion of salvaged, autologous blood using a Pall SQ40® (Pall, Tokyo, Japan) MBF with 40 μm pore size instead of LRF for massive hemorrhage during obstetric surgery [4]. Finally, abortion and total abdominal hysterectomy were performed and no AFE or other complications occurred. The Pall SQ40® MBF is a free-flow, low priming volume device which provides a 40 μm rated filter and media pleating for the elimination of potentially harmful blood component microaggregates and non-blood component particulate matter [5]. Pall’s 40 μm rated polyester screen media is process-controlled and monitored to ensure uniformity of pore size to assure maximum patient protection from microaggregates, clots, and particulate debris. Further, screen-type MBFs are able to maintain a relatively high speed of transfusion, because of their larger total filter area. The total filter area of Pall’s screen-type MBF (160 cm2) provides up to twelve times the typical first surface area of a depth-type MBF. This feature reduces the number of administration set changes required for rapid transfusion, particularly for blood components with a large debris load such as salvaged blood components. In massive obstetric hemorrhage, rapid re-transfusions are required for resuscitation. Since LRFs limit the speed of transfusion, it is sometimes necessary to suspend or forego the use of an LRF, and to use screen-type MBFs, instead, in order to increase the speed of transfusion. In conclusion, MBFs instead of LRFs should be available and ready to use to purify salvaged, autologous blood for re-transfusion to treat profuse hemorrhage during obstetric surgeries, and to prevent AFE.

A selective cytopheretic inhibitory device for use during cardiopulmonary bypass surgery

Systemic inflammatory response syndrome (SIRS) can occur in association with cardiopulmonary bypass (CPB) surgery, resulting in multiple organ dysfunction (MOD). Activated neutrophils have been implicated as major inciting factors in this process. Neutrophil-depleting filters incorporated within the extracorporeal blood circuit during CPB have been developed and evaluated, with inconsistent clinical results. A novel, biomimetic, selective cytopheretic device (SCD) was tested in vitro within a blood circuit to assess safety and interactions with blood components and further evaluated ex vivo in a bovine model of CPB surgery during ventricular assist device implantation. In vitro blood circuit studies demonstrated that the SCD reduces circulating neutrophils while maintaining low rates of hemolysis compared to current leukocyte-reduction filters. In the bovine CPB model, animals without SCD treatment (No SCD) demonstrated an increase in circulating white blood cell (WBC) and neutrophil counts, steadily increasing throughout CPB. SCD with only systemic heparin anticoagulation (SCD-H) acutely reduced neutrophils for the first 2 hrs of CPB, but followed with a greater than 6-fold increase in neutrophil counts. SCD treatment with regional citrate anticoagulation along the SCD circuit (SCD-C) reduced systemic neutrophil counts throughout 4 hrs of CPB despite lower amounts of eluted cells from the SCD. When analyzed for immature neutrophils, the control and SCD-H showed increasing counts at later time-points, not seen in the SCD-C group, suggesting a more complex mechanism of action than simple leukoreduction. These results suggest that SCD-C therapy may disrupt the systemic leukocyte response during CPB, leading to improved outcomes for CPB-mediated MOD.

Comparison of two leukocyte reduction filters for whole blood derived platelets

BackgroundLeukocyte reduction filters are widely used for platelet transfusion therapy, and effective leukocyte removal is mandatory for transfusion safety. We evaluated both the performance of leukocyte reduction filters for platelets and the effect of filtration on platelet function. MethodsA total of 100 pooled products (eight platelet concentrates were randomly pooled for each product) were used in this study: 50 were filtered by BioP-plus (Fresenius Kabi AG, Homburg, Germany) and 50 by PXL-8 (Pall Corporation, East Hills, NY, USA). Leukocyte reduction, platelet recovery, and filtration time were evaluated in each leukocyte reduction filter. Platelet aggregation responses to thrombin receptor activation peptide stimulation were compared in pre- and post-filtration products using impedance aggregometry (Multiplate Analyzer, Dynabyte Medical, Munich, Germany). ResultsLeukocyte counts were uniformly less than 8.3×105 in all the post-filtration products, except one filtered by the PXL-8. Leukocyte reduction was 99.1% for BioP-plus and 99.7% for PXL-8, and platelet recovery was 84.2% for the BioP-plus and 86.7% for PXL-8. Filtration time of the BioP-plus was significantly shorter than that of PXL-8. Post-filtration platelet aggregation tended to decrease in both filters, showing no difference between them. ConclusionsBoth BioP-plus and PXL-8 leukocyte reduction filters for platelets performed well with effective leukocyte reduction and satisfactory platelet recovery. Although platelet function was decreased after filtration procedures, its clinical relevance is uncertain.