Leukocyte Depletion Filters Research Articles

Strategies of myocardial protection for operation in chronic model of cyanotic heart disease

Background. Cyanotic congenital hearts have an increased susceptibility to ischemia and subsequent reperfusion. The role of platelet-activating factor antagonism and mechanical neutrophil depletion with leukocyte-depleting filters for control of ischemia-reperfusion injury was assessed in corrective surgical procedures for cyanotic heart disease. Methods. A swine model of cyanotic heart disease was evaluated with three study groups: a control group; a group given a platelet-activating factor antagonist (PAFA group); and a group with leukocyte-depleting filtration (LDF group). The cyanotic model was created with a left atrial appendage–pulmonary artery fistula with peripheral banding through a left anterior thoracotomy in weanling swine. The experimental procedure was performed 5 to 7 weeks later when body weight was greater than 20 kg and oxygen saturation was 85% or less. The corrective procedure was performed through a median sternotomy on cardiopulmonary bypass with repair of the shunt. Myocardial protection was accomplished with hypothermic blood-crystalloid (4:1) cardioplegia; the period of ischemic arrest was 90 minutes. In the PAFA group, the platelet-activating factor antagonist CV-6209 was delivered intravenously 15 to 20 minutes before aortic cross-clamping. In the LDF group, Pall leukocyte-depleting filters were used in the CPB arterial line. Hemodynamic data were taken before operation and 10 and 30 minutes after CPB with impedance ventriculography. Results. There were four deaths in the control group within 30 minutes after CPB; all animals in the treated groups survived longer than 60 minutes ( p < 0.05). The ventricular assessment of end-systolic elastance revealed superior performance in the LDF group 30 minutes after CPB compared with the control group ( p < 0.05) (controls, 4.0 ± 9; PAFA group, 6.5 ± 3.7; and LDF group, 12.0 ± 4.6). Conclusions. Both leukocyte-depleting filters and platelet-activating factor antagonism provided myocardial protection, and the filters afforded superior postoperative myocardial contractility.

Kinetics of Bradykinin Levels during and after Leucocyte Filtration of Platelet Concentrates

Abstract Objective: To measure beadykinin levels in platelet concentrates during and after leucocyte filtration. Methods: Platelet concentrates were leukocyte depleted using three different leucocyte‐depletion filters selected to represent filters with negative, positive or neutral charge, respectively. Bradykinin levels were analysed before, during and up to 90 min post‐filtration. Results: Significant levels of bradykinin were generated when negatively charged leucocyte depletion filters were used. However, we found a high variation between platelet concentrates prepared from different donors as well as within the same concentrate when this was divided into three aliquots. Generated bradykinin was rapidly degraded in the collection bag and no bradykinin was detectable 60 min post‐filtration. Conclusion: Bradykinin generation is more pronounced when negatively charged leucocyte removal filters are used. Due to a rapid degradation of bradykinin in the storage bag, pre‐storage filtration should minimise the risk of bradykinin related adverse reactions during transfusion with some filters.

Kinetics of Bradykinin Levels during and after Leucocyte Filtration of Platelet Concentrates

Objective: To measure beadykinin levels in platelet concentrates during and after leucocyte filtration. Methods: Platelet concentrates were leukocyte depleted using three different leucocyte-depletion filters selected to represent filters with negative, positive or neutral charge, respectively. Bradykinin levels were analysed before, during and up to 90 min post-filtration. Results: Significant levels of bradykinin were generated when negatively charged leucocyte depletion filters were used. However, we found a high variation between platelet concentrates prepared from different donors as well as within the same concentrate when this was divided into three aliquots. Generated bradykinin was rapidly degraded in the collection bag and no bradykinin was detectable 60 min post-filtration. Conclusion: Bradykinin generation is more pronounced when negatively charged leucocyte removal filters are used. Due to a rapid degradation of bradykinin in the storage bag, pre-storage filtration should minimise the risk of bradykinin related adverse reactions during transfusion with some filters.

THE USE OF INTRAOPERATIVE CELL SALVAGE DURING PROCEDURES FOR SPINE MALIGNANCIES

S178 INTRODUCTION: The cumulative immunosuppressive effects of allogeneic transfusions have been well documented, thus the limitation of their use in patients with malignancies has been advocated. [1,2] The utilization of intraoperative cell salvage (ICS) during surgical procedures in patients with malignancies is controversial, as the potential for reintroduction of tumor cells into the patient exists. [3] We report our seven-year experience with using ICS to decrease patient exposure to allogeneic blood during gross-total resection and reconstruction procedures for primary and metastatic spinal tumors. METHODS: A retrospective review of the anesthesiologists' and surgeon's records of all patients underwent gross-total resection and reconstruction procedures for primary and metastatic spine tumors at a 1,200 bed tertiary care university medical center, between 1990 and 1996, was undertaken. Primary tumor sites and surgical procedures were noted. Intraoperative estimated blood loss (EBL), ICS data, allogeneic transfusion requirements and complications were recorded. Information regarding patient survival at <or=to1 year, <or=to2 years and > 2 years was sought. Data are presented as means +/- standard deviations. RESULTS: 98 patients underwent spinal surgery in which blood collected by the Haemonetics Cell Saver 4[registered sign] (Haemonetics Corp, Braintree, MA) was of sufficient quantity to be returned to the patient. A 20 micron filter (Baxter Healthcare, Roundlake, IL) was used during reinfusion of the ICS blood. Fourteen patients, who underwent 15 procedures, had primary tumors including chordoma (8), hemangioma (2), neurofibroma (2), and osteogenic sarcoma of the spine (2), while the major primary sites of metastatic tumors in 83 patients included: renal (15), hematologic (10), colorectal (7), breast (6) and gynecologic (6). Tumor resection, with or without spine instrumentation, occurred in the cervical spine (7), thoracic spine (52), lumbar spine (29) and sacrum (15). EBL for the procedures was 3004cc +/- 2629cc (range 400-16,000cc). Total ICS volume for all cases was 91,340cc, which equals 365.4 units of PRBCs reclaimed. Mean ICS volume of PRBCs was 932cc +/- 798cc (range 250-3,250cc) per case, while allogeneic RBC use was 4 units +/- 4.6 units (range 0-26 units). Of the patients with primary tumors 78.6% have >2 year survival, one succumbed to an intraoperative MI, another to postoperative complications from diabetes and sepsis, and one had <or=to2 year survival secondary to complications from his primary tumor. The majority of patients with metastatic disease underwent procedures because they had cord compression or spine instability, and hoped to achieve improved ambulation status and decreased pain. 25.3% of these patients have >2 year survival, 28.9% between 1 and 2 year survival and 43.4%<or=to1 year survival. DISCUSSION: The use of ICS for malignancies continues to be controversial. We employ a standard 20 micron filter during reinfusion rather than a 40 micron leukocyte depletion filter (LDF) during these procedures, because the severe limitation in reinfusion rate imposed by the LDF would negate the advantage of using ICS, rather than allogeneic blood, during periods of intraoperative hemorrhage. Our data reveal that the use of ICS during surgical procedures for patients with spinal malignancies has not affected long-term survival, while it has decreased their exposure to allogeneic blood. Malignancy should not be an absolute contraindication to the use of ICS; decisions regarding its use should be made after a careful consideration of the risks and benefits.

EVALUATION OF BLOOD TRANSFUSION AND CELLULAR IMMUNOLOGICAL ACTIVITY IN SURGERY FOR GASTROINTESTINAL CANCER

A total of 110 patients who were operated on for gastrointesinal cancer were subjected to a study of elucidating the correlations between intraoperative blood transfusion and postoperative cellular immunological activity. All patients were classified into three groups; homologous transfusion group, autologous transfusion group, and no transfusion group by intraoperative transfusion method. The ratio of CD4 to CD8 (CD4/CD8), natural killer cell activity (NK cell) and immunosuppressive acidic protein (IAP) were compared among these three groups before and after the operation. The NK cell activity decreased after the operation and the decrease was prolonged in the homologous transfusion group with or without leukocyte depletion filter. IAP increased postoperatively in the hemologous group without the filter, which was significantly higher than those of homologous group with the filter and autologous transfusion group. Postoperative infections occurred in 36% of the homologous, 16% of autologous transfusion group, and 2% of no-transfusion group. A significantly higher incidence of postoperative infections complication was noted in homologous group than that of autologous group. Compared with homologous transfusion, autologous transfusion is thought to be very useful in surgeries for gastrointestinal cancers in terms of the maintenance of the cellular immunological activity.

Removal of malignant cells through a leukocyte-depletion filter for autologous blood transfusion

Background It is now possible for leukocyte-depletion filters to be used for removing malignant cells from blood during autotransfusion in patients with malignant tumors. With the objective of ascertaining its clinical application in gynecologic surgery for malignant tumors, we have performed a basic investigation of the malignant cell depletion performance of the BPF4-BJ, a new, fourth-generation leukocyte-depletion filter.

Pulmonary Histopathology after Cardiopulmonary Bypass with Pall LG6 Leukocyte-Depleting Filter

There is increasing interest in the use of leukocyte-depleting filters to reduce the harmful effects of neutrophils during cardiopulmonary bypass. Pulmonary histopathology was studied in 7 patients before and after cardiopulmonary bypass. The arterial line leukocyte-depleting filter (Pall LG6) was used in 5 cases and the conventional arterial line filter (Pall Autovent) was used in 2 patients. The results showed no significant influence of the leukodepletion filter on pulmonary histopathologic changes associated with cardiopulmonary bypass.

5c Autologous haemotherapy in malignant diseases

Pre-donation of blood in cancer patients is effective and recommendable, but is limited by tumour anaemia, urgent scheduling of surgery and variable blood loss resulting in discarded autologous blood or homologous transfusions. Intra-operative autotransfusion is considered to be contraindicated in cancer surgery. This was confirmed by the recent demonstration of the frequent existence of vital, proliferating, invasive and tumorigenic tumour cells in high numbers in the blood shed during surgery of various cancers. Leukocyte depletion filters are unable to guarantee complete elimination of contaminating tumour cells because of the limited reduction rates. The radiosensitivity of the nucleated tumour cells, in contrast to the radioresistance of the unnucleated red blood cells, can be used for efficient elimination. For 50 Gy a 12 decade reduction can be calculated from radiosensitivity data, and experimentally a 10 decade reduction has been demonstrated, sufficient to eliminate any supposed tumour cell contamination. This combination of two well-established methods, intra-operative blood salvage and blood irradiation, in clinical practice proved to be an effective, practical and safe procedure for using autologous blood in cancer patients.

Effects on Complement, Granulocytes and Platelets of a Leukocyte-Depletion Filter During in vitro Extracorporeal Circulation

In an in vitro study, extracorporeal circuits equipped with either a leukocyte-depleting filter (n = 5) or a standard arterial-line filter (n = 5) were perfused for 120 minutes with fresh human whole blood. Leukocyte activation, leukocyte and platelet counts and complement activation were studied. Significant reduction of leukocyte and platelet counts and significant activation of leukocytes and of platelets were found in both groups, but without significant intergroup difference for any parameter after 120 minutes of perfusion. The leukocyte-depleting filters, however, were somewhat more effective in removing leukocytes during the initial 30 minutes of circulation.

Leucocyte depletion filter removes cancer cells in human blood: Kongsgaard UE, Wang MY, Kvalheim G. Acta Anaesthesiol Scandinavica 40:118–120, 1996

Leucocyte depletion filter removes cancer cells in human blood: Kongsgaard UE, Wang MY, Kvalheim G. Acta Anaesthesiol Scandinavica 40:118–120, 1996

Is the elimination of osteosarcoma cells with intraoperative "mesh autotransfusion" and leukocyte depletion filters possible?

Intraoperative autotransfusion is contraindicated in cancer surgery because of the possible risk of systemic tumor spread. The aim of the present study was to investigate whether a cell saver in combination with a white blood cell depletion filter can remove osteosarcoma cells. A defined number of osteosarcoma cells from an established cell line were added to red cell concentrates and Ringer solution. The tumor cell concentration was 1000/ ml in the first five experiments, 7111/ml in test no. 6, 1667/ml in test no. 7 and 167/ml in test no. 8. Following thorough mixing, each unit was processed separately by a cell saver (DIDECO BT 795/P) in its normal operation mode to produce a red cell concentrate. This red cell concentrate was filtered using a leukocyte depletion filter (PALL BPF 4). Samples were taken before and after processing with the autotransfuser and after filtration with the white cell depletion filter. Cytospin specimens from all samples were examined for osteosarcoma cells by three different methods (Papanicolaou stain, Vimentin antibodies, DNA analysis). After processing with the autotransfuser, tumor cells were identified in the red cell concentrate. No osteosarcoma cells were evident after the combined use of cell saver and leukocyte depletion filter. The sole use of the autotransfuser DIDECO BT 795/P during osteosarcoma surgery is not recommended because of the potential danger of retransfusion of malignant cells. In combination with the leukocyte depletion filter PALL BPF 4, no osteosarcoma cells were identified in the red cell concentrate. Since the adhesiveness of tumor cells from established cell lines may be different from that of tumor cells in the intraoperative salvaged blood, further studies with blood from the surgical field are necessary to determine the efficacy of white cell depletion filters to eliminate osteosarcoma cells.

The potential for reintroduction of tumor cells during intraoperative blood salvage: Reduction of risk with use of the RC-400 leukocyte depletion filter

Objectives Intraoperative autotransfusion of shed blood is widely utilized in surgery. However, several studies have raised concern about the transmission of tumor cells during oncologic procedures. We compared the ability of a leukocyte depletion filter (RC-400; LDF) to a standard red blood cell filter (SBF) to remove tumor cells derived from urologic malignancies. Methods Cells were suspended in media and passed through a SBF or a LDF. The filtrate was evaluated for the presence of viable cells utilizing the trypan blue exclusion method as well as cell culture. In a second experiment, cells were suspended in fresh bovine blood and processed through a cell saver apparatus followed by filtration with either a SBF or a LDF. Aliquots were cultured after admixture with blood, after processing, and after filtration. Results The LDF was able to remove tumor cells completely, as demonstrated by both counting with the trypan blue exclusion test and by cell culture. In contrast, admixture with blood, processing through the cell saver apparatus nor a standard red blood cell filter removed these cells. Conclusions Tumor cells derived from urologic malignancies are easily removed with a LDF but not with a SBF. Filtration of blood salvaged at the time of uro-oncologic surgery with a LDF but not with a SBF reduces the potential for reinfusion of viable tumor cells, urology ® 47: 179-181, 1996.

Leucocyte depletion filter removes cancer cells in human blood.

Autologous blood transfusion has been avoided in cancer surgery because of the metastatic potential of reinfused tumour cells. This study evaluated the efficacy of a blood transfusion filter in removing tumour cells from blood. Whole human blood was admixed with two different malignant cell lines (breast cancer PM1 and MCF7). The blood was filtered through a RC400TE leucocyte depletion filter. Unfiltered blood was used as a control. Detection of malignant cells was performed with immunomagnetic beads and clonogenic assays. No viable tumour cells were found after filtration with the leucocyte depletion filter. These findings suggest that the use of a leucocyte filter after intra-operative blood salvage may make autotransfusion safe even in tumour surgery.

Role of leukocyte depletion during cardiopulmonary bypass and cardioplegic arrest

Leukocyte depletion (LD) has been shown to be beneficial during the reperfusion of acutely ischemic myocardium; however, its role during cardiopulmonary bypass (CPB) in hearts protected with blood cardioplegia (BCP) is unknown. This experimental study sought to determine whether LD filters inserted in the CPB circuit before cardioplegic arrest and in the BCP circuit during arrest would decrease ischemic myocardial damage. In 20 pigs, the second and third diagonal vessels were occluded for 90 minutes, followed by 45 minutes of BCP arrest and 180 minutes of reperfusion on CPB. In 5 pigs, LD filters were inserted in both the CPB and BCP circuits (LD-CPB+BCP). Five pigs had LD during BCP (LD-BCP), 5 pigs had LD during CPB (LD-CPB), and 5 pigs had no LD. Ischemic damage was assessed by wall motion scores using two-dimensional echocardiography and the area of necrosis/area of risk. The LD-CPB and LD-CPB+BCP groups had the highest wall motion scores and the lowest area of necrosis/area of risk. The addition of LD to BCP alone did not significantly alter wall motion scores or the area of necrosis/area of risk. Leukocyte depletion filters significantly reduce ischemic damage during acute surgical revascularization and appear to be most effective when placed in the CPB circuit before cardioplegic arrest.

Cardiopulmonary bypass for adult patients: A survey of equipment and techniques

The techniques and equipment used for cardiopulmonary bypass for adult cardiac surgery vary among institutions and may change over time. This study sought to document the changing patterns of practice. Voluntary survey of meeting participants. 13th Annual San Diego Cardiothoracic Surgery Symposium (February 1993). There were 331 responses from perfusionists (79.5%), cardiac surgeons (11.2%), and anesthesiologists (6.3%). The majority of these participants were from institutions where more than 1,000 cardiac operations were performed annually. It was found that 91.5% of the respondents used membrane oxygenators currently, compared with 5% in 1982 (as reported in a previous survey). Over 80% of the institutions surveyed used some type of perioperative cell-salvaging technique. Arterial line filters were used by 92% of the respondents compared with 64% in 1982. Also, 80% of the respondents were aware of the availability of leukocyte-depleting filters. The probable reasons for the increased utilization of membrane oxygenators and arterial line filters include less damage to the formed elements of blood, fewer gaseous microemboli, and better control of carbon dioxide elimination and oxygenation. The authors anticipate that future surveys will document increased use of leukocyte-depleting filters because of the literature implicating neutrophils as mediators of tissue destruction in various disease processes, including myocardial reperfusion injury.

952-24 Role of Leukocyte Depletion During Cardioplegic Arrest

Leukocyte depletion (LD) filters may be beneficial during reperfusion of acutely ischemic myocardium; however, its role during cardiopulmonary bypass (CPB) and blood cardioplegic (BCP) arrest is unknown. This study sought to determine whether inserting LD filters during CPB and BCP arrest decreased ischemic damage. In 20 pigs, the 2nd and 3rd diagonal vessels were occluded for 90 minutes followed by 45 minutes of BCP arrest and 180 minutes of reperfusion on CPB. In 5 pigs, LD filters were inserted both in the CPB and BCP circuits (CPB + BCP), 5 pigs had LD during BCP only (BCP). 5 pigs had LD during CPB only (CPB). and 5 pigs had no LD. Ischemic damage was assessed by Wall Motion Scores IWMS) using 2-D echo (4 = normal to-1 = dyskinesia) and the Area of Necrosis/Area of Risk (AN/AR). Results are Mean ± SE. No LD BCP CPB CPB + BCP WMS 1.7 ± 0.4 2.0 ± 0.2 3.6 ± 0.1 * 3.4 ± 0.2 * AN/AR (%) 34 ± 2 29 ± 1 17 ± 1 * 19 ± 1 * * p &lt; 0.05 from no LD and BCP groups We conclude that LD filters significantly reduce ischemic damage and are most effective when placed in the CPB circuit.

Use of leukodepletion filters for the removal of bacteria.

Recipient exposure to allogeneic donor leukocytes can mediate a number of immunologic complications of transfusion or can transmit leukotropic viruses carried by the donor. Leukocyte depletion of cellular blood components has been shown to reduce the incidence of such complications. In recent years, prestorage leukocyte depletion by filtration has also been suggested as a means of decreasing the incidence of bacterial overgrowth in cellular blood components. This review analyzes published studies on the use of leukodepletion filters for removal of Staphylococcus epidermidis and Yersinia enterocolitica from blood. Although ineffective for removal of S. epidermidis from Platelet Concentrates, inoculation studies demonstrate removal of low levels of Y. enterocolitica from Red Cell Concentrates. Based on these studies, four possible mechanism(s) for removal of bacteria by leukodepletion filters are analyzed: phagocytosis by leukocytes during a prefiltration holding period; complement-mediated bacterial killing enhanced by filtration; adherence of bacteria to leukocyte surfaces retained within the filter; and direct removal of bacteria by the filter media. Just as multiple mechanisms appear to account for the efficiency with which these filters deplete blood of leukocytes, it is likely that more than one mechanism accounts for the experimental observation that leukocyte depletion filters can reduce overgrowth of Y. enterocolitica in stored Red Cell Concentrates.

Feasibility and rate of leucocyte depletion with a single leucocyte depletion filter during massive transfusion.

The study examines the feasibility and rate of leucocyte depletion with a single leucocyte depletion filter in combination with the Level 1 heat exchanging infusion/transfusion device H-500/H-25i during massive transfusions. LeukoGuard-6 filters (LG-6) were manufactured to fit the infusion sets of the Level 1 H-500/H-25i. This modified device was used intraoperatively in six patients with severe haemorrhage. Following determination of the white cell counts (WCC) in each buffy coat poor red cell concentrate prior to administration, WCC were then obtained from blood sampled directly distal to the filter after the first and after the last red cell concentrate was given. Leucocytes were determined in the Nageotte chamber and then calculated to determine leucocytes/250 ml (therapeutic unit). Parameters of feasibility (time for preparation of the system, the amount of transfused red cell concentrates, time interval of transfusions) were recorded. The mean volume of red cell concentrates which were transfused and filtered by a single filter was 2,708 ml (S.D. +/- 797 ml) within a mean time interval of 42.5 min (S.D. +/- 26 min). With a mean WCC of 1.17 +/- 0.68 x 10(9) leucocytes/250 ml in the red cell concentrate prior to filtration the LG-6 achieved a log-3 reduction of leucocyte counts. During the transfusion the WCC distal to the filter increased on average by a factor of 3 (from 0.9 x 10(6) leucocytes/250 ml following the first blood unit to 2.7 x 10(6) leucocytes/250 ml following the last), but remained below 5 x 10(6). Modification of the Level 1 H-500/H-25i system by incorporating the LG-6 leucocyte depletion filter provides a significant reduction of the WCC in the transfused red cell concentrates during massive transfusion. The rate of leucocyte depletion by a single leucocyte depletion filter achieves low leucocyte counts which are documented to be of therapeutical value. As the significance of leucocyte-reduced blood products for patients with haemorrhagic shock following trauma or major surgery has still to be elucidated, the presented device may be useful in the performance of future studies related to this subject.

Biologic effects of leukocytes present in transfused cellular blood products

A considerable literature has accumulated over the past decade indicating that leukocytes present in allogeneic cellular blood components, intended for transfusion, are associated with adverse effects to the recipient. These include the development of febrile transfusion reactions, graft-versus-host disease, alloimmunization to leukocyte antigens, and the immunomodulatory effects that might influence the prognosis of patients with a malignancy. Moreover, it has become evident that such leukocytes may be the vector of infectious agents such as CMV, HTLV-I/II, and EBV as well as other viruses. An interesting development that has occurred coincidentally in transfusion medicine is that agencies responsible for the provision of blood products are being designated manufacturers of biologicals. The trend among manufacturers of biologicals is to try to produce pure products to provide for the specific therapeutic need of patients. Thus, with the realization that allogeneic leukocytes and their products may have adverse biologic activities, there is increasing pressure from various sources for the reduction of the leukocyte content in allogeneic blood components to minimize the occurrence of their adverse effects. Although the threshold leukocyte number below which these effects might no longer occur is still to be determined, a 2 to 3 log10 leukocyte reduction, provided by the currently available commercial leukocyte filters, has been shown to reduce the frequency of many of such reactions. On the other hand, the immunosuppressive effects produced by the infusion of allogeneic leukocytes might be beneficial for some patients, ie, for the maintenance of kidney allografts, in possibly reducing the relapse rate in patients with inflammatory bowel diseases, and in ameliorating recurrent spontaneous abortion. Moreover, therapeutic granulocyte transfusions may be of benefit in certain well-defined categories of patients infected with bacteria, yeast, and/or fungi. These include neonates with bacterial sepsis associated with bone marrow failure as well as severely neutropenic leukemic patients with an infection unresponsive to appropriate and specific antibiotic therapy. Many of the results obtained with the use of leukocyte depletion filters are tantalizing, but the actual clinical benefit of leukodepletion has not been established in most instances, because much of the available data are retrospective or from uncontrolled clinical trials. Moreover, issues of cost-effectiveness and quality control have not been considered adequately. Properly designed prospective clinical trials are essential to provide data with which to answer such questions and also to help define the optimal conditions required for the preparation of blood components ultimately destined for clinical use. Only with the availability of such data can sound decisions be made about the clinical value of leukodepletion.

Effect of filtration on subsequently stored platelet concentrates.

The effect of filtration on the quality of platelet concentrates (PC) during storage was investigated. Two leukocyte depletion filters (Pall PL50HF and Sepacell PL-10A) were applied to filter PC made from a pool of 4 buffy coats. For each experiment 3 PC were pooled and divided into 3 identical PC to eliminate differences between the PC. Two PC were filtered, and the third PC served as an unfiltered control. A total of 12 experiments was performed. Before filtration, volumes of the PC were 263 +/- 11.7 ml (mean +/- SD). Platelet and leukocyte counts per PC were 241 +/- 25.9 x 10(9) and 7.2 +/- 1.8 x 10(6), respectively. After filtration leukocyte counts did not exceed 5 x 10(4) in any of the PC. In the PC filtered with the Pall PL50HF the mean platelet loss was approximately 14% and with the Sepacell PL-10A, 17%. During a 9-day storage period the pH, PO2, PCO2, bicarbonate, lactate and glucose concentration and LDH release as well as the morphology, examined by the swirling effect and microscopically, were not significantly different in filtered and unfiltered units. Filtration through the 2 investigated leukocyte depletion filters for PC did not adversely affect in vitro viability of the platelets during storage.