Leukocyte reduction of blood components: public policy and new technology

Donors with repeated blood product discards for filtration problems, clots or hemolysis: Causes and follow-up

INTRODUCTION

Sanquin donor medicine department is informed when donations or their components are rejected. This can occur isolated or frequently. It is undesirable because the donations cannot be used and there may be an underlying medical cause. Based on regional approaches, a uniform procedure was developed.

METHODS

Information about whole blood, plasma- plateletpheresis donations from which one or more components were rejected for filtration time (>2 h), hemolysis or clots were extracted from blood bank information system. After rejection of two successive components or donations or total ≥3 the donor is contacted. Depending on the medical history and investigation by the family doctor, the donor carrier is re-evaluated. We looked for the causes of the discarded products and performed a survey among blood services regarding polices with discarded products.

RESULTS

One or more components from 1742 of about 2.2 million successful donations (0.08%) were rejected. The highest percentage of rejection was seen in plateletpheresis (1.5%), all for clots. No underlying medical causes were found. 24 whole blood donors were found to have sickle cell trait (SCT) and were permanently deferred. The policies for follow-up after discarded products or acceptance of SCT donors vary between the 16 blood banks. Six organizations do not follow-up donors and seven accept SCT for blood or plasma donation.

CONCLUSION

Informing donors with repeated discarded products avoids the non-use of donations. Causes of repeated discarded products can be found by follow-up of donors. The results of the survey indicate a large discrepancy in policies applied worldwide.

A retrospective observational study to estimate the risk of HLA alloimmunization with blood transfusion: Can the risk be reduced by leucodepletion?

BACKGROUND

In this retrospective study, our aim was to find the effect of leucodepleted (LD) blood transfusions on the formation of anti-HLA-antibodies when compared to non-leucodepleted (non-LD) transfusions using Luminex-based method.

METHODS

In this study, Luminex single antigen bead assay (L-SAB) and HLA typing were performed on 310 patients. Test positivity rates (as MFI - Mean florescence intensity) were analyzed according to the different sensitization events and gender.

RESULTS

Of the 310 patients included in the study, 58.06% (180) patients were male and 41.93% (130) were female. The average age of the patients was 42.86 (±12.37) years. In this study, test positivity rates were significantly lower in the patients who received LD RBC units than in those who received non-LD RBC units (28.43% = 29 of 102 Vs 55.22% = 74 of 134, p < 0.05). In our study, transfusion combined with a history of pregnancy had higher number of significant HLA antibodies compared to cases where transfusion was the only sensitization event (81.81% = 18/22 Vs 39.71% = 85/214, p < 0.05). In addition, anti-HLA-antibodies-MFI were significantly (p < 0.01) higher in non-LD patients compared to LD patients.

CONCLUSION

Patients who received LD RBC units had a significantly lower rate of transfusion-associated alloimmunization compared to those who received non-LD RBC units. Multiparous women had a high risk for transfusion-related alloimmunization compared to both nulliparous women and male patient. Furthermore, class I-anti-HLA-antibodies (HLA-B and HLA-A + B) were significantly associated with pregnancy sensitization and/or blood transfusion as a single sensitization.

Transfusion trigger after operations in high cardiac risk patients (TOP) trial protocol. Protocol for a multicenter randomized controlled transfusion strategy trial

BACKGROUND

There is substantial uncertainty regarding the effects of restrictive postoperative transfusion among patients who have underlying cardiovascular disease. The TOP Trial's objective is to compare adverse outcomes between liberal and restrictive transfusion strategies in patients undergoing vascular and general surgery operations, and with a high risk of postoperative cardiac events.

METHODS

A two-arm, single-blinded, randomized controlled superiority trial will be used across 15 Veterans Affairs hospitals with expected enrollment of 1520 participants. Postoperative transfusions in the liberal arm commence when Hb is <10 g/ dL and continue until Hb is greater than or equal to 10 g/dL. In the restrictive arm, transfusions begin when Hb is <7 g/dL and continue until Hb is greater than or equal to 7 g/dL. Study duration is estimated to be 5 years including a 3-month start-up period and 4 years of recruitment. Each randomized participant will be followed for 90 days after randomization with a mortality assessment at 1 year.

RESULTS

The primary outcome is a composite endpoint of all-cause mortality, myocardial infarction (MI), coronary revascularization, acute renal failure, or stroke occurring up to 90-days after randomization. Events rates will be compared between restrictive and liberal transfusion groups.

CONCLUSIONS

The TOP Trial is uniquely positioned to provide high quality evidence comparing transfusion strategies among patients with high cardiac risk. Results will clarify the effect of postoperative transfusion strategies on adverse outcomes and inform postoperative management algorithms.

TRIAL REGISTRATION

http://clinicaltrials.gov identifier: NCT03229941.

Changes in the incidence of transfusion reactions in hematological patients over the past 30 years

BACKGROUND

Patients with hematological diseases are polytransfused and often immunocompromised, therefore susceptible to transfusion reactions (TR). This study aims to document the incidence of TRs in adult hematological patients and assess the effect of changes in the production of blood components and transfusion practice on their occurrence.

STUDY DESIGN AND METHODS

Retrospective observational analysis of TRs reported from 1993 to 2019 was performed. For the analysis of the effect of changes on the incidence of TRs, the evaluated time was divided into two periods: the 1st period before the introduction of changes in production, when leukoreduced blood components were used only selectively, and the 2nd period, when semi-automated method of production and universal leukoreduction was introduced.

RESULTS

The decrease in the incidence of TRs was observed for both red blood cell (RBC) and platelet concentrate (PC) transfusions in the 2nd period. Since platelet additive solution has been used, a further decrease in the incidence was reported. The decrease in incidence was also observed for delayed hemolytic/serological transfusion reactions and for transfusion-transmitted bacterial infections. Four cases of incorrect blood transfusions were uniquely related to the hematological patients, caused by antigen loss and transfusion ordering after ABO-incompatible hematopoietic stem cell transplantation.

DISCUSSION

Our results provided evidence that the introduction of tools offered by modern transfusion medicine: universal leukodepletion, plasma replacement with additive solutions, sensitive laboratory techniques, prophylactic antigen matching policy, informatization, and automatization, decreased the incidence of TRs and improved transfusion safety.

Quality validation of platelets obtained from the Haemonetics and Trima Accel automated blood-collection systems

BACKGROUND

Platelet transfusion is required to treat haemo-oncology or trauma patients. Platelet apheresis (PA) performed with apheresis equipment has increased rapidly in recent years. Leucocyte-reduced platelet apheresis (LRPA) can reduce the risk of platelet refractoriness and febrile nonhemolytic transfusion reactions (FNHTRs) for transfusion. Accordingly, this study aimed to investigate and compare the platelet metabolic and functional responses between PA performed with Haemonetics and LRPA performed with Trima Accel cell separator.

METHODS

The qualities of platelets collected through PA and LRPA were evaluated in terms of visual appearance, morphology, platelet-aggregation changes, metabolic activities, and bacterium-screening test during 5-day storage. Statistical analyses included two-sample t-test and generalised estimating equation(GEE) method.

RESULTS

During 5-day storage in LRPA, residual leucocytes were all <1.0×10⁶, and the parameters of platelet function were as follows: platelet aggregated to agonists such as adenosine 5'-diphosphate (ADP) and collagen, and the extent of shape change and pO₂ showed no statistically significant difference between PA and LRPA. The hypotonic shock reaction (HSR) on days 0, 1, and 3 were significantly higher in LRPA than in PA (71.78±6.92 vs. 64.10±7.42; P=0.002; 71.53±8.98 vs. 62.96±9.84; P=0.007; 68.05±7.28 vs. 57.76±6.80; P<0.0001, respectively). Values of mean platelet volume (MPV) were statistically larger in PA than in LRPA on days 0, 1, and 3. On day 5, the swirling score was higher in LRPA than in PA. The mean lactate levels had no statistically significant difference between PA and LRPA. Moreover, no growth was observed through bacterium-screening test conducted on 40 samples.

CONCLUSION

Comparison of LRPA and PA products collected from the Trima Accel and Haemonetics automated blood-collection systems, respectively, revealed that both products possessed good platelet qualities even though additional processes are needed to reduce leucocytes. Furthermore, investigating the outcomes of other apheresis instruments with focus on the safety of donors, products, and recipients is necessary.

Improving blood transfusion safety in resource-poor countries: a case study of using leucocyte reduced blood in Uganda

Background:

The majority of blood transfusion safety strategies recommended by the WHO for resource-poor countries focus mainly on reducing the risk of transfusion-transmitted infections (TTIs). Other technologies such as leucocyte reduction may represent complementary strategies for improving transfusion safety.

Objective:

To evaluate the role of using leucocyte reduced blood in a resource-poor country.

Methods:

Pre-storage leucocyte reduced (LR) red blood cells (RBCs) were specially prepared for the Tissue Oxygenation by Transfusion in severe Anaemia and Lactic acidosis (TOTAL) study, at the Uganda Blood Transfusion Services from February 2013 through May 2015. Quality control tests were performed to evaluate the procedure, and the incremental cost of an LR-RBC unit was estimated.

Results:

A total of 608 RBCs units were leucocyte reduced. Quality control tests were performed on 55 random RBCs units. The median (IQR) residual leucocyte count was 4 (0·5–10) WBC/uL, equivalent to 1·8x106 WBC per unit. The estimated incremental unit cost of leucocyte reduction was $37 USD per LR RBC unit.

Conclusion:

Leucocyte reduction of blood in a resource-poor country is doable although relatively costly. As such, its value in resource-poor countries should be weighed against other transfusion safety propositions.

Non-electrical powered continuous cell concentration for enumeration of residual white blood cells in WBC-depleted blood using a viscoelastic fluid

White blood cells (WBCs) are one of the critical components whose number has to be reduced before blood transfusion, failing which adverse transfusion effects may occur in patients. However, due to the extremely low concentration of residual WBCs (r-WBCs) in WBC-depleted blood, it is difficult to quantify r-WBCs accurately without using expensive and voluminous instruments. Therefore, the development of a continuous cell concentration technique is required to produce a countable number of cells from rare cells, which cannot normally be detected. In this paper, we present a viscoelastic microfluidic device for sheathless, continuous concentration of WBCs. The device performance was evaluated using polystyrene particles with different sizes at various flow rate conditions in a non-Newtonian fluid compared to a Newtonian fluid. Large particles with a blockage ratio higher than 0.1 were tightly focused at the center and collected at the center outlet with a 98% collection ratio. Meanwhile, the viscosity effect of lysed blood samples with various hematocrits was considered. Finally, diluted WBCs with various dilution ratios were concentrated by ~18-fold and continuous concentration of WBCs in lysed blood samples was performed using a non-electrical powered hand pump sprayer. Without using an external power source, center-focused WBCs were collected at the center outlet at approximately 150 μl/min and the final number of WBCs was increased to 1.8 × 10⁴ cells/ml from undetectable levels.

Immunomodulatory Effects of Blood Transfusion on Tumor Size, Metastasis, and Survival in Experimental Fibrosarcoma

In spite of efforts, blood transfusion is still accompanied with adverse effects such as transfusion-related immunomodulation (TRIM). The current study aimed to evaluate the effects of allogeneic, syngeneic, fresh and storage blood transfusion on the growth and metastasis of tumors and survival in fibrosarcoma bearing BALB/c mice. Twenty-five BALB/c mice were grouped into five groups of equal size. All groups were injected 1.2 × 10⁶ WEHI-164 cells subcutaneously to induce fibrosarcoma tumor. After expansion of the tumor, in four groups (except for the control group), hemorrhage-induced anemia was developed. Twenty-four hours later, blood deficit was replaced by fresh allogeneic, storage allogeneic, fresh syngeneic and storage syngeneic blood transfusion, respectively. After a blood transfusion, for 13 days, the tumor size and survival of the mice were evaluated. In the day 20, the mice were sacrificed and their spleen tissues were evaluated for TRIM induced metastasis. Tumor size increase in the groups that received allogeneic (fresh and storage) and storage syngeneic blood transfusion was significantly higher than the control group (P value < 0.05). However, no significant difference was present in survival between the experiment groups and the control group. There was no metastasis in none of groups at the end of the study. Allogeneic and storage blood transfusion could have immunomodulatory effects such as increased tumor size. However, it seems that fresh and syngeneic blood transfusion have no effects on tumor growth in fibrosarcoma bearing mice. Further evidence may prove that more attention is warranted in blood transfusion into cancer cases.

Thrombocytopenia and Critical Care Medicine

Platelet transfusions play an important role in the treatment of critically ill patients. Like any blood component, however, there are various aspects of platelet transfusion therapy that need be considered by the intensivist. These include the proper dose and type of platelet component to infuse, as well as the route and method of administration. Methods to reduce the volume of the transfused platelets, for example, must ensure that the infused platelets will be functional and viable, posttransfusion. Treatment and diagnosis of the HLA alloimmunized recipient can pose a serious challenge to the clinician and an obstacle to adequate platelet therapy. An ICU patient for whom an adequate posttransfusion platelet increment cannot be achieved is at great risk of suffering a fatal hemorrhage. The ICU physician should be aware of the techniques used in modern transfusion practice to avoid having to deal with this complication. Adverse reactions to platelet transfusion include not only serologic ones, but those related to febrile and allergic complications, as well as infectious complications. The latter group includes diseases caused by infection with cytomegalovirus, bacteria, and a cadre of viruses including HIV and hepatitis. The clinical approach to thrombocytopenia in the ICU will be covered in some detail in an effort to review many of the conditions associated with recipient thrombocytopenia, including ITP, TTP, dilutional thrombocytopenia, DIC, surgery, HELLP syndrome, and drug-induced thrombocytopenia. Unfortunately the treatment approaches traditionally used are not always derived from evidence-based studies. This review covers many of these topics in an attempt to help physicians become better able to manage thrombocytopenia in the ICU and thus provide the best transfusion therapy for their patients.

Role of Leukoreduction of Packed Red Blood Cell Units in Trauma Patients: A Review

Hemorrhagic shock is a leading cause of mortality within the trauma population, and blood transfusion is the standard of care. Leukoreduction filters remove donor leukocytes prior to transfusion of blood products. While the benefits of leukocyte depletion are well documented in scientific literature, these benefits do not translate directly to the clinical setting. This review summarizes current research regarding leukoreduction in the clinical arena, as well as studies performed exclusively in the trauma population.

A systematic review of transfusion-associated graft-versus-host disease

Transfusion-associated graft-versus-host disease (TA-GVHD) is a rare complication of blood transfusion. The clinicolaboratory features of TA-GVHD and the relative contributions of recipient and component factors remain poorly understood. We conducted a systematic review of TA-GVHD reports. The HLA relationship between donor and recipient was classified as D = 0 when no donor antigens were foreign to the recipient vs D ≥ 1 when ≥1 donor antigen disparity occurred. We identified 348 unique cases. Criteria for component irradiation were met in 48.9% of cases (34.5% immune-compromised, 14.4% related-donor), although nonirradiated components were transfused in the vast majority of these (97.6%). Components were typically whole blood and red cells. When reported, component storage duration was ≤10 days in 94%, and 23 (6.6%) were leukoreduced (10 bedside, 2 prestorage, and 11 unknown). Among 84 cases with HLA data available, the category of D = 0 was present in 60 patients (71%) at either HLA class I or II loci and was more common among recipients without traditional indications for component irradiation. These data challenge the historic emphasis on host immune defects in the pathogenesis of TA-GVHD. The dominant mechanism of TA-GVHD in both immunocompetent and compromised hosts is exposure to viable donor lymphocytes not recognized as foreign by, but able to respond against, the recipient.

Cost-effectiveness of leucoreduction for prevention of febrile non-haemolytic transfusion reactions

BACKGROUND

The cost-effectiveness of universal leucoreduction of blood components remains unclear. When using leucoreduced red blood cells, the decrease in the rate of febrile non-haemolytic transfusion reactions (FNHTR) is the only proven, meaningful clinical benefit, whose relationship to costs can be calculated relatively easily. The aim of this study was to evaluate the cost-effectiveness of leucoreduction in avoiding FNHTR.

MATERIALS AND METHODS

Data were obtained from two large tertiary hospitals in Athens, Greece, over a 4-year period (2009-2012). The incidence of FNHTR in patients transfused with leucoreduced or non-leucodepleted red blood cells, the additional cost of leucoreduction and the cost to treat the FNHTR were estimated. The incremental cost-effectiveness ratio (ICER), which is the ratio of the change in costs to the incremental benefits of leucoreduction, was calculated.

RESULTS

In total, 86,032 red blood cell units were transfused. Of these, 53,409 were leucodepleted and 32,623 were non-leucoreduced. Among patients transfused with leucodepleted units, 25 cases (0.047%) met the criteria for having a FNHTR, while in patients treated with non-leucoreduced components, 134 FNHTR were observed (0.411%). The ICER of leucoreduction was € 6,916 (i.e., the cost to prevent one case of FNHTR).

CONCLUSIONS

Leucoreduction does not have a favourable cost-effectiveness ratio in relation to the occurrence of FNHTR. However, many factors, which could not be easily and accurately assessed, influence the long-term costs of transfusion. It is imperative to undertake a series of large, meticulously designed clinical studies across the entire spectrum of blood transfusion settings, to investigate most of the parameters involved.

Cytokine concentration in stored canine erythrocyte concentrates

OBJECTIVE

To evaluate the effect of leukoreduction (LR) as compared to standard nonleukoreduced (NLR) units on cytokine concentrations in canine erythrocyte concentrates during regular storage time.

DESIGN

Randomized, experimental study.

SETTING

University teaching hospital.

ANIMALS

Ten random-source research dogs.

INTERVENTIONS

One unit of whole blood was collected from each dog and randomized to standard processing (NLR, n = 5) or prestorage LR (n = 5). All units were stored at 4°C. Samples were aseptically collected from each unit weekly for 5 weeks. On day 35, 1 mL of blood was collected from each unit and submitted for aerobic culture.

MEASUREMENT AND MAIN RESULTS

An ELISA assay was used to analyze the concentrations of IL-1β, IL-8, TNF-α, and IL-10. There were no significant effects of either group or storage time for IL-1β, IL-10, or TNF-α. IL-8 concentration was significantly increased over the storage period in NLR units, and was significantly higher compared to LR units on days 28 and 35. Aerobic culture was negative on all units.

CONCLUSIONS

This study demonstrated a marked, storage time-dependent accumulation of IL-8 in canine erythrocyte concentrates. Prestorage LR attenuated the accumulation of IL-8. This chemokine may contribute to the proinflammatory effects of transfusion of stored erythrocyte concentrates.

Red blood cell transfusions for thalassemia: results of a survey assessing current practice and proposal of evidence-based guidelines

BACKGROUND

In the absence of curative treatment, such as stem cell transplant, regular transfusions remain the mainstay of therapy for individuals with thalassemia major, a syndrome that results from marked ineffective erythropoiesis and the resultant anemia. The primary objectives of transfusion therapy are twofold: to suppress ineffective erythropoiesis and to ensure appropriate growth and development through childhood. In practice, a number of different transfusion protocols are in use across the developed world, with on-demand transfusion still being the paradigm in most of the developing world with limited resources.

STUDY DESIGN AND METHODS

To investigate perceived differences in transfusion practice, a self-reported electronic survey was disseminated to eight US thalassemia treatment centers in February 2011. The survey was divided into sections ranging from laboratory and clinical practices to emerging transfusion-transmitted diseases.

RESULTS

The survey response rate was 100%. The total number of transfused patients was 411. One-hundred percent of institutions used leukoreduced blood. No centers routinely provided cytomegalovirus-seronegative red blood cells (RBCs). Half the centers provided irradiated RBCs; only one routinely provided washed RBCs, and none transfused RBCs of defined storage age. Seventy-five percent of centers routinely phenotyped thalassemia patients' RBC antigens; 50% prophylactically matched for Rh and K antigens. The frequency of antibody investigations varied widely, and 25% of centers routinely medicated patients before transfusion.

CONCLUSION

Eight thalassemia centers in the United States were surveyed to determine the uniformity of transfusion practice. The variability of the results was surprising. Consequently, we performed a literature review and propose an evidence-based protocol for routine transfusion therapy for patients with thalassemia.

Real-time amplification of glyceraldehyde-3-phosphate dehydrogenase gene for quality control of leukopoor platelets

BACKGROUND

Leukoreduction of blood products is crucial to prevent white blood cell (WBC)-associated complications during transfusion. Of the widely accepted methods for quantifying WBCs in blood components, Nageotte hemocytometry is time-consuming and laborious whereas a specialized instrument is required for flow cytometry. A reliable and affordable method to assess WBC count in blood products is of particular interest.

STUDY DESIGN AND METHODS

Real-time polymerase chain reaction (PCR) of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene was developed for quantifying WBCs in leukopoor platelets (LPPs). After normalization by the cell-free prefiltrated and postfiltrated plasma DNA, the relative copy number of GAPDH gene in the platelet (PLT) concentrate and its corresponding LPPs was calculated according to the equation of 2(-ΔΔCt) of which Ct is defined as the threshold cycle. The percentage and the number of WBCs that remained in LPPs were consequently determined. This method was compared to Nageotte hemocytometry and was validated by using serially diluted PLT concentrate and 10 pairs of PLT concentrate-LPP samples.

RESULTS

Consistent with the removal of WBCs after filtration, the Ct values for the LPP samples were increased when compared to their corresponding PLT concentrate. As revealed by real-time PCR of GAPDH gene, there is a correlation between the calculated and theoretical WBC count in the serially diluted PLT concentrate (correlation coefficient, 0.9532). The WBC counts for the 10 LPP samples were comparable between Nageotte and real-time PCR method and were all below 3.3 × 10(6) WBCs/L.

CONCLUSION

The real-time PCR method we report in this study is applicable for routine quality assurance during leukoreduction process.

[Viral infection risk in polytransfused adults: seroprevalence of seven viruses in central Tunisia]

The aim of this study is to evaluate the prevalence of seven transfusion-transmitted viruses in polytransfused adults and children comparatively with a group of healthy control subjects. We studied 107 polytransfused patients (59 adults and 48 children) and 160 control subjects (100 blood donors and 60 children). Immunoenzymatic tests were used for detection of HBs antigen (HBs Ag), antibodies against hepatitis C Virus (anti-HCV), and human immunodeficiency virus (anti-HIV), and IgG antibodies against human cytomegalovirus (IgG anti-CMV), human parvovirus B19 (IgG anti-PB19), and hepatitis E virus (IgG anti-HEV). An immunofluorescent assay was performed for the detection of human herpesvirus 8 antibodies (anti-HHV8). Prevalence of HBs Ag, anti-HCV, anti-HIV, IgG anti-CMV, IgG anti-PB19, IgG anti-HEV, and anti-HHV8 in polytransfused group was 8.4, 4.7, 0, 86.9, 60.7, 28.9, and 47.6%, respectively, and 1.8, 0.6, 0, 86.2, 53.1, 10, and 12.5%, respectively, in the control group. The difference in prevalence between the two groups was statistically significant for HBs Ag (P = 0.01), anti-HCV (P = 0.03), IgG anti-HEV (P < 10(-4)), and IgG anti-HHV8 (P < 10(-4)). Categorization according to age showed that hepatitis B and C risk was limited in adult polytransfused group. HHV8 infection was higher in polytransfused subjects born before the use of leucocyte-depleted blood components. Our results corroborate literature data on the risk of HEV and HHV8 infection by blood transfusion. Hepatitis B vaccination and improvement in screening tests have an important role in reduction of hepatitis B and C risk in transfusion, especially in young polytransfused persons. However, a residual risk of transmitting viral infections persists, and efforts are needed to improve transfusion safety.

Establishment of a semi-automated pathogen DNA isolation from whole blood and comparison with commercially available kits

Molecular methods for bacterial pathogen identification are gaining increased importance in routine clinical diagnostic laboratories. Achieving reliable results using DNA based technologies is strongly dependent on pre-analytical processes including isolation of target cells and their DNA of high quality and purity. In this study a fast and semi-automated method was established for bacterial DNA isolation from whole blood samples and compared to different commercially available kits: Looxster, MolYsis kit, SeptiFast DNA isolation method and standard EasyMAG protocol. The newly established, semi-automated method utilises the EasyMAG device combined with pre-processing steps comprising human cell lysis, centrifugation and bacterial pellet resuspension. Quality of DNA was assessed by a universal PCR targeting the 16S rRNA gene and subsequent microarray hybridisation. The DNA extractions were amplified using two different PCR-mastermixes, to allow comparison of a commercial mastermix with a guaranteed bacterial DNA free PCR mastermix. The modified semi-automated EasyMAG protocol and the Looxster kit gave the most sensitive results. After hybridisation a detection limit of 10(1) to 10(2) bacterial cells per mL whole blood was achieved depending on the isolation method and microbial species lysed. Human DNA present in the isolated DNA suspension did not interfere with PCR and did not lead to non-specific hybridisation events.

Universal white blood cell reduction in Europe: has transmission of variant Creutzfeldt-Jakob disease been prevented?

Universal white blood cell (WBC) reduction was introduced in Europe to prevent transmission of variant Creutzfeldt-Jakob disease (vCJD) by transfusion. Findings from rodent models indicate that WBC reduction should not prevent vCJD transmission because the residual plasma infectivity suffices to infect transfusion recipients even under optimistic infectivity assumptions. Although infectivity in human blood may not partition in the manner in which it is distributed in rodents, prion-reduction filters remove the residual plasma infectivity in rodent models. Precautionary introduction of prion filtration in the UK--for patients without dietary exposure to bovine spongiform encephalopathy and in the absence of a reported case of vCJD transmission attributable to infectivity residing in plasma--is consistent with the (already in place for such subjects) precautionary importation to the UK of fresh frozen plasma from low-risk countries. Thus, implementation of prion filtration in the UK does not imply that universal WBC reduction--as currently practiced in Europe--does not abrogate transmission of vCJD. Because neither a human case of vCJD transmission through transfusion of WBC-reduced red blood cells nor a case of experimental bovine spongiform encephalopathy transmission by WBC-reduced transfusion to sheep has been reported, it cannot be concluded that ordinary WBC reduction is ineffective in preventing transfusion transmission in humans. Accordingly, universal WBC reduction for the prevention of vCJD in Europe should continue.

Transfusion thresholds and other strategies for guiding allogeneic red blood cell transfusion

BACKGROUND

Most clinical practice guidelines recommend restrictive red cell transfusion practices, with the goal of minimising exposure to allogeneic blood (from an unrelated donor). The purpose of this review is to compare clinical outcomes in patients randomised to restrictive versus liberal transfusion thresholds (triggers).

OBJECTIVES

To examine the evidence for the effect of transfusion thresholds on the use of allogeneic and/or autologous blood, and the evidence for any effect on clinical outcomes.

SEARCH STRATEGY

Trials were identified by: computer searches of the Cochrane Central Register of Controlled Trials (the Cochrane Library Issue 3, 2009), OVID MEDLINE (1966 to August 2009), Current Contents (1993 to November 2004), and the Web of Science (2004 to August 2009). References in identified trials and review articles were checked and experts contacted to identify any additional trials.

SELECTION CRITERIA

Controlled trials in which patients were randomised to an intervention group or to a control group. Trials were included where intervention groups were assigned on the basis of a clear transfusion 'trigger', described as a haemoglobin (Hb) or haematocrit (Hct) level below which an RBC transfusion was to be administered.

DATA COLLECTION AND ANALYSIS

Relative risks of requiring allogeneic blood transfusion, transfused blood volumes and other clinical outcomes were pooled across trials, using a random effects model. The risk of bias was assessed.

MAIN RESULTS

Seventeen trials involving a total of 3746 patients were identified. Restrictive transfusion strategies reduced the risk of receiving a red blood cell (RBC) transfusion by a relative 37% (RR=0.63; 95% CI 0.54 to 0.74). This equates to an average absolute risk reduction (ARR) of 33% (95% CI 21% to 45%). The volume of RBCs transfused was reduced on average by 0.75 units (95% CI 0.20 to 1.30 units). However, heterogeneity between trials was statistically significant (P<0.001; I²≥74%) for these outcomes. Restrictive transfusion strategies did not appear to impact on the rate of adverse events compared to liberal transfusion strategies (i.e. mortality, cardiac events, myocardial infarction, stroke, pneumonia and thromboembolism). Restrictive transfusion strategies were associated with a statistically significant reduction in the rates of infection (RR=0.76; 95% CI 0.60 to 0.97). The use of restrictive transfusion strategies did not reduce hospital or intensive care length of stay.

AUTHORS' CONCLUSIONS

The existing evidence supports the use of restrictive transfusion triggers in patients who are free of serious cardiac disease. The effects of conservative transfusion triggers on functional status, morbidity and mortality, particularly in patients with cardiac disease, need to be tested in further large clinical trials. In countries with inadequate screening of donor blood, the data may constitute a stronger basis for avoiding transfusion with allogeneic red cells.

Obtaining of CD34+ cells from healthy blood donors: development of a rapid and efficient procedure using leukoreduction filters

BACKGROUND

Human CD34+ cells are mandatory to study many aspects of human hematopoiesis. Their low frequency in blood or marrow and ethical reasons limit their obtainment in large quantities. Leukoreduction filters (LRFs) are discarded after preparation of red blood cells. The CD34+ cell concentration in healthy donor blood is low (1×10(3) -4×10(3) /mL), but their number trapped in one LRF after filtration of 400 to 450mL of blood is high (0.4×10(6) -1.6×10(6) ).

STUDY DESIGN AND METHODS

To develop a procedure allowing obtainment of purified CD34+ cells from LRFs with a good yield, white blood cell (WBC) recoveries after a 500-mL continuous or after sequential elution (50- or 20-mL fractions) were compared. Different WBC and mononuclear cell (MNC) centrifugation methods were tested to minimize their PLT contamination before the CD34+ cell immunomagnetic selection. Cell functionality was finally analyzed under various culture conditions.

RESULTS

The 20-mL back-flushing of LRFs allowed the most efficient WBC recovery. The next steps (110×g centrifugation, MNC separation on Ficoll, and washes) resulted in a cell suspension in which the lymphocyte recovery was approximately 76±10% and the PLT contamination below 1.6%. After immunomagnetic selection, 4×10(5) to 6×10(5) cells containing approximately 85% of functional CD34+ cells were obtained.

CONCLUSION

This procedure allows the easy, rapid (<5hr), and efficient preparation of large quantities of CD34+ cells having functional activities similar to those of CD34+ cells from other sources. Therefore, easily available and virally safe, LRFs represent an important and regular WBC source to work with human CD34+ cells, but also with other WBC types.

The platelet storage defect as measured in Costa Rica

The platelet storage defect emcompasses all untoward effects on platelet morphology structure and function with storage and the mechanisms responsible are not fully understood but are clearly multifactorial. The presence of swirling may correlate with acceptable pH values and the volume of suspending plasma to be effective to maintain a pH greater than 6,4 is between 75-85 g.

Comparative Study of Predeposit and Bedside Leucodepletion Filters

BACKGROUND

Removal of leucocytes from cellular blood components is associated with reduction of several transfusion associated adverse reactions.

METHODS

A total of 400 units of packed red blood cells (RBCs) were subjected to leucodepletion at room temperature and 4°C using different commercially available prestorage and bedside filters (Terumo Penpol Immugard III and Pall Medical BPF-4). Pre-filtration and post-filtration parameters were compared to assess the efficacy of prestorage leucodepletion vis-à-vis bedside leucodepletion and the requirement of universal leucodepletion.

RESULT

Mean post-filtration red cell recovery ranged from 88.49-93.49% with all bags showing more than 85% red cell recovery. Mean post-filtration residual leucocyte count ranged from 0.205 × 10(6)-0.338 × 10(6)/bag with all bags showing more than log 3 leucoreduction. Prestorage leucoreduction achieved by the polyurethane filter was better than that achieved by the polyester filter. Red cell recovery with the bedside filters at room temperature was significantly less than that with prestorage filters at either temperature.

CONCLUSION

This study suggests that prestorage leucoreduction is preferable over bedside leucoreduction and that polyurethane filters are better than polyester filters since leucodepletion achieved with the former is higher. We recommend selective log 3 leucodepletion using polyurethane prestorage filters for patients with specific indications.

Allogeneic blood transfusion in patients in Dukes B stage of colorectal cancer

The aim of this study is to evaluate influence of allogeneic blood transfusion on prognosis in patients in Dukes B stage of colorectal cancer. All patients with colorectal cancer who were admitted at our Department of Surgery between January 2000 and December 2004 were analyzed. One hundred fifty-one patients who fulfilled inclusion criteria were enrolled in further evaluation. B stage according to Dukes classification and curative resection were inclusion criteria. Exclusion criteria were polyposis syndromes, nonpolyposis syndromes, inflammatory bowel disease, autoimmune disease and previous blood transfusion. Patients were divided into two groups: Group 1 received ≤ 3 units of allogeneic blood transfusion and group 2 received >3 units of allogeneic blood transfusion. "Cutoff" value of 3 units of blood was defined according to our results and literature data. Follow-up was 5 year. There was no statistical difference between these groups in local recurrence (χ(2) = 0.009, P > 0.05) and distant metastasis (χ(2) = 0.44, P > 0.05). Also, the Kaplan-Meier survival curves were calculated, and long-rank test did not show a survival difference between these two groups (log rank = 0.075, P > 0.05). Postoperative complications are significantly more frequent in Group 2 (χ(2) = 4.67, P < 0.05). Multivariate logistic regression analysis confirmed that intraoperative blood transfusion more than three units had independent influence on local recurrence. Postoperative transfusion more than 3 units was statistically independent prognostic factor for metastasis and mortality. Overall transfusion less than 3 units of allogeneic blood does not influence the outcome of patients in Dukes B stage of colorectal cancer.

Estimating the cost of blood: past, present, and future directions

Understanding the costs associated with blood products requires sophisticated knowledge about transfusion medicine and is attracting the attention of clinical and administrative healthcare sectors worldwide. To improve outcomes, blood usage must be optimized and expenditures controlled so that resources may be channeled toward other diagnostic, therapeutic, and technological initiatives. Estimating blood costs, however, is a complex undertaking, surpassing simple supply versus demand economics. Shrinking donor availability and application of a precautionary principle to minimize transfusion risks are factors that continue to drive the cost of blood products upward. Recognizing that historical accounting attempts to determine blood costs have varied in scope, perspective, and methodology, new approaches have been initiated to identify all potential cost elements related to blood and blood product administration. Activities are also under way to tie these elements together in a comprehensive and practical model that will be applicable to all single-donor blood products without regard to practice type (e.g., academic, private, multi- or single-center clinic). These initiatives, their rationale, importance, and future directions are described.

Platelet Transfusion Therapy

This article provides guidelines for the appropriate use of platelet transfusions to reduce unnecessary transfusions, thereby avoiding transfusion-related risks to the patients and the costs of platelet therapy. Platelet products available for transfusion are whole blood derived platelet concentrates and apheresis platelets. Leukoreduced platelets can be used to reduce platelet alloimmunization, cytomegalovirus transmission, and febrile transfusion reactions, while gamma irradiation prevents transfusion-associated graftversus-host disease. Other topics discussed are the expected response to transfused platelets and reasons for poor responses related to alloimmunization, underlying disease state, clinical conditions, and drugs. Appropriate transfusion guidelines based on pretransfusion platelet count, platelet dose, and whether the transfusion is prophylactic or therapeutic are outlined. Identification, prevention, and management of adverse consequences of platelet transfusions and platelet refractoriness are discussed.

Portable microscopic cell counter for the determination of residual leucocytes in blood components

BACKGROUND AND OBJECTIVES

The accurate determination of residual white blood cell (WBC) in blood components is of considerable clinical importance, and a variety of methods have been devised for the counting of low levels of residual WBC. In this study, we evaluated the performance of microscopic cell counter with microchannel plastic chip (C-reader) with regard to its ability to quantify WBC in WBC-reduced red cell concentrates.

MATERIALS AND METHODS

In order to quantify residual WBC with the microscopic cell counter, WBC-reduced red cell concentrate was stained using propidium iodide. Three studies were performed: linearity, precision and correlation compared to those of manual Nageotte chamber counting and automatic flow cytometric methods.

RESULTS

Dilution experiments, conducted over a range of 0.7-712 WBC/microl, showed a linearity of r(2) > 0.999, with coefficient of variation values of < or = 15.6% and accuracy of 93.8% over all tested ranges. In comparison with the Nageotte chamber counting and flow cytometric methods, the correlation coefficients were r(2) > 0.995. The detection limit of this method was 0.24 WBC/microl. Total analysis time per sample was approximately 5 min.

CONCLUSION

The microscopic cell counter for residual WBC counting was determined to be efficient at the level of currently defined standards, with acceptable precision and accuracy. This method may prove useful for the quality assurance and control of WBC-depleted blood products.

A multistate cluster of red blood cell transfusion reactions associated with use of a leucocyte reduction filter

In 2000, the American Red Cross (ARC) received reports of unusual transfusion reactions of unknown aetiology among patients receiving leucocyte-reduced (LR) red blood cell (RBC) units in multiple distribution regions. We evaluated potential risk factors of reactions among patients who received LR-RBC transfusions. A case-patient was defined as any patient with onset of back pain while receiving an LR-RBC transfusion from 1 January to 25 May 2000. Controls were chosen randomly and selected in a 1:3 case : control ratio from healthcare facilities in which case-patients were transfused. Product-specific risk factors of reactions were further determined through nested case-control study, procedural review of blood collection facility and quality-control-testing record review of product processing. Reaction incidence rates were determined through ARC blood product distribution data by region of blood collection and processing. There were 29 reactions detected in patients who received transfusions in 13 healthcare facilities in five states. Eighteen case-patients and 78 controls were included in the case-control study. In univariate analysis, case-patients were more likely than controls to have a haematologic malignancy, to have received the transfusion as an outpatient, to have received an RBC transfusion within the previous 3 months, to have received medication used to prevent reactions or to diminish their intensity upon transfusion (i.e. premedication) or to have received LR-RBC units prepared with the HemaSure r\LS System(HS) rather than two other filters used. In multivariate analysis limited to recipients of HS-filtered RBC units, transfusion premedication [adjusted odds ratio (AOR) = 7; 95% confidence interval (CI) 1.4-37; P = 0.02] and transfusion as an outpatient (AOR = 5; 95% CI 1.1-20; P = 0.03) were independently associated with reactions. The rate of reported transfusion reactions was 2.0 reactions per 10 000 RBC units distributed. A multistate cluster of transfusion reactions was significantly associated with leucocyte filtration of RBC units prepared with a specific product, the HS filter. The reactions also were independently associated with premedication and transfusion as an outpatient; these may be surrogates for an increased risk of reaction or for greater likelihood of detection. The mechanism for these reactions has not been elucidated. This cluster of reactions underscores the importance of surveillance efforts to detect adverse events after transfusion, particularly when new methods to modify blood products are introduced.

Pneumonia as a complication of blood product transfusion in the critically ill: Transfusion-related immunomodulation (TRIM)

BACKGROUND

An increased risk of postoperative infection (including pneumonia) attributable to the receipt of allogeneic blood transfusion has been investigated as a possible manifestation of transfusion-related immunomodulation (TRIM) in 16 randomized controlled trials (RCTs) and approximately 40 observational studies.

OBJECTIVES

This review categorizes RCTs and observational studies with regard to the inference that they permit about possible mediators of TRIM-allogeneic white cells (WBCs), WBC-derived soluble mediators, and/or allogeneic plasma-and examines whether the totality of the clinical evidence supports an association between allogeneic blood transfusion and postoperative infection.

RESULTS

When all available studies are considered together in meta-analyses, three types of studies show no increased risk of postoperative infection in association with allogeneic blood transfusion: a) RCTs comparing recipients of buffy-coat-reduced and prestorage-filtered, WBC-reduced allogeneic red cells; b) RCTs comparing recipients of allogeneic and autologous blood; and c) observational studies comparing patients transfused before and after implementation of WBC reduction. RCTs comparing recipients of nonbuffy-coat-reduced and WBC-reduced red blood cells may point to a TRIM effect, but they cannot yet be subjected to formal meta-analysis.

CONCLUSIONS

No overwhelming clinical evidence has been presented to establish the existence of a TRIM effect that relates allogeneic blood transfusion to postoperative infection.

Massive transfusion as a risk factor for acute lung injury: Association or causation?

One of the most common clinical sequelae of massive transfusion is acute lung injury. In virtually all clinical settings, there is a very strong relationship between transfusion and acute lung injury that remains even after adjusting for potential confounders. Whether the association between transfusion and acute lung injury in these settings is a result of residual confounding or actually reflects a causal relationship is unknown. However, there are several potential mechanisms by which massive transfusion might predispose to lung injury: a) cognate antigen-antibody interactions (classic transfusion-associated lung injury); b) activation of nonspecific immunity through soluble mediators present in transfused blood; c) an increased risk of infection through transfusion-associated immunomodulation leading to sepsis and sepsis-induced lung injury; and d) volume overload in the face of increased permeability of the alveolar capillary membrane. Elucidating the precise causal mechanism operative in patients receiving massive transfusion has more than academic importance; it has direct implications for transfusion policy and practice.

Leucodepletion and Blood Products

BACKGROUND

Leucoreduction of blood products is increasingly being employed to produce blood products with residual WBCs < 5 × 10(6) per unit (99.9 percent or a log 3 leucoreduction). Clinical data suggests that non-haemolytic febrile transfusion reactions can be prevented by leucodepletion. The procedure also prevents alloimmunisation to HLA antigens in patients who will repeatedly require transfusion of blood/blood products.

METHOD

Of the methods available to reduce the number of WBC in blood products washing of red cells, freezing and deglycerolisation are effective and yield a product with only a 24 hour shelf life. Other methods such as leucodepletion filters are relatively inexpensive, simple and the final product has a normal shelf life. Modern generation of leucoreduction filters and apheresis machines can provide greater than 4 log reduction of WBC.

RESULTS

After the introduction of leucodepletion of blood for Thalassemics at our center in 2003, the incidence of non haemolytic febrile transfusion reactions (NHFTR) fell from 4% in 2002 to 1% in 2003.

CONCLUSION

In patients undergoing long-term blood transfusion therapy e.g. Thalassemics, alloimmunisation against the HLA antigens on donor white cells is prevented by leucodepletion and prevents NHFTRs.

Perioperative blood transfusion and outcome

PURPOSE OF REVIEW

As a result of advances in pathogen testing and transfusion standards over the last decade, the risk of disease transmission through allogeneic blood transfusions has decreased markedly. The effects of allogeneic blood transfusions on the immune system, however, have received more attention, as they appear to influence outcome. The following review summarizes the effects of allogeneic blood transfusions on selected outcome parameters and the influence of white blood cell reduction on these parameters.

RECENT FINDINGS

Adverse effects of allogeneic blood transfusions on outcome variables such as postoperative infection, cancer recurrence, pulmonary function, length of stay, and mortality have been shown in multiple trials, but most were not randomized or blinded. One proposed approach to reduce unwanted side-effects is to reduce the donor's white blood cell count before transfusion. This can be done either by individual bedside filtration or by pre-storage (or post-storage) universal white blood cell reduction. Studies investigating this approach have yielded conflicting results.

SUMMARY

Although the results of a number of studies suggest a negative impact of allogeneic blood transfusions on immune function and consequently outcome parameters, this has not been proven in rigorously controlled randomized trial, or in meta-analyses. Reduction of white blood cells might be beneficial in selected patient populations, but at this time does not appear warranted in the general surgical population. As universal white blood cell reduction is a very costly process, it probably should not be implemented until such a benefit is proven.

Decreased sepsis related to indwelling venous access devices coincident with implementation of universal leukoreduction of blood transfusions

BACKGROUND

Randomized trials and animal models demonstrate that leukoreduction of transfusions can reduce the risk of post-operative infections. We performed a retrospective study of sepsis related to indwelling venous access devices (line related infections) before and after the July 2000 implementation of universal leukoreduction.

METHODS

Line related infection data were collected from hospital infection control records for an 18-month period before and after July 2000. Transfusion histories were obtained from transfusion service records.

RESULTS

Line related infections decreased in number from 150 to 98 (-35%) in transfused patients after implementation of universal leukoreduction, whereas line related infections increased from 41 to 45 (+10%) in nontransfused patients (p = 0.04). This corresponded to a decrease from 5.3 to 3.3 infections/10,000 patient days in transfused patients (p = 0.002). The infection rate remained stable in nontransfused patients at 1.5 infections/10,000 patient days both pre- and postimplementation of universal leukoreduction. Quantitatively similar decreases (33-45%) were seen in transfused surgical, medical and pediatric patients.

CONCLUSIONS

A substantial and statistically significant decrease in line related infections occurred coincident with implementation of universal leukoreduction. These improved outcomes were observed in transfused but not nontransfused patients, across all clinical services, suggesting a causal relationship with universal leukoreduction.

Transfusion of the injured patient: proceed with caution

Transfusion of the injured patient with packed red blood cells (PRBCs) is a dynamic process requiring vigilance during the acute resuscitative and recovery phases postinjury. Although adverse events have been reported in 2% to 10% of injured patients, the advent of new detection techniques for viral pathogens has markedly decreased the risk of infectious transmission. However, transfusions are strongly associated with immunosuppression in the host, which may occur days after the initial injury and may lead to bacterial infections. Conversely, early transfusion of stored PRBCs, > 6 units in the first 12 h postinjury, contributes to an early state of hyperinflammation that is a strong, independent predictor of multiple organ failure (MOF) in those patients with intermediate injury severity scores. The roles of prestorage leukoreduction are also reviewed with respect to the promotion of both immunosuppression and hyperinflammation. We further summarize studies with hemoglobin substitutes, whose use may obviate many of the untoward events of transfusion and promise to lead to better outcomes for injured patients.

Pre-storage leucocyte depletion and transfusion reaction rates in cancer patients

Passenger leucocytes transfused with allogenic blood are responsible for potential adverse effects. The impact of pre-storage leucodepletion (in-line filtration) of all whole blood units on transfusion reaction rate among patients suffering from cancer was retrospectively studied, comparing all reactions following red blood cell (RBC) transfusions during 2 years of pre-storage vs. 2 years of selective (bedside) leucodepletion. During selective leucodepletion, 5165 RBC units - of which 2745 were bedside filtered units- were transfused to 866 patients. Twenty-eight reactions were recorded: 22 (15 in the bedside group) febrile non-haemolytic transfusion reactions (FNHTR) and six allergic reactions (five in the bedside group). The overall percentage of reactions was 0.54 (0.76 for bedside) and 0.42 for FNHTR (0.54 for bedside). During pre-storage leucodepletion, 4116 RBC units were transfused to 841 patients. Eleven reactions were recorded: four FNHTR and seven allergic reactions (urticaria). The percentage of reactions for transfused RBC units was 0.26 (0.09 for FNHTR). Comparison between pre-storage filtration and bedside filtration with regard to FNHTR showed an odds ratio of 2.80 (95% confidence interval = 0.83-14.87) for bedside filtration. The study suggests that, for transfused patients affected by cancer, pre-storage leucodepletion is more effective than selective (bedside) filtration in reducing the incidence of transfusion reactions (FNHTR).

Number needed to treat and cost of recombinant human erythropoietin to avoid one transfusion-related adverse event in critically ill patients

OBJECTIVE

To calculate the absolute risk reduction of transfusion-related adverse events, the number of patients needed to treat, and cost to avoid one transfusion-related adverse event by using erythropoietin in critically ill patients

DESIGN

Number needed to treat with sensitivity analysis.

SETTING

Teaching hospital.

PATIENTS

Hypothetical cohort of critically ill patients who were candidates to receive erythropoietin.

INTERVENTIONS

Using vs. not using erythropoietin to reduce the need for packed red blood cell transfusions.

MEASUREMENTS AND MAIN RESULTS

We used published estimates of known transfusion risks: transfusion-related acute lung injury, transfusion-related errors, hepatitis B and C, human immunodeficiency virus, human T-cell lymphotropic virus, and bacterial contamination, stratified by severity. Based on the estimated risk and frequency of transfusions with and without erythropoietin, we calculated the absolute risk reduction of transfusion-related adverse events, the number needed to treat, and cost to avoid one transfusion-related adverse event by using erythropoietin. The estimated incidence of transfusion-related adverse event was 318 permillion units transfused for all transfusion-related adverse events, 58 per million for serious transfusion-related adverse events, and 21 per million for likely fatal transfusion-related adverse events. The routine use of erythropoietin resulted in an absolute risk reduction of 191 per million for all transfusion-related adverse events, 35 per million for serious transfusion-related adverse events, and 12 per million for likely fatal transfusion-related adverse events. The number needed to treat was 5,246 to avoid one transfusion-related adverse event, 28,785 to avoid a serious transfusion-related adverse event, and 81,000 for a likely fatal transfusion-related adverse event. The total cost was $4,700,000 to avoid one transfusion-related adverse event, $25,600,000 to avoid one serious transfusion-related adverse event, and $71,800,000 to avoid a likely fatal transfusion-related adverse event. The magnitude of these results withstood extensive sensitivity analysis.

CONCLUSIONS

From the perspective of avoidance of adverse events, erythropoietin does not appear to be an efficient use of limited resources for routine use in critically ill patients.

Analysis of leukocyte binding to depletion filters: role of passive binding, interaction with platelets, and plasma components

Since limited knowledge exists on the mechanisms which regulate cell binding to leukocyte removal filter surfaces, we investigated the binding patterns of leukocytes to individual layers of leukocyte depletion filters. After passage of 1 unit of whole blood, blotting of isolated filter layers on glass slides or elution of cells from filter layers revealed that most leukocytes were located within the first 10 of a total of 28 filter layers, peaking at layers 6 to 8, with granulocytes binding on average to earlier filter layers than lymphocytes. Leukocytes preincubated with inhibitors of actin activation showed unchanged distribution between filter layers, suggesting that cytoskeletal activation does not significantly contribute to their binding. When leukocytes were directly incubated with single filter layers, binding of up to 30% of input cells was recorded in the absence of Ca(2+). Immunohistological analyses showed colocalization of platelets and leukocytes, with co-clustering of platelets and leukocytes. Monocytes and to some degree lymphocytes but not granulocytes competed with platelets for filter binding. Precoating of filter layers with individual plasma components showed that hyaluronic acid, plasma type fibronectin, and fibrinogen all increased the binding of leukocytes compared with albumin coating. In conclusion, leukocytes can bind passively to filters in a process which does not require Ca(2+), which is independent of cytoskeletal activation and which may depend on individual plasma components. These results are of importance when new selective cell enrichment or depletion strategies through specific filters are envisaged.

Real-time amplification of HLA-DQA1 for counting residual white blood cells in filtered platelet concentrates

BACKGROUND A real-time polymerase chain reaction (PCR) assay based on amplification of a conserved region of the HLA-DQA1 locus was developed and validated to assess its suitability in quantitating low levels of white blood cells (WBCs) in filtered platelet (PLT) concentrates (PCs).

STUDY DESIGN AND METHODS

To determine the detection limit, serial dilutions of nonfiltered PCs with known quantities of WBCs were prepared. The analytical sensitivity and accuracy of the assay was tested with WBC concentrations ranging from 300 to 0.03 per microL with real-time PCR and flow cytometry. In addition, 126 random PCs were investigated to assess the capacity of the PCR method to quantify residual WBCs in clinical specimens.

RESULTS

A sensitivity of 0.2 WBC equivalent per micro L (1.5 x 10(4) WBC equivalents/unit) was achieved. The assay was shown to be accurate and the HLA-DQA1 gene was reproducibly and consistently amplified in all tested samples (coefficient of variance of < 5%). Overall, the results of the PCR assay correlated well with those of the flow cytometry. The PCR assay detected a concentration of 3 WBCs per micro L (approximately 1 x 10(6) WBCs/unit) with 100 percent accuracy.

CONCLUSION

Real-time PCR is rapid, sensitive, accurate, and reproducible. Hence this approach may prove suitable in routine monitoring of residual WBCs in PCs.

Increasing hemoglobin oxygen saturation levels in sickle trait donor whole blood prevents hemoglobin S polymerization and allows effective white blood cell reduction by filtration

BACKGROUND Red blood cell (RBC) components from donors with sickle cell trait (Hb AS) often occlude white blood cell (WBC) reduction filters. Techniques were investigated to successfully filter Hb AS donor blood by increasing the Hb oxygen saturation with storage bags and conditions suitable for transfusion products.

STUDY DESIGN AND METHODS

Oxygenation kinetics were measured over 3 days in whole-blood units stored in standard-sized 600-mL polyvinylchloride (PVC) bags and whole-blood units divided into three equal parts and stored in standard-sized blood bags made from PVC, tri-2-(ethylhexyl)trimellitate (CLX) plastic, or Teflon. The filterability of Hb AS blood stored for 3 days was tested with whole-blood filters.

RESULTS

Oxygen saturation levels did not increase in full whole-blood units from donors without sickle cell trait during 3 days of storage in 600-mL PVC bags. In divided Hb AS whole-blood units stored for 3 days, oxygen saturation levels increased from baseline levels of 45 to 56, 66, and 94 percent after storage in 600-mL PVC, CLX, and Teflon bags, respectively (n = 5, p < 0.02), and all components filtered completely. When full Hb AS whole-blood units from eight donors were stored for 3 days in 1.5-L CLX bags, all units filtered completely, but one had a high residual WBC count.

CONCLUSION

Storage of Hb AS whole blood in large-capacity oxygen-permeable bags increases oxygen tension and allows more effective WBC reduction by filtration.

Reduction of febrile but not allergic reactions to RBCs and platelets after conversion to universal prestorage leukoreduction

BACKGROUND

Between January 1995 and November 1998, at Yale-New Haven Hospital, 25 percent of RBCs transfused were processed through prestorage or bedside leukoreduction filters, chosen on a per patient basis (selective leukoreduction [SLR]). Between January 1995 and July 1999, 30 percent of platelet concentrates (PCs) were infused through bedside leukoreduction filters. In an attempt to decrease febrile nonhemolytic transfusion reactions (FNHTR), a change was made from SLR to universal prestorage leukoreduction (UPL) for RBCs between November 1998 and December 1999 and for random donor PCs between July 1999 and January 2000. FNHTR and allergic transfusion reactions (ATR) reported from January 1995 through December 2002 were reviewed.

STUDY DESIGN AND METHODS

For retrospective observational analysis, blood bank data were available on the number of RBCs and PCs transfused, percent products leukoreduced, and rate of FNHTR and ATR from 1995 through December 2002. After dividing this time period into three phases (SLR, transition, and UPL), these data were evaluated using odds ratio (ORs) and Student's t tests.

RESULTS

A total of 145,369 RBCs and 137,982 PCs (29,487 PC pools) transfused between January 1995 and December 2002 were evaluated. For RBCs, the relative FNHTR rate decreased 47.1 percent, from 0.34 percent (SLR) to 0.18 percent (UPL) (p < 0.0001). ATR rates for RBCs showed 0.09 percent for both SLR and UPL groups (p > 0.05, NS). For PCs, the FNHTR relative rate decreased 93.1 percent, from 2.18 percent for SLR to 0.15 percent for UPL (p < 0.0001). Rates for ATR were 0.49 percent (SLR) and 0.35 percent (UPL) (p > 0.05, NS).

CONCLUSIONS

A significant decrease in the frequency of posttransfusion FNHTR, but not ATR, for RBCs and PCs followed introduction of 100-percent UPL. The data support the hypothesis that the practice of UPL of RBCs and PCs decreases the frequency of FNHTR and thus improves patient care over the practice of selective leukoreduction.

Universal leukodepletion of blood components results in a significant reduction of febrile non-hemolytic but not allergic transfusion reactions

BACKGROUND

Universal leukodepletion of blood components to prevent acute non-hemolytic transfusion reactions (NHTRs) is still a subject of debate.

PATIENTS AND METHODS

Transfusion-associated NHTRs observed at our hospital in the last 6 years were retrospectively analyzed. Buffy-coat depleted red blood cells (bc-RBCs), and if indicated, leucodepleted post-storage (ld-RBCs) were initially used. In April 1997, universal leukodepletion was implemented at our hospital, and thereafter only prestorage ld-RBCs were used. All platelet concentrates transfused during this time were prestorage filtered single-donor apheresis platelets (SDAPs).

RESULTS

A total of 163,090 blood products were transfused from April 1995 to April 2001 (bc-RBC: n=34,040 units; ld-RBC: n=66,967; SDAP: n=14,516; FFP: n=47,567). The number of post-transfusion febrile NHTRs occurring with each blood product was 65 (0.19%) for bc-RBCs, 8 (0.16%) for post-storage ld-RBCs, 16 (0.03%) for prestorage ld-RBCs, 16 (0.11%) for SDAPs, and 10 (0.02%) for FFP. Allergic reactions (n=116) were most frequently observed after SDAP transfusion (0.32%) and occurred at a similarly low rate after transfusion of all other blood components (0.03-0.08%).

CONCLUSION

In conclusion, acute NHTRs rarely occur after the use of leukodepleted blood components. Prestorage appears to be more effective than post-storage leukodepletion in preventing febrile reactions following a blood transfusion.