Six filters for the removal of white cells from red cell concentrates, evaluated at 4 degrees C and/or at room temperature

The effects of leukoreduction on canine blood unit weight and processing time

BACKGROUND

Despite a lack of strong evidence of benefit, leukoreduction is employed to decrease the risk of leukocyte-induced transfusion reactions. However, the impact of leukoreduction on blood bank costs and inventory management is not well understood. The purpose of this study was to determine whether leukoreduction of whole blood increases total processing time and weight loss from packed red blood cells (PRBCs) and plasma relative to bags created from nonleukoreduced whole blood.

KEY FINDINGS

A total of 68 canine whole blood collections were divided equally into leukoreduced and nonleukoreduced groups (N = 34 in each). There was no significant difference between groups in mean PRBC or plasma unit weights or processing times. Leukoreduced PRBC bags lost a significantly greater proportion of weight during processing than did nonleukoreduced PRBC bags (P < 0.01), which is attributed to red and white blood cells lost in the filtration process.

SIGNIFICANCE

Leukoreduction did not lead to a significant increase in processing times or smaller PRBCs or plasma bags compared to nonleukoreduced bags. The blood remaining in the leukoreduction filter following filtration is primarily composed of red blood cells, with minimal plasma retained.

Laboratory and clinical comparison of the efficacy of prestorage leukoreduction of red cells at cold versus room temperature

BACKGROUND

The temperature at which filtration takes place has been reported to influence the efficacy of leukoreduction. We aimed to compare the residual leukocyte count (RLC) in red cell units (RCUs) filtered at cold (CT) versus room temperature (RT) and to assess whether this correlates clinically with a difference in the incidence of acute transfusion reactions (ATRs).

METHODS AND MATERIALS

In the first part of the study, whole blood units collected were randomly allocated for subsequent filtration at CT and RT, respectively. RLC postfiltration was assessed using flow cytometry. The second part of the study was a nonrandomized clinical trial in which incidence of ATR was compared between RCUs filtered at RT and CT for 6 months each.

RESULTS

Thirty-five RCUs each underwent leukofiltration at CT and RT, respectively. The median RLCs in the filtered units at CT and RT were 0.02 × 10⁶ and 0.1 × 10⁶ leukocytes/unit, respectively (p = .0001), with no difference in red blood cell (RBC) recovery (p = .41). During the second part, 3455 RCUs filtered at RT and 3539 RCUs filtered at CT were transfused to patients. The rate of febrile non-hemolytic transfusion reaction (FNHTR) among transfused patients was less with units filtered at CT (1 per 2000 transfusions) in comparison to RT (1 per 588 transfusions). The difference was, however, not significant (p = .14).

CONCLUSION

If change in temperature alone can cause significant reduction in leukocytes, then it is a simple way to curtail the rate of this common yet unpleasant reaction and reduce the reaction rate at minimal cost.

Does Transfusion of Red Blood Cells Impact Germline Genetic Test Results?

Purpose: molecular testing is often indicated for recently transfused patients. However, there are no guidelines regarding the potential interference from donor DNA or whether it is necessary to wait for a period of time post-transfusion prior to genetic testing. While the majority of patients are transfused in the non-trauma setting using leukoreduced (LR) red blood cell products, the degree of leukoreduction varies among centers and is not universally practiced. Methods: whole blood units collected from anonymous donors were used in an in vitro transfusion model. One unit was split: half being leukoreduced simulating a leukopenic recipient and half left untreated. Donors were simulated by leukoreduced, partially leukoreduced (PLR), or non-leukoreduced units, transfused in 2, 5, or 16 unit equivalents. DNA from the combinations were subjected to short tandem repeat (STR) analysis for chimerism detection. Results: donor DNA was not detectable in any of the LR combinations, but detected in the PLR combinations, ranging from 0.1 to 1.5% donor DNA in the immunocompetent recipient and 6.3–27.8% in the leukopenic recipient. Non-LR donor DNA was also detected (13–95%). Conclusion: donor-derived DNA from leukoreduced blood products is unlikely to interfere with the interpretation of germline genetic testing in immunocompetent recipients but may interfere in immunocompromised recipients.

Prospective Comparative Quality Control Study of a Novel Gravity-Driven Hollow-Fiber Whole Blood Separation System for the Production of Canine Blood Products

The aim of this prospective study was to compare quality of blood products produced either by a novel gravity-driven hollow-fiber separation system (HF) or by centrifugation (C). Whole blood was obtained from 31 healthy non-greyhound canine blood donors and separated into fresh frozen plasma and packed red blood cells using either HF or C in a university teaching hospital. Red blood cell (RBC) count, albumin and fibrinogen concentration, prothrombin time (PT), activated partial thromboplastin time (aPTT) and coagulation factor activity (FV, FVIII), von Willebrand Factor (vWF), and antithrombin activity were assessed. Plasma obtained with the HF showed a significantly higher median PT (9.4 vs. 7.9 s, P = 0.0006) and aPTT (14.9 vs. 13.1 s, P = 0.0128) than plasma prepared with C. Lower albumin (21.7 vs. 23.5 g/l, P = 0.0162) and fibrinogen (1.0 vs. 1.5 g/l, P = 0.0005) concentrations and activities of FV (105 vs. 114%, P = 0.0021) and antithrombin (104 vs. 117%, P = 0.0024) were seen in blood products obtained with the HF. In contrast, vWF was not affected by the method of plasma separation. Compared to HF, RBC count as well as hematocrit were not significantly higher (8.0 vs. 8.9 10¹²/l, P = 0.1308; 0.57 vs. 0.62 l/l, P = 0.0736) when blood products were prepared with C. In conclusion, higher quality of blood products especially regarding coagulation parameters and RBCs was achieved by using C compared to HF. Despite the statistical significances, however, the clinical relevance has to be further elucidated. Nevertheless, HF provides an alternative to produce blood products if a centrifuge is not available.

Gewinnung, Herstellung und Lagerung von Blut und Blutkomponenten

Blutspender leisten einen wertvollen Dienst für die Gemeinschaft: Die ständige Verfügbarkeit von Blutkomponenten ist zur unverzichtbaren Voraussetzung für viele Bereiche der Medizin geworden. Nicht nur die Gewinnung und Aufarbeitung von Blut und Blutbestandteilen zur Sicherstellung einer qualitativ wie quantitativ guten Versorgung, sondern auch die kompetente Betreuung der Spender ist eine der großen Aufgaben der Transfusionsmedizin.

Characterization of blood components prepared from whole-blood donations after a 24-hour hold with the platelet-rich plasma method

BACKGROUND

The preparation of platelet (PLT) concentrates (PCs) from PLT-rich plasma (PRP) requires that whole blood (WB) be processed within 8 hours of collection. Increasing WB storage time to 24 hours would be logistically attractive. This study compares the in vitro quality of blood components prepared from WB stored for 8 and 24 hours at room temperature before processing with the PRP method.

STUDY DESIGN AND METHODS

WB units were collected from ABO-matched blood donors. To reduce individual variations, paired donations were drawn in parallel, pooled, and split back in the collection bag. One unit was held for 6 to 8 hours and the other for 22 to 24 hours at 20 to 24 degrees C. Prestorage leukoreduced components were prepared with the PRP as intermediate product and analyzed during storage.

RESULTS

RBC units prepared after an 8- or 24-hour hold were comparable in terms of hemolysis, sodium, pH, and ATP levels. RBC 2,3- diphosphoglycerate (2,3-DPG) was significantly lower in RBCs prepared from 24-hour hold donations immediately after processing but not after 20 days of storage. Residual white blood cells were approximately fivefold higher (p < 0.05) in 24-hour RBC units. For PCs, measurements for glucose, ATP, lactate, pH, extent of shape change, hypotonic shock response, and CD62p activation were similar. No differences were observed in the von Willebrand factor, factor (F)V, FVIII, and fibrinogen content of fresh-frozen plasma.

CONCLUSIONS

The decrease in FVIII and RBC 2,3-DPG can be acceptable as a compromise to improve blood component logistics, but leukoreduction efficiency must be improved before considering the adoption of an overnight storage of WB before PRP processing.

Prestorage leukoreduction and low-temperature filtration reduce hemolysis of stored red cell concentrates

BACKGROUND

Universal prestorage leukoreduction in Canada created the perception that stored red cells (RBCs) are more hemolyzed than their unfiltered predecessors. A pool-split design tested the effects of leukoreduction on hemolysis of stored RBCs.

STUDY DESIGN AND METHODS

Two ABO-matched units were pooled, divided, and then processed into leukoreduced (LR) and nonleukoreduced (NLR) units with the Pall LT-WB or RC-PL systems and sampled during standard processing and storage for testing of sterility, counts, hemolysis, and osmotic fragility.

RESULTS

Room temperature (RT) filtration of 10 pairs of LT-WB-LR and -NLR units showed significantly different percentage of hemolysis (0.39%) and osmotic fragility (0.643%) at 42 days. Cold-stored and -filtered units (2 days at 4 degrees C before processing) were less hemolyzed, but showed a similar proportional decrease of hemolysis in LR units (0.13% vs. 0.25% at 42 days). RBCs from RC-PL systems showed the lowest hemolysis although there was a filtration effect (0.05% vs. 0.12%, 42 days). Osmotic fragility paralleled hemolysis. Segment samples gave inaccurate results. Two-day prefiltration cold storage reduced hemolysis from 0.36 to 0.07 percent (42 days, p < 0.001). RT-LR hemolysis became significantly higher by Day 10 and 4 degrees C LR by Day 12. NLR units showed hemolysis by Day 7. LR units filtered cold were less hemolyzed (p < 0.05) than RT-LR but osmotic fragility was unchanged.

CONCLUSIONS

LR-RBCs prepared by any of three methods (LT-WB, RT or cold; RC-PL), filtered at 4 degrees C, were less hemolyzed during storage than nonfiltered concentrates: 4 degrees C leukoreduction is beneficial for RBCs and does not cause hemolysis or enhance fragility.

Mechanisms Responsible for Delayed and Immediate Hemolytic Transfusion Reactions in a Patient with Anti‐E + Jkb+ Diband Anti‐HLA Alloantibodies

Immediate hemolytic transfusion reactions (IHTR) occurred in the course of delayed hemolytic transfusion reactions (DHTR). An 84-year-old man had received a blood transfusion 20 years ago. Progressive anemia developed, because of continuous bleeding from a bladder tumor. He was transfused with concentrated red blood cells (CRC) which were Rh-E antigen negative, because he had anti-E antibodies (day 0). He received CRC on day 3, and underwent resection of bladder tumor on day 6. Although crossmatch-compatible CRCs were prepared for the operation, those were not required and were kept in a refrigerator in the ward. On day 9, when a CRC kept in the ward was transfused, he suddenly had a IHTR. In order to analyze a mechanism of IHTR, the anti-Jk(b) and anti-Di(b) antibodies, anti-HLA antibodies and the concentrations of inflammatory cytokines were measured in serum samples. The anti-Jk(b) and anti-Di(b) antibodies increased prior to IHTR experienced on day 9. The concentrations of IL-6 and IL-1beta increased from day 2, while the concentration of IL-8 increased from day 7. The anti-HLA class I antibody could be detected 2 days before IHTR. Thus, the anti-Jk(b) and anti-Di(b) antibodies induced the production of inflammatory cytokines and symptoms of DHTR and IHTR. The anti-HLA class I antibody could be produced in spite of using the filer for removing leukocytes, and may take part in the induction of IHTR. Further, blood products should be transfused soon after completing a crossmatch test in patients with anti-RBC alloantibodies.

Multicenter evaluation of a whole-blood filter that saves platelets

BACKGROUND

Whole-blood (WB) leukoreduction filters in current use retain the majority of PLTs. A new whole-blood filter, which retains significantly fewer of the PLTs (or saves PLTs [WB-SP]), has been developed. The performance characteristics of the WB-SP filter have been evaluated in a multicenter study.

STUDY DESIGN AND METHODS

A total of 617 units of WB was collected into quadruple bag sets with an integrated WB-SP filter, leukoreduced, and processed into leukoreduced RBCs (LR-RBC), plasma (LR-PL), and buffy coats (LR-BC) from which, pooled, leukoreduced, PLT concentrates (LR-PCs) were produced. Recovery, yield, and residual WBCs were assessed in prepared blood components.

RESULTS

The median residual WBC number in the LR-RBCs was 0.05 x 10(6) (range, <0.05-3.8), exceeding 1 x 10(6) in 0.6 percent of the units. Median Hb content in LR-RBC was 50 g (range, 34-72), reflecting a final RBC recovery of 81 +/- 6 percent. The median WBC content of the LR-PC was 0.05 x 10(6) (range, <0.05-0.28), with none exceeding 1 x 10(6). The median PLT content of the LR-PC, per individual donation, was 6.4 x 10(10) (range, 4.1-10.7), representing a final recovery of 62 +/- 10 percent. The mean FVIII activity was 104 +/- 25 percent and 83 +/- 11 percent in plasma separated from fresh or overnight stored WB, respectively.

CONCLUSION

Use of the WB-SP filter makes it possible to obtain three leukoreduced blood components with only one filtration step. The WB-SP filter showed good leukoreduction performance and recovery of all blood components including PLTs.

Evaluation of the Abbott Cell-Dyn 4000 hematology analyzer for detection and therapeutic monitoring of Plasmodium vivax in the Republic of Korea

The Cell-Dyn 4000 automated hematology analyzer (CD4000) has the ability to detect malaria patients, but it remained unclear whether it could detect persistent malaria post-treatment. To investigate this, we used the CD4000 to evaluate 68 Korean patients with Plasmodium vivax malaria, and control groups of 50 patients with fever and 50 asymptomatic patients. The results from the instrument-generated scatter plot (derived by laser light depolarization) were compared with microscopy results. During the initial diagnosis, the sensitivity of the CD4000 in detecting malaria was 91.2%. On day 3 of follow-up, the CD4000 results matched those from microscopy by 96.7%. Malaria was not detected by either method beyond 14 days post-presentation. Interestingly, the atypical depolarizing events, which typify the presence of malaria in the analyzer, were highly correlated with the levels of parasitaemia in serially diluted samples of the leucocyte-depleted blood, and the CD4000 detected parasites down to the level of 288 +/- 17.7/microl. Our findings suggest that the phenomenon of atypical light depolarization could be influenced by parasitaemia levels, and be used as a screening method for P. vivax malaria patients, as well as for the therapeutic monitoring.

Altering interface detector positioning in combination with prestorage filtration to achieve a better quality of single donor platelet concentrates using the CS 3000 Plus blood separator

The interface detector (ID) is an optical density sensor that affects the quality of single donor platelet collection using the CS 3000 Plus blood separator. The purpose of this study was to evaluate the effect of altering ID position on platelet yields and the contamination of leukocytes (WBC) in platelet concentrates (PCs). Dual-needle apheresis procedures (n = 93) were performed using an A35 collection chamber. Plateletpheresis products were separated according to interface detector offset (IDO) positioning into four groups: A: IDO = 6 (n = 33), B: IDO = 10 (n = 28), C: IDO = 12 (n = 18), D: IDO = 18 (n = 14). For 32% of the collections, the closed system apheresis kit with integral Sepacell filter (Baxter) was used and 33% of them were leukodepleted using the LRP-6 (PALL) filter. Our results showed that: (1) Although the mean blood volume and the time of apheresis were significantly higher, the mean platelet (PLT) yields were significantly lower in PCs of group A as compared to all other groups (P < 0.0001). (2) The mean WBC content was significantly higher in PCs of group D as compared to all other groups (P < 0.0001). (3) With the LRP-6 filter, a significantly higher WBC reduction as well as PLT loss in PCs was observed as compared to Sepacell leukapheresis filter. A higher PLT loss was observed with both filters when leukoreduction was performed within the first 6 hours as compared to 24 hours after the procedure. Conclusively, an IDO setting of 10 or 12 results in better platelet yields in PCs without increasing the WBC contamination. An IDO positioning of 18 or higher must be avoided or should be always combined with PCs leukodepletion. Finally, the best timing for leukoreduction is 24 hours after the plateletpheresis.

WBC filtration of whole blood after prolonged storage at ambient temperature by use of an in-line filter collection system

BACKGROUND

Before-storage WBC reduction by filtration appears to be an effective way to prevent transfusion-associated complications. It also has superiority over WBC reduction at the time of transfusion (bedside), due to the many variables associated with such practice and the difficulty in performing adequate quality control. To determine the adaptability of collection systems containing in-line filters to the current blood collection strategy, the feasibility, efficiency, and quality of before-storage WBC reduction of whole blood (WB) units were evaluated, following their prolonged storage at ambient temperature prior to component preparation, by use of an integral in-line filter.

STUDY DESIGN AND METHODS

Blood was collected from random donors into quadruple blood pack units with an integral in-line filter and divided into three groups, according to storage conditions. WBC reduction was performed at room temperature, on WB units after storage at ambient temperature either for less than 8 or up to 18 hours on 1,4-butanediol cooling trays or for 18 hours in the cold.

RESULTS

All the filtration procedures met the AABB threshold of less than 5 x 10(6) residual WBCs per unit and the European requirements for WBC counts of less than 1 x 10(6) WBCs per unit. The average filtration time was less than 22 minutes in all units studied. Filtration time and blood flow rate were both significantly longer, and RBC loss was significantly higher in WB units that were filtered after prolonged storage in the cold.

CONCLUSIONS

Adequate before-storage WBC reduction can be achieved when performed on WB units, which were stored at ambient temperature for 18 hours, by use of an in-line filtration system. The procedure, performed under relatively simple logistics, results in good-quality, standard components, which require no further modifications when supplied to the transfusion services.

Prestorage WBC filtration of RBC units with soft-shell filters: filtration performance and impact on RBCs during storage for 42 days

BACKGROUND

The introduction of universal WBC filtration of RBCs prior to storage is currently under consideration in many countries, as it is thought to minimize the incidence of transfusion-associated adverse effects. Centrifugation of blood containers with newly developed soft-shell WBC filters is more convenient, and so of great interest.

STUDY DESIGN AND METHODS

Two different quadruple blood pack systems with integrated soft-shell WBC filters were compared (Sepacell OptiPure RC, Baxter Biotech, vs. LCR 5, Maco Pharma). Buffy coat-depleted RBC units were investigated from whole-blood donations that were held for 2 to 3 hours before centrifugation and subsequent filtration at 22 degrees C (Group 1, OptiPure RC, 450 mL; Group 2, LCR 5, 450 mL; Group 3, OptiPure RC, 500 mL; Group 4, LCR 5, 500, mL, n = 12 per group). Filtration performance was analyzed, and the impact of WBC filtration on hemolysis rate, Hb content, pH, supernatant potassium, ATP, and 2,3 DPG was investigated weekly during storage for 42 days.

RESULTS

Filtration reduced the WBC count by 4.4 to 5.1 log. Mean +/- SD Hb content was 44.7 +/- 3.0, 41.2 +/- 3.3, 53.1 +/- 5.0, and 51.5 +/- 6.3 g per unit, respectively, with a corresponding mean RBC recovery after filtration of 71.0 +/- 3.0, 68.3 +/- 3.3, 76.6 +/- 1.7, and 68.9 +/- 4.5 percent. WBC filtration resulted in a significant reduction of Hct (0.10-0.14) in all four groups. Investigation of all RBC storage variables revealed acceptable values throughout the storage for 42 days.

CONCLUSION

WBC filtration with two newly developed soft-shell filters showed acceptable WBC-reduction efficacy without any difference between filter types in buffy coat-depleted RBCs from 450- and 500-mL whole-blood donations. However, the application of both filters resulted in an unacceptably low RBC recovery after filtration, which was particularly evident with the LCR5 filter. Our findings raise concern that WBC reduction with these filters may result in the production of RBCs with an inappropriately low Hb concentration.

In vivo and in vitro characteristics of double units of RBCs collected by apheresis with a single in-line WBC-reduction filter

BACKGROUND

A novel apheresis procedure for a blood separator (MCS+, Haemonetics) enables the collection of 2 WBC-reduced RBC units in a single donation by using one disposable set with one in-line WBC-reduction filter (RC2H, Pall Corp.). The objective of this study was to evaluate the filtration performance in connection with different prefiltration RBC storage conditions and with the in vitro and in vivo storage quality of the filtered units.

STUDY DESIGN AND METHODS

Sixty-six 2-unit RBC collection and gravity-filtration procedures were completed at three sites, resulting in 132 RBC units. Filtration of the double RBC units was performed at room temperature (RT) within 8 hours of collection (n = 36) and under refrigeration (1-6 degrees C) for up to 24 hours (n = 10) and 72 hours (n = 20) before filtration. RBC quality was compared to that of nonfiltered apheresis RBC units (n = 10).

RESULTS

Median filtration time was 6.5 and 14 minutes for units stored at RT and under refrigeration, respectively. All 132 RBC units had residual WBC counts <0.4 x 10(6). The refrigerated units showed a greater mean log reduction in WBCs: 5.06 +/- 0.16 (24 hour) and 4.74 +/- 0.48 (72 hour), respectively, than did RT units: 4.47 +/- 0.28 (p<0.05). RBC loss was less than 12 percent in all cases (mean, 7.8 +/- 1.8%). Minimal differences in volume were observed between the paired RBC units. In vitro RBC storage characteristics of the filtered units were as expected and similar to those of the nonfiltered units. For RBC units held at RT (n = 24), the mean in vivo 24-hour recovery was 81.8 +/- 8.4 percent (double-label).

CONCLUSION

Satisfactory filter performance in terms of WBC removal and RBC loss was observed with all 66 procedures, irrespective of storage conditions before filtration.

WBC reduction in RBC concentrates by prestorage filtration: multicenter experience

BACKGROUND

As universal leukocyte (WBC) reduction (ULR) is being considered as a new standard, few data are available on the performance of WBC-reduction filtration in routine practice. The performance of WBC-reduction in RBCs, using varied filtration practices, in meeting the current FDA requirement (<5 x 10(6)), Council of Europe (EC) recommendation, the proposed FDA requirement (<1 x 10(6)), and a more stringent proposal (<5 x 10(5)) for residual WBCs per RBC unit was assessed and compared.

STUDY DESIGN AND METHODS

Participating facilities were the 11 sites of the Viral Activation Transfusion Study (VATS), a prospective study of the impact of transfusion with and without WBC-reduction on survival and HIV viral load in HIV-1-infected patients. Patients randomly assigned to undergo WBC reduction were required to receive RBCs < or =14 days old that had undergone prestorage (within 72 hours of collection) WBC-reduction filtration by a method devised to achieve a postfiltration WBC count of <5 x 10(6). Residual WBC quantitation was performed by PCR in the central VATS laboratory by using frozen WBC-reduced RBC samples obtained at issue for transfusion.

RESULTS

A total of 1869 WBC-reduced RBC units were studied. Filtration practices varied within and between sites. There were significant differences in mean residual WBC counts at the 11 sites (p<0.001). Among the WBC-reduced RBC units, 0.8 percent exceeded 5 x 10(6) WBCs per unit, 8.3 percent exceeded 1 x 10(6) WBCs per unit, and 14.3 percent exceeded 5 x 10(5) WBCs per unit.

CONCLUSION

Residual WBCs in WBC-reduced RBC units vary within and between sites. WBC reduction was successful, in that over 99 percent and 91 percent of VATS WBC-reduced RBC units met US and EC thresholds, respectively. However, the small but measurable failure rate indicates that not every unit will meet these guidelines.

Number of RBC units and rate of transfusionto anemic HIV-positive patients assigned to receiveWBC-reduced or non-WBC-reduced RBCs: the viral activation transfusion study experience

BACKGROUND

It is known that the use of filtration to reduce WBCs in RBC units is associated with a 6- to 15-percent loss of RBCs. It is not known if the use of such WBC-reduced RBCs results in an increased need for RBC units or in the transfusion of more units per year to patients with anemia.

STUDY DESIGN AND METHODS

In the multicenter Viral Activation Transfusion Study (VATS), anemic HIV-positive patients were randomly assigned to receive either WBC-reduced or non-WBC-reduced RBCs. The number of RBC units transfused per patient and the rate of RBC use were studied. All RBC units given after the enrollment transfusion were counted, until the end of follow-up or the occurrence of bleeding (receiving >5 RBCs within 2 consecutive days).

RESULTS

As expected, the WBC-reduced RBC units in VATS were lighter in weight than the non-WBC-reduced units (median weight: WBC-reduced, 300 g; non-WBC-reduced, 330 g; p<0.0001). After the enrollment transfusion, 258 WBC-reduced arm patients received 1279 units of RBCs (average, 5.0 units/patient, median, 2 units) while 262 patients in the non-WBC-reduced arm received 1111 RBCs (4.2 units/patient; median, 2 units). The number of units transfused for anemia was slightly greater in the WBC-reduced arm, but the difference was not significant (p = 0.41). Similarly, the rate of RBC use was somewhat higher in the WBC-reduced arm, but the difference was not significant (p = 0.14). The median was 2.3 units per patient per year of follow-up in the WBC-reduced arm; the median in the non-WBC-reduced arm was 1.2 units.

CONCLUSION

This study confirms that WBC-reduced RBC units are significantly lighter in weight than non-WBC-reduced RBCs. However, in the setting of a large, randomized, blinded study of transfusion for anemia, the smaller size of the WBC-reduced RBC units had no significant effect on the number of RBC units transfused or on the rate at which RBC units were used. In this study, the frequency of blood transfusion may have had a greater relationship to the frequency of routine, scheduled appointments or transfusion orders for a specified Hb trigger than to the actual Hb content of the unit.

Influence of temperature, filter wettability, and timing of filtration on the removal of WBCs from RBC concentrates

BACKGROUND

The efficacy of the removal of WBCs from buffy coat-reduced RBC concentrates by filtration is determined by many variables. The aim of this study was to investigate the influence of the filtration temperature, the wettability of the filter material, and the timing of the filtration after collection.

STUDY DESIGN AND METHODS

The investigation used commercially available filters: 3 dry "online" filters (Cellselect FR, Fresenius Hemocare; BioR-01-max, Fresenius; Leucoflex LCG1, MacoPharma) and one wet "inline" filter (Leucoflex LCR4, MacoPharma) that contained saline-adenine-glucose-mannitol additive solution for RBCs and differed from the online version only in wettability. After buffy coat removal and suspension in saline-adenine-glucose-mannitol, filtrations were performed immediately at room temperature (RT) and after 2 hours' storage of the RBC concentrates at 4 degrees C, while the Leucoflex LCR4 was also tested after 24 hours' storage of the RBC concentrates at 4 degrees C. Sets of 12 pooled experiments were performed to prevent donor-dependent differences.

RESULTS

The Cellselect FR gave significantly better WBC removal from RBC concentrates at 4 degrees C than at RT, with residual WBCs of 1.44 +/- 0.58 x 10(6) and 2.78 +/- 1.23 x 10(6), respectively (p<0.001). The BioR-01-max gave no significant difference: 0.62 +/- 0.27 x 10(6) WBCs (at 4 degrees C) versus 0.61 +/- 0.25 x 10(6) WBCs (at RT). Filtration with the Leucoflex LCG1 resulted in 0.06 +/- 0.03 x 10(6) and 0.07 +/- 0.07 x 10(6) WBCs at 4 degrees C and RT, respectively, which is not a significant difference. The Leucoflex LCR4, however, gave 2.08 +/- 0.84 x 10(6) WBCs at RT, 0.52 +/- 0.44 x 10(6) WBCs at 4 degrees C after 2 hours' cooling, and 0.05 +/- 0.10 x 10(6) WBCs at 4 degrees C after 24 hours' cooling (all p<0.001).

CONCLUSION

Temperature, filter wettability, and timing of filtration after collection influence the efficacy of a filter for RBC concentrates. These variables need to be established, validated, and controlled before a filter can be selected for routine use.