Leukocyte Removal Research Articles

Does Systemic Leukocyte Filtration Affect Perioperative Hemorrhage in Cardiac Surgery? A Systematic Review and Meta-Analysis

Cardiopulmonary bypass causes a systemic inflammatory reaction. Activation of leukocytes is an important part of this process, and is known to directly contribute to the development of postoperative coagulopathy, and thus hemorrhage. The removal of leukocytes from the cardiopulmonary bypass circulation, using specialized filters, has been proposed as one method for attenuating this inflammatory response. However, there is no consensus on its effectiveness. We used meta-analytical techniques to systematically assess the literature reporting on the potential effect of systemic leukofiltration on perioperative hemorrhage. Random effects modeling was used to calculate overall estimate, and heterogeneity was assessed. Systemic leukofiltration made no significant impact on chest tube drainage in the first 24 hours (weighted mean difference [WMD], x23.9 ml; 95% confidence interval [CI], x95.48-47.61; p = 0.51) or on the total packed red cell transfusion requirements of each patient (WMD, 7.84 ml; 95% CI, x80.13-95.81; p = 0.86). The studies performed in this area thus far are highly heterogeneous, due in part to relatively poor-quality design and inadequate matching of their study groups. Although further high-quality trials on systemic leukofiltration may be appropriate, other strategies to reduce the coagulopathy associated with cardiopulmonary bypass should be sought and evaluated.

Extracorporeal leukocyte removal therapy for patients with ulcerative colitis

The purpose of the present paper was to investigate efficacy of leukocytapheresis (LCAP) or granulocytapheresis (GCAP) in pediatric patients with ulcerative colitis (UC), including reduction of the total dose and side-effects of corticosteroids. Courses of five Japanese adolescents with UC were analyzed. Four patients had recurrent UC with repeated remissions and exacerbations despite therapy including 5-aminosalicylic acid in combination with a corticosteroid. The other patient had a first attack. Effectiveness of adding LCAP or GCAP was assessed with regard to short-term changes in clinical activity, complications, and longer-term outcome. Clinical improvement was attained in three patients, while the other two did not improve and underwent colectomy. One of the two patients had moderately severe complications from LCAP and showed increased clinical activity during LCAP. The other, who began therapy with LCAP alone, had moderate improvement only after addition of a corticosteroid. Additional studies are needed to determine optimum timing of LCAP or GCAP and initiation of remission-maintenance therapy.

Inflammatory Cells in Renal Injury and Repair

Renal inflammation may result from a myriad of insults and often is characterized by the presence of infiltrating inflammatory leukocytes within the glomerulus or tubulointerstitium. Accumulating evidence indicates that infiltrating leukocytes are key players in the induction of renal injury. Although renal inflammation often is followed by the development of fibrosis with loss of renal function, it can resolve. Resolution may be spontaneous as in poststreptococcal glomerulonephritis or after the administration of effective treatment such as immunosuppressive agents. The mechanisms and cells underlying the resolution process and the exact temporal sequence remains uncertain at present but likely involves the removal of injurious leukocytes, the down-regulation of immune responses, and the alteration of the phenotype of infiltrating macrophages from proinflammatory to prorepair. In this review we examine the role of leukocytes in both renal inflammation and repair.

Blood cell separation using crosslinkable copolymers containing N,N‐dimethylacrylamide

AbstractAmphiphilic copolymers using hydrophilic N,N‐dimethylacrylamide (DMA), hydrophobic methyl methacrylate (MMA) and a crosslinkable monomer, 3‐methacryloyloxypropyl trimethoxysilane (MTSi), were synthesized and evaluated as coating materials for leukocyte removal filters for whole blood. When filters composed of non‐woven fabrics were coated with crosslinked synthesized copolymers, the elution ratios of the copolymers to water were adequately low because of the crosslinking with trimethoxysilane groups of MTSi units in the copolymers. Filters coated with crosslinked poly(DMA‐co‐MTSi) having a 0.96 mole fraction of DMA units showed a 0.35 ± 0.44% platelet permeation ratio and a logarithmic reduction of 4.0 ± 0.68 for leukocytes. On the other hand, an increase in the content of MMA units in the DMA‐containing copolymers improved the permeation ratio of the platelets dramatically. Filters coated with crosslinked poly(DMA‐co‐MMA‐co‐MTSi) containing a 0.39 mole fraction of MMA units and a 0.58 mole fraction of DMA units showed an 86 ± 3.0% platelet permeation ratio and a logarithmic reduction of 2.1 ± 1.2 for leukocytes. This indicates that an adequate content of hydrophobic monomer units, such as MMA units, is necessary for effective platelet permeation. Copyright © 2007 John Wiley & Sons, Ltd.

Hypermethylation of RASSF1A in Human and Rhesus Placentas

The pseudomalignant nature of the placenta prompted us to search for tumor suppressor gene hypermethylation, a phenomenon widely reported in cancer, in the human placenta. Nine tumor suppressor genes were studied. Hypermethylation of the Ras association domain family 1 A (RASSF1A) gene was found in human placentas from all three trimesters of pregnancy but was absent in other fetal tissues. Hypermethylation of Rassf1 was similarly observed in placentas from the rhesus monkey but not the mouse. An inverse relationship between RASSF1A promoter methylation and gene expression was demonstrated by bisulfite sequencing of microdissected placental cells and immunohistochemical staining of placental tissue sections using an anti-RASSF1A antibody. Treatment of choriocarcinoma cell lines, JAR and JEG3, by 5-aza-2'-deoxycytidine and trichostatin A led to reduction in RASSF1A methylation but increased expression. These observations extend the analogy between the primate placenta and malignant tumors to the epigenetic level.

The effects of various leukocyte filtration strategies in cardiac surgery

It is known that cardiopulmonary bypass causes an inflammatory reaction with an associated morbidity and mortality. Several anti-inflammatory strategies have been implemented to reduce this response, including leukocyte removal from the circulation using specialised filters. The aim of this study is to systematically review the available evidence on leukocyte filtration in cardiac surgery, focusing on its effect on systemic inflammation and whether this has influenced clinical outcomes. Five electronic databases were systematically searched for studies reporting the effect of leukocyte filtration at any point within the cardiopulmonary bypass circuit in humans. Reference lists of all identified studies were checked for any missing publications. Two authors independently extracted the data from the included studies. Whilst systemic leukodepleting filters do not appear to consistently lower leukocyte counts, they may preferentially remove activated leukocytes. Small improvements in early post-operative lung function in patients receiving systemic leukodepletion have been reported, but this does not lead to reduced hospital stay or decreased mortality. There is substantial evidence that cardioplegic leukocyte filtration attenuates the reperfusion injury at a cellular level, but this has not been translated into clinical improvements. Finally, whilst various strategies involving multiple leukocyte filters, or the incorporation of pharmacological agents into leukocyte-depleting protocols have been evaluated, the current available results are not conclusive. Our study suggests that there is not enough high quality or consistent evidence to draw guidelines regarding the use of leukocyte-depleting filters within routine cardiac surgical practice.

免疫活性制御酸素（ＩＤＯ）による白血球除去フィルターの性能評価

免疫活性制御酸素（ＩＤＯ）による白血球除去フィルターの性能評価

Flow Analysis System for Leukocyte Removal Column

Flow Analysis System for Leukocyte Removal Column

Extracorporeal elimination of TNF-α-producing CD14dullCD16+ monocytes in leukocytapheresis therapy for ulcerative colitis

In recent years leukocytapheresis using a leukocyte removal filter (known as lymphocytapheresis, LCAP) has been applied to the treatment of various autoimmune diseases including ulcerative colitis (UC). In the present study we aimed to clarify how LCAP therapy modifies inflammatory responses by modulating circulating TNF-alpha-producing monocytes. Mononuclear cells were obtained from blood before and after the first treatment, and the expression profiles of various immune cells (naive versus. memory, regulatory CD4(+)CD25(bright) versus non-regulatory CD4(+)CD25(-) T cells, and CD14(+)CD16(-) versus CD14(dull)CD16(+) monocytes) were assessed. To evaluate immunological differences between CD14(+)CD16(-) and CD14(dull)CD16(+) monocytes, the expression of TNF-alpha, IL-6, IL-12, IL-10, IL-18, surface toll-like receptor 2 (TLR2), TLR4, and other activation markers including HLA-DR, CD80 and CD86, as well as cytokine profiles, were analyzed. LCAP treatment selectively removed CD14(dull)CD16(+) monocytes, which preferentially produce TNF-alpha and IL-12 and express HLA-DR, CD80, CD86, and TLR2, compared with the major fraction of CD14(+)CD16(-) monocytes, which conversely produce a higher amount of IL-10. In addition, the CD4(+)CD45RO(+)CD62L(-)/CD4(+)CD45RO(+)CD62L(+) ratio was significantly lower after LCAP therapy. However, the CD4(+)CD25(bright)/total CD4(+) ratio did not change. The present findings revealed the real target of proinflammatory CD14(dull)CD16(+) monocytes removed during LCAP treatment of UC and that LCAP might be used as an extracorporeal anti-TNF-alpha therapy, expanding the clinical applications of this procedure to include the treatment of Crohn's disease.

Current strategies to prevent transmission of prions by human plasma derivatives

Protein products prepared from pooled human plasma are an essential class of therapeutics used mostly to control bleeding and/or immunological disorders. Because of the human origin of the starting material, there is a risk that these products may possibly transmit prions causing variant Creutzfeldt–Jakob disease (vCJD). No case of transmission of prions by plasma products has been observed. Case-by-case measures implemented in various countries, and several technical factors may contribute, to various degrees, to the prevention of the risk of transmission of prions by plasma products. Those measures include (a) the epidemiological surveillance of population in countries with cases of vCJD and/or bovine spongiform encephalopathies (BSE), (b) the deferral of blood donors who traveled or resided, for specific periods of time, to countries with BSE, or who received transfusion or tissue transplant, (c) the removal of leucocytes in plasma used for fractionation, and, last but not least, (d) the removal of the prion agents during the complex industrial fractionation process used to prepare plasma products. Numerous experimental infectivity studies, involving the spiking of brain-derived infectious materials, have demonstrated that several fractionation steps, in particular ethanol fractionation, depth filtration, and chromatography, can remove several logs of prions. Removal is explained by the distinct hydrophobic and aggregative properties of the prion proteins. In addition, nanofiltration using multi-layer membranes of 75 nm or smaller, which is commonly used for removing viruses from coagulation factors and immunoglobulins products, can remove more than 3–5 logs of spiked prions, presumably by size-exclusion and trapping mechanisms. Therefore, the risk of transmission of vCJD by human plasma products appears remote, but caution should prevail since the biochemical nature of the infectious agent in human blood is still unknown.

Leukocyte removal therapy before surgery in ulcerative colitis

Leukocyte removal therapy before surgery in ulcerative colitis

Leukocyte removal therapy for ulcerative colitis does not affect postoperative complications

We investigated the incidence of postoperative complications in patients treated with or without preoperative leukocyte removal therapy (LRT). The case notes of 387 patients with ulcerative colitis (UC) who underwent surgical intervention were retrospectively reviewed. One hundred nine patients were treated with LRT within 8 weeks before surgery (LRT group), and 278 had not received LRT since at least 8 weeks before surgery (without LRT group). We reviewed the postoperative complications according to type of initial operation. Of the patients who underwent an ileal J-pouch anal anastomosis (IPAA) without an ileostomy, 3 (6.5%) in the LRT group developed pouch-related complications (PRC), while 11 (7.5%) in the without LRT group developed PRC. The overall postoperative complication rates were 28.3% in the LRT group and 21.8% in the without LRT group. For patients who underwent an IPAA with an ileostomy, the overall rates of postoperative complications were 39.1% in the LRT group and 31.8% in the without LRT group. Among those undergoing a total colectomy, 33.3% in the LRT group and 18.2% in the without LRT group had postoperative complications. No statistically significant differences were demonstrated between the two groups with respect to postoperative complications. Our results suggest that preoperative LRT does not influence the rate of postoperative complications in UC patients.

Blood cell separation using amphiphilic copolymers containing N,N‐dimethylacrylamide

To develop leukocyte removal filters effective for whole blood, amphiphilic copolymers based on N,N-dimethylacrylamide were synthesized and evaluated as coating materials for poly(ethylene terephthalate) filters. The copolymers with methyl methacrylate or 2-hydroxypropyl methacrylate as a comonomer showed higher platelet permeation ratios (more than 90%) than that of the copolymer with n-butyl methacrylate, though the logarithmic reductions of leukocytes by these copolymers were less than four. An increase in the platelet permeation for whole blood tended to increase the leukocyte permeation. The permeation of both platelets and leukocytes increased with the amount of copolymer coated on the filters because of the change in the physical properties such as the average pore size, total surface area, and total pore volume of coated filters. These results confirm that both the chemical and physical properties of the filters play important roles to control the permeation behavior.

Investigation of the Clinical Effect of Large Volume Leukocytapheresis on Methotrexate‐Resistant Rheumatoid Arthritis

Leukocytapheresis (LCAP) is already being used in a clinical setting for the treatment of autoimmune diseases such as inflammatory bowel disease and rheumatoid arthritis, and it has been reported to be effective. However, it is totally or partially ineffective in some patients, which has forced clinicians to rethink therapeutic strategies and concurrent treatment. With the aim of enhancing the therapeutic effect, we carried out large volume leukocytapheresis, with a throughput of 5000 mL instead of the 3000-mL throughput of conventional leukocytapheresis in nine patients with rheumatoid arthritis resistant to methotrexate treatment. Using Cellsorba, the column filled with the unwoven fabric made of the polyethylene phthalate, a leukocyte removal filter, large volume leukocytapheresis was carried out once a week for a total of five sessions. The observation period was the 12-week period following completion of treatment. The American College of Rheumatology (ACR) core set was used for assessment of efficacy. Eight weeks after completion of treatment, a 20% improvement in ACR was observed in 77.8% (7/9) of subjects, a 50% improvement in ACR was seen in 55.6% (5/9) of subjects, and a 70% improvement in ACR was observed in 22.2% (2/9) of subjects. C-reactive protein decreased gradually as treatment progressed, and a significant decrease was observed 4 weeks after completion of treatment. The fact that some subjects had an ACR70 response, few reports of which are observed in the case of conventional leukocytapheresis, and the fact that the effect continued up to 12 weeks after completion of treatment suggests that the degree and duration of the effect of large volume leukocytapheresis might be longer than those of conventional leukocytapheresis.

Clinical Efficacy and Biocompatibility of Three Different Leukocyte and Fat Removal Filters During Cardiac Surgery

Activated leukocytes and fat particles are associated with organ injury after a cardiac surgery. Filters are currently used to remove either leukocytes or fat particles. A novel approach with a filter that combines leukocyte and fat removal might be clinically useful. As it is not known which type of filter has a good and safe performance in both leukocyte and fat removal, we measured in this study the leukocyte and fat removal properties and the biocompatibility of three different filters. We used six Pall RS1 (Pall, Portsmouth, England) leukocyte removal filters, six Pall LipiGuard fat removal filters, and six Fresenius Biofil 02 (Fresenius, Emmer-Compascuum, The Netherlands) leukocyte removal filters and measured the passage times of 500 and 1000 mL of residual heart-lung machine blood. We determined the circulating leukocyte and platelet counts, and total hemoglobin, triglyceride, and free fatty acid concentration after the filters. In addition, we measured free hemoglobin, plasma elastase (Merck, Darmstadt, Germany), and complement C5-9 (Quidel, San Diego, CA, U.S.A.) to assess the biocompatibility of the filters. The circulating fat particles were calculated with an automated hematology analyzer. The passage time for the blood was shortest for the Biofil filter (P = 0.02, analysis of variance). The total leukocyte counts (P = 0.04) and fat particles (P = 0.02) were higher after the LipiGuard filter. This filter also had a higher increase in free hemoglobin concentration (P = 0.03). We conclude that the leukocyte removal filters were superior to the fat removal filter both in leukocyte and fat removal.

Synthesis and performance of amphiphilic copolymers for blood cell separation

Three types of amphiphilic copolymers using n-butylmethacrylate (BMA) as a hydrophobic monomer, and each of N,N'-dimethylacrylamide (DMA), N-acryloylmorpholine (AMO), and N-vinylpyrrolidone (VP) as hydrophilic comonomers were synthesized for coating filters used to remove leukocytes. The influence of the amphiphilic property of the resulting filters, which were composed of nonwoven fabrics coated with the above copolymers, on leukocyte removal and platelet permeation through the filters from whole blood was investigated. The platelet permeation ratio through hydrophobic noncoated filters was only 0.2%, because platelets in whole blood adhered easily to the hydrophobic filter material. However, filters coated with poly(AMO-co-BMA) of high AMO content showed a much higher platelet permeation ratio (nearly 90%). Further, the filters coated with poly(DMA-co-BMA) also showed high permeation ratios of platelets (more than 78%) over a broad range of DMA content in the copolymer. On the other hand, the coated filters showed slightly a higher permeation ratio of leukocytes than did the noncoated filters, resulting from the increase in hydrophilicity of the surface of the filters. Moreover, the coating of the amphiphilic copolymers on the surface of the nonwoven fabrics may have affected the pore size of the filters, affecting the permeation ratio of leukocytes more strongly than that of platelets. The coated filters effectively improved platelet permeation through the filters, with a slight increase in the permeation ratio of leukocytes.

Platelet storage lesion: The limited impacts of leukoreduction processes in retention of microvesicules, prion, and platelet-derived biological response modifiers

Currently, platelet concentrates are produced either from pooled buffy coats which are leukoreduced during processing by WBC removal filters, or several apheresis technologies with or without filtration. The effect of exposure to artificial surfaces during apheresis leukoreduction processes and the exposure to the blood collection set, filters and storage bags, on the generation/retention of microvesicles, prion protein and major biological response modifiers is largely unknown. Exposure to the matrix of charged platelet filters can lead to activation of complement, kallikrein/kinin and inflammatory systems as well as platelet activation, secretion and microvesiculation. It is therefore important to define the impact of various leukocyte removal processes on the extent of the platelet storage lesion and cellular apoptosis/necrosis.

Developments in the apheresis procedure for the treatment of inflammatory bowel disease

Initially used to treat rheumatoid arthritis, nonselective therapeutic leukocytapheresis was applied to the treatment of inflammatory bowel disease (IBD) as early as the 1980s. Since then, the process has been further refined and 2 blood perfusion systems using membrane filtration are presently employed in Japan and Europe for the selective removal of leukocytes in patients with IBD: Cellsorba is a column of polyethylenephtarate fibers that captures lymphocytes and granulocytes, and Adacolumn is a column of cellulose acetate beads that selectively adsorb granulocytes and monocytes. These systems overcome the limitations of centrifugation. Leukocytapheresis has been shown to exert an overall anti-inflammatory effect, as peripheral leukocytes demonstrated a diminished capacity to produce inflammatory cytokines such as tumor necrosis factor-alpha, interleukin (IL)-1, IL-6, IL-8, and IL-1beta. In addition, down-regulation in the expression of adhesion molecule L-selectin and a shift toward a more immature granulocyte phenotype were observed in the peripheral blood. The safety and beneficial therapeutic effect of leukocytapheresis in IBD are being investigated further.

Leukocyte removal efficiency of cell-washed and unwashed whole blood: an in vitro study

Leukocyte filtration of the cardiopulmonary bypass (CPB) perfusate after cardiac surgery has evolved as an important technique to prevent effector functions mediated by activated leukocytes. However, little is known about the filtration efficiency. Therefore, an in vitro study was conducted to define the leukocyte removal rate of a transfusion leukocyte-depletion filter, using cell-washed and unwashed whole porcine blood. In addition, the influence of different cell-washing protocols on the elimination rate of blood cells (leukocytes and platelets) was investigated. Fresh, diluted, pooled, heparinized, porcine blood was processed using either a high-flow (HF, n = 5) or quality-wash (QW, n = 5) protocol on a continuous auto-transfusion system, or was left unprocessed (control n=5). Thereafter, all samples were filtered using a transfusion leukocyte-depletion filter. Blood samples for measurement of hematocrit, white blood cell count, including leukocyte differentiation and platelet count, were taken before and after filtration. To compare the experimental groups, the removal rate was presented as the fraction of leukocytes or platelets removed per plasma volume. Cell washing significantly altered the fraction of leukocytes removed per plasma volume when compared to unprocessed blood (2.07 and 2.36 in the HF and QW groups, respectively, versus 1.34 in the control group, p = 0.008 for both). No statistically significant difference in leukocyte removal rate was observed between the different cell-washing protocols. The leukocyte differential count showed that, during all experiments, the neutrophils were removed most efficiently (99.7%). Overall, significantly more platelets were depleted after cell washing compared to the control group (1.47 and 1.60 in the HF and QW groups, respectively, versus 1.12 in the control group, p =0.008 and 0.032, respectively). Furthermore, the amount of blood that could be filtered using a single pass technique did not significantly differ between the experimental groups. However, a larger variation in the total amount of filtered blood was observed in the unprocessed group (570+/-398 mL) compared to the cell-washed groups (360+/-42 and 430+/-97 mL in the HF and QW groups, respectively). In conclusion, blood processing with an auto-transfusion system significantly enhances the leukocyte and platelet removal efficiency of the transfusion leukocyte-depletion filter that was studied. In particular, neutrophils were efficiently removed.

Treatment With Cytapheresis for Antineutrophil Cytoplasmic Antibody‐associated Renal Vasculitis and Its Effect on Anti‐inflammatory Factors

To evaluate the efficacy of cytapheresis for the treatment of rapidly progressive glomerulonephritis (RPGN) caused by myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA)-associated vasculitis, the renal prognosis and the mortality rate at 1 year after treatment were compared between a Cytapheresis Group and a Steroid Pulse Group. The Cytapheresis Group included 10 patients who were treated with cytapheresis and oral corticosteroids. Five had granulocytapheresis with the Adacolumn (Japan Immuno Research Laboratories Co. Ltd, Takasaki, Japan) and the remaining five had leukocytapheresis with the leukocyte removal filter, Cellsorba (Asahi Medical Co. Ltd, Tokyo, Japan). The Steroid Pulse Group was comprised of 12 patients who were treated with methylprednisolone pulse therapy and oral corticosteroids. In the Cytapheresis Group, renal function recovered in 70% of the patients and the mortality rate was 10%. In the Steroid Pulse Group, renal function recovered in 66.7% and the mortality rate was 33.3%, with infection as the cause of death. Total doses of corticosteroids converted to prednisolone dose during a 1 month period, ranged from 280 mg to 1226 mg in the Cytapheresis Group. On the other hand, these dosages ranged from 2375 mg to 8380 mg in the Steroid Pulse Group. These results indicated that the mortality rate by infection could be reduced by adding cytapheresis therapy. Concerning the mechanism of cytapheresis, anti-inflammatory factors such as soluble tumor necrosis factor receptor, and interleukin-10 reduced after cytapheresis. These changes might be responsible for the efficacy of cytapheresis. In conclusion, cytapheresis is thought to be one of the effective treatments for RPGN caused by MPO-ANCA-associated vasculitis, reducing the levels of anti-inflammatory factors.