Comparison of COBE white cell-reduction and standard plateletpheresis protocols in the same donors

Platelet Vascular Endothelial Growth Factor is a Potential Mediator of Transfusion-Related Acute Lung Injury

Objective

The occurrence of non-hemolytic transfusion reactions is highest with platelet and plasma administration. Some of these reactions are characterized by endothelial leak, especially transfusion related acute lung injury (TRALI). Elevated concentrations of inflammatory mediators secreted by contaminating leukocytes during blood product storage may contribute to such reactions, but platelet-secreted mediators may also contribute. We hypothesized that platelet storage leads to accumulation of the endothelial permeability mediator vascular endothelial growth factor (VEGF), and that intravascular administration of exogenous VEGF leads to extensive binding to its lung receptors.

Methods

Single donor, leukocyte-reduced apheresis platelet units were sampled over 5 days of storage. VEGF protein content of the centrifuged supernatant was determined by ELISA, and the potential contribution of VEGF from contaminating leukocytes was quantified. Isolated-perfused rat lungs were used to study the uptake of radiolabeled VEGF administered intravascularly, and the effect of unlabeled VEGF on lung leak.

Results

There was a time-dependent release of VEGF into the plasma fraction of the platelet concentrates (62 ± 9 pg/ml on day one, 149 ± 23 pg/ml on day 5; mean ± SEM, p<0.01, n=8) and a contribution by contaminating leukocytes was excluded. Exogenous 125I-VEGF bound avidly and specifically to the lung vasculature, and unlabeled VEGF in the lung perfusate caused vascular leak.

Conclusion

Rising concentrations of VEGF occur during storage of single donor platelet concentrates due to platelet secretion or disintegration, but not due to leukocyte contamination. Exogenous VEGF at these concentrations rapidly binds to its receptors in the lung vessels. At higher VEGF concentrations, VEGF causes vascular leak in uninjured lungs. These data provide further evidence that VEGF may contribute to the increased lung permeability seen in TRALI associated with platelet products.

Evaluation of a new apheresis system for the collection of leukoreduced single-donor platelets

BACKGROUND

The Fresenius COM.TEC cell separator is a new device for producing white cell concentrates (WBCs) and leukoreduced single-donor platelet concentrates (SDPs) and performing therapeutic cytapheresis and plasmapheresis that might replace the Fresenius systems AS104 and AS.TEC 204. This novel system's performance was evaluated for producing leukoreduced SDPs.

STUDY DESIGN AND METHODS

In an investigational phase, each of 200 donors underwent plateletpheresis with the AS.TEC 204 and the COM.TEC systems. The collection efficiency (CE) and WBC contamination of the different techniques were compared. After some hard- and software modifications, the system was evaluated in an additional 800 procedures in the confirmatory phase.

RESULTS

In the investigational phase, the CE of the COM.TEC device was increased significantly in comparison to the AS.TEC 204 device's CE (by 45 +/- 32% when collecting 1 unit of platelets [PLTs] and 1 unit of fresh-frozen plasma and by 43 +/- 42% when collecting only 1 unit of PLTs). Although all AS.TEC products proved to be leukoreduced, 2 percent of the COM.TEC procedures led to PLT concentrates containing more than 1 x 10(6) WBCs. In the confirmatory phase, all 1300 products from 800 COM.TEC procedures proved to be leukoreduced. Furthermore, the CE increased significantly from 53.5 +/- 4.6 percent in the investigational phase to 55.5 +/- 4.9 percent (p < 0.001) in the confirmatory phase.

CONCLUSIONS

These data suggest that the new COM.TEC system offers a significantly and importantly improved CE in plateletpheresis procedures in comparison to the AS.TEC system. In the final version, the PLT products collected with this system fulfill the most stringent criteria for leukoreduced PLTs. This aim was achieved without additional filtration steps and thus without filtration-related PLT loss.

Intrauterine use of hyperconcentrated platelet concentrates collected with Trima Accel in a case of neonatal alloimmune thrombocytopenia

BACKGROUND

Due to the threat of serious or fatal bleedings, fetuses with neonatal alloimmune thrombocytopenia (NAIT) may need intrauterine platelet (PLT) transfusions. To prevent a volume overload or an ABO minor mismatch, standard PLT concentrates need to be washed to increase the PLT concentration and to reduce the plasma content. Hyperconcentrated single-donor PLT concentrates (HCPs) are a therapeutic alternative. The first case of NAIT successfully treated with HCPs collected with the Trima Accel (TA; Gambro BCT) is reported.

CASE REPORT

A 31-year-old woman with a history of NAIT in the preceding pregnancy underwent cordocentesis three times during her third pregnancy (30th, 31st, and 32nd weeks of gestation). NAIT was confirmed by marked fetal thrombocytopenia, a maternal anti-human PLT antigen (HPA)-1a-immunoglobulin G (titer 1:128), and the appropriate HPA genotype of the fetus and the parents. On each cordocentesis procedure, a distinct volume of a HPA-1a-negative HCP with a PLT concentration of 3 x 10(6) PLTs per microL was transfused resulting in high corrected count increments after 2 hours. The HCPs were transfused within 10 hours after collection. One day after the last cordocentesis procedure, a cesarean section was performed. The newborn did not show any bleeding signs, and the PLT count remained on normal levels and no further PLT transfusions were needed.

CONCLUSION

HCPs collected with TA are a useful alternative to washed standard PLT concentrates without the need for further manipulation of the product after collection. Further in vitro and in vivo studies are needed, however, to make definite recommendations for the shelf life of these HCP.

Prospective comparison of high-dose plateletpheresis with the latest apheresis systems on the same donors

BACKGROUND

To improve productivity of automated platelet (PLT) collection, the industry has introduced new instruments or modifications to existing equipment.

STUDY DESIGN AND METHODS

With the same 8 donors for double (DDC) and triple-dose PLT collection (TDC), the Baxter Amicus (AM), the Haemonetics MCS Plus (MCS+), and the Gambro Trima Accel (TA) were evaluated focusing on yield, duration, and citrate donor load. Target endpoints were set at 5.5 x 10(11) to 6.0 x 10(11) PLTs (DDC) and 7.5 x 10(11) to 8.0 x 10(11) PLTs (TDC) in up to 100 and 120 minutes' donation time, respectively.

RESULTS

TA was the most efficient system (74.5 +/- 3.9%) with significant differences from AM (71.1 +/- 3.9%; p = 0.028) and MCS+ (64.0 +/- 7.7%; p = 0.002). TA had advantages over AM for collection rate (10.9 x 10(9) +/- 2.2 x 10(9) vs. 10.1 x 10(9) +/- 1.5 x 10(9) PLTs/min; p = 0.382), whole blood processed (3928 +/- 611 mL vs. 4219 +/- 727 mL; p = 0.382), and time to obtain an established standard dose (TSD 2.5(EU), 30.2 +/- 5.6 vs. 37.7 +/- 5.5 min; TSD 3.5(US), 42.2 +/- 7.8 min vs. 52.7 +/- 7.7 min; p = 0.015), whereas AM was slightly superior in PLT yield (2.81 x 10(11) +/- 0.21 x 10(11) vs. 2.76 x 10(11) +/- 0.31 x 10(11)/unit; p = 0.645). Owing to the lowest draw (42.3 +/- 3.2 mL/min; p < 0.001) and collection rates (6.0 x 10(11) +/- 1.5 x 10(11)/min; p = 0.021), MCS+ was the slowest significantly (p < 0.001) but compensated with fewer citrate reactions owing to lower citrate infusion rates (0.78 +/- 0.11 mL/min/L; p = 0.028).

CONCLUSION

High-dose plateletpheresis was performed efficiently and safely with all three instruments. AM had advantages in PLT yield, and MCS+, in donor comfort. TA was the fastest in obtaining an established standard dose and, because of this advantage, the machine with the highest practical impact in routine use.

Blood component collection by apheresis

Apheresis component collection is a rapidly growing area in the blood collection field. Several instruments with varying capabilities are available. This is a brief review of the equipment available for granulocyte and apheresis component collection and indications for their use. In the United States, granulocytes are collected with the Fenwal CS3000, Fenwal CS3000 Plus, COBE (Gambro) Spectra, Haemonetics LN9000, and Fresenius AS 104. The use of hetastarch for sedimenting agent and stimulation with G-CSF and G-CSF plus dexamethasone have substantially increased granulocyte yields. Plateletapheresis is performed in the United States on the Fenwal CS3000, Fenwal CS3000 Plus, Fenwal Amicus, COBE (Gambro) Spectra, Gambro Trima Version 4, Gambro Trima Accel (Version 5), and Haemonetics LN9000. Automated red blood cell (RBC) collections are performed with the Haemonetics MCS+LN8150, Gambro Trima Version 4, Gambro Trima Accel (Version 5), Amicus, and Baxter Alyx. The RBC can be collected concurrently (with other components) in some instruments or separately in others. Plasma is collected concurrently on several instruments. Plasmapheresis for plasma only is performed on the Fenwal Autopheresis C and Haemonetics PCS2. Granulocyte yields range from 0.46 x 10(10) to 1.0 x 10(10) for unstimulated donors and 2.1 x 10(10) to 2.6 x 10(10) for donors stimulated with dexamethasone or prednisone. The use of G-CSF and G-CSF with dexamethasone has substantially increased granulocyte yields with yields of 4.1 x 10(10) to 10.8 x 10(10) reported. Platelet collection rates of 0.045-0.115 x 10(11) plt/min have been reported. Collection efficiencies of 46-85.7% have been reported. Automated (apheresis) component collection has the advantages of controlled volumes or doses of component, efficient use of the donor, multiple components from the same donor, better inventory control, and better quality control due to less manipulation of the individual components. Disadvantages of automated component collection include the use of expensive equipment and disposables, the need for specially trained machine operators, and lower capacity to collect large volumes of blood compared to whole blood donation. The use of apheresis component collection is rapidly growing to provide the best blood components in the most efficient manner.

Impact of different hold time before addition of platelet additive solution on the in vitro quality of apheresis platelets

BACKGROUND

The quality of platelets (PLTs) stored in PLT additive solution (PAS) is dependent on the type and proportion of the used PAS. No data are available as to whether a different hold time before the addition of PAS to hyperconcentrated PLT suspensions has an impact on PLT quality. The in vitro quality between single-donor PLT concentrates was compared with two different hold times with two PASs.

STUDY DESIGN AND METHODS

On two occasions, 6x10(11) PLTs in 150 mL of plasma were collected from 20 blood donors. The units were split into two equal parts, and 140 mL of PAS-II or PAS-IIIM (randomized sequence) was added after 2 or 8 hours resulting in a PAS proportion of 65 percent. On Days 1, 5, and 7, glucose and lactate concentration, pH value, PLTs' P-selectin expression, response to hypotonic shock, and release of transforming growth factor-beta1 were determined.

RESULTS

On all days, the lactate concentrations were higher and pH values were lower in units with an 8-hour hold time, whereas the results of in vitro tests relating to the in vivo viability and activation of PLTs were similar for both groups. PAS-IIIM-stored PLTs showed a lower glycolytic activity and better results in all performed in vitro tests than PAS-II-stored PLTs.

CONCLUSIONS

Although the metabolism of glucose was enhanced during hold time, the differences between both hold time groups are not meaningful from a biological viewpoint. Therefore, an 8-hour hold time is feasible. PLT storage in PAS-IIIM results in a PLT in vitro quality superior to that of PLTs stored in PAS-II.

Collection of hyperconcentrated platelets with Trima Accel

BACKGROUND AND OBJECTIVES

Lowering the plasma content in single-donor platelet (PLT) concentrates well below 30% implies the need to collect platelets at very high concentrations. Trima Accel (TA) is validated for collection below 4000 x 10(3) PLTs/microl. We evaluated its performance at 5000 x 10(3) PLTs/microl.

MATERIALS AND METHODS

Twenty blood donors underwent apheresis with TA twice collecting either a hyperconcentrated or a standard single-donor platelet concentrate with a target platelet concentration of 5000 or 1200 x 10(3) PLTs/microl, respectively. We analysed the collection efficiency, the collection rate and the quality of the collected by-plasma.

RESULTS

We collected 20 hyperconcentrated and 20 standard units containing 2.56 +/- 0.5 and 3.39 +/- 0.4 x 10(11) PLTs at a concentration of 4518 +/- 978 and 1374 +/- 166 x 10(3) PLTs/microl in 45 +/- 8 and 39 +/- 6 min resulting in a collection efficiency of 47.5 +/- 10.0 and 70.7 +/- 7.9% and a collection rate of 5.9 +/- 1.4 and 8.8 +/- 1.5 x 10(9) PLTs/min, respectively (all results expressed as mean +/- standard deviation). The collected by-plasma showed a very high grade of cell purity and a satisfactory recovery of the clotting factors.

CONCLUSION

Although TA is a suitable device for PLT collection at very high concentrations, improvements are desirable to further increase the productivity above its currently validated upper collect concentration limit.

Washing platelets with new additive solutions: aspects on the in vitro quality after 48 hours of storage

BACKGROUND

Rare clinical conditions cause the need for washed platelet (PLT) concentrates (PCs). Saline-washed PCs can only be stored shortly, however, owing to lack of substrates for PLT metabolism. New PLT additive solutions (PASs) contain such substrates and might be used alternatively. The in vitro quality of apheresis PCs washed with Composol-PS or modified PAS-III (PAS-IIIM) stored up to 48 hours after wash was compared.

STUDY DESIGN AND METHODS

Twelve blood donors underwent two apheresis procedures (A and B) collecting 6.0 x 10(11) PLTs in 500 mL of plasma with a least 2 weeks in between. The PCs collected by Apheresis A were stored for 3 days and then split in two equal units before washing with Composol-PS or PAS-IIIM. The PCs collected by Apheresis B were split after collection. One unit was released for transfusion and 1 unit was stored unwashed up to Day 6 and used as reference unit. In vitro testing was performed before and after washing as well as 24 and 48 hours after wash.

RESULTS

After 48 hours of postwash storage, the units washed with either PAS showed acceptable results for hypotonic shock response (HSR), P-selectin expression, and pH, whereas PLT aggregability was significantly impaired. Throughout the storage, unwashed units showed better in vitro quality. HSR and P-selectin expression were similar before and immediately after the washing procedure.

CONCLUSION

Based on these in vitro results, 48-hour postwash storage of washed PCs with the two PASs seems to be feasible. In vivo recovery studies, however, must confirm this finding in the future.

Hyperconcentrated platelets stored in additive solution: aspects on productivity and in vitro quality

BACKGROUND AND OBJECTIVES

New platelet (PLT) additive solutions (PASs) allow a plasma carryover of < 30% in PLT concentrates. This implicates the need to collect apheresis PLT concentrates at very high PLT concentrations: so-called dry PLTs (DPs). We used the TRIMA, with software version 4 (TRIMA V4), to collect such DPs and investigated the in vitro quality of these PLTs when stored in the new modified PAS-III (PAS-IIIM).

MATERIALS AND METHODS

TRIMA V4 was programmed to collect 6.0 x 10(11) PLTs at a concentration of 5000 x 10(3) PLTs/microl. Two DPs were pooled, split into four equal parts and diluted to obtain secondary pools (SPs) consisting of 70% PAS-III/30% plasma, 70% PAS-IIIM/30% plasma, 80% PAS-IIIM/20% plasma or 100% plasma. In vitro testing was performed on days 0, 1, 5 and 7. Collection efficiency (CE), collection rate (CR) and PLT yield were calculated for each donation.

RESULTS

Thirty-two runs with TRIMA V4 were performed, collecting 6.58 +/- 0.74 x 10(11) PLTs at a concentration of 4255 +/- 914 x 10(3)/microl in 99 +/- 19.9 min, resulting in a CE of 65.3 +/- 8.2% and a CR of 6.92 +/- 1.6 x 10(9) PLTs/min. On day 0, 34-37% of the PLTs in the units prepared for storage were already activated. PLTs stored in 70% or 80% PAS-IIIM showed superior in vitro quality compared to PLTs stored in PAS-III.

CONCLUSIONS

TRIMA V4 is a suitable device for the collection of DPs. Nevertheless, improvements are desirable to further increase the ability to concentrate PLTs at very high levels. The storage of apheresis-derived PLTs in PAS III-M is a very promising approach, even at a plasma carryover of < 30%.

Leukapheresis for the extraction of monocytes and various lymphocyte subpopulations from peripheral blood: product quality and prediction of the yield using different harvest procedures

BACKGROUND AND OBJECTIVES

Leukapheresis of non-mobilized healthy donors is performed to harvest monocytes and lymphocyte subpopulations for use in various therapeutic regimens. In this methodological study, we compared two different leukapheresis programs, using equivalent volumes of processed blood over similar processing periods, to determine the influence of the procedures on the donor peripheral blood count and to establish the procedure that yields the highest quality product.

MATERIALS AND METHODS

The target variables obtained in 41 healthy blood donors who underwent short-term leukapheresis (80-105 min) were retrospectively compared. Twenty-one volunteers were processed on a COBE Spectra machine at the MNC setting and 20 volunteers were processed at the AutoPBSC setting. Data were collected on pre- and postleukapheresis samples and on the product.

RESULTS

AutoPBSC and MNC procedures resulted in a decrease of haemoglobin (5-7%), platelets (17-20%), monocytes (22%) and lymphocytes (23-27%), but not of granulocytes in peripheral blood. Both procedures produced nearly identical leucocyte and lymphocyte yields. AutoPBSC products contained a greater number of granulocytes, monocytes and red cells, but fewer platelets. The preleukapheresis values correlated with the yields for monocytes, T-helper and T-suppressor cells, B-lymphocytes and natural killer cells, but not for granulocytes or platelets.

CONCLUSIONS

Leukapheresis is a safe and efficient procedure for collecting large numbers of peripheral blood monocytes and different lymphocyte populations from non-mobilized donors. The two programs yield comparable leucocyte harvests. Based on our results, yields can be predicted from the peripheral cell counts.

Frequently used plateletpheresis techniques result in variable target yields and platelet recruitment of donors

BACKGROUND

Standard plateletpheresis techniques and effects on platelet (PLT) donors were investigated to provide an informative basis for advancement of apheresis software.

STUDY DESIGN AND METHODS

Three paired groups with 33 male and 22 female blood donors were prospectively investigated by analyzing blood counts of donors and products. Four apheresis platforms, the COBE Spectra LRS and the Trima v4 (Gambro BCT) and the AS.TEC204 and the COM.TEC (Fresenius Hemocare), were compared. Deviations of the collected from programmed PLT targets and donor PLT recruitment were calculated for single-unit PLT concentrates (SU-PCs; 3 x 10(11) PLTs) and double-unit PLT concentrates (DU-PCs; 6 x 10(11) PLTs).

RESULTS

Regarding SU-PCs, the productivity of the COM.TEC machine was superior to the AS.TEC204 machine, because of shorter processing time (54 min vs. 67 min) and higher yields (2.90 x 10(11) PLTs vs. 2.75 x 10(11) PLTs). Compared to the Spectra machine, the Trima v4 machine showed higher collection efficiencies (CEs) and shorter processing time and complied better with the programmed target (SU-PCs, 3.24 x 10(11) PLTs vs. 3.70 x 10(11) PLTs; DU-PCs, 6.87 x 10(11) PLTs vs. 7.56 x 10(11) PLTs). Harvests of the Spectra machine (DU-PCs) exceeded the target by 40 percent, which resulted in high PLT loss for donors. A longer processing time resulted in some higher CEs (SU-PCs, 53%; DU-PCs, 58%), which could contribute to this result. PLT recruitment compensated PLT loss to some extent.

CONCLUSION

The major finding was that the newer devices (COM.TEC and Trima) gave more predictable yields than the older devices (AS.TEC204 and Spectra) and resulted in lower PLT deficit. PLT software should be improved to minimize relevant variations of collected yields regarding the programmed target.

Plateletpheresis does not cause long-standing platelet-derived growth factor release into the donor blood

BACKGROUND

Recently, long-standing elevations of soluble growth factors released from platelets (PLTs) after contact with artificial surfaces during dialysis were described. They could be jointly responsible for the high frequency of death from cardiovascular diseases in dialysis patients. There are no comparable data on the extent and the duration of a growth factor release by plateletpheresis procedures.

STUDY DESIGN AND METHODS

A total of 37 plateletpheresis procedures were performed with two different devices. PLT-derived growth factor (PDGF) isoform AB, transforming growth factor (TGF)-beta1, and beta-thromboglobulin (beta-TG) were measured in the donors' plasma samples, and PLT activation and function were measured by cytometry and aggregometry before and after plateletpheresis and 1 and 24 hours later.

RESULTS

Before apheresis, the following mean plasma levels were found: beta-TG, 98.6 +/- 37.3 IU per mL; PDGF-AB, 71.5 +/- 38.5 pg per mL; and TGF-beta1, 2.24 +/- 0.80 ng per mL. At the end of the apheresis procedures, the mean PDGF-AB level had increased by a factor of 1.8 (p < 0.05). One hour later, the mean PDGF-AB level had normalized again. No significant change in the levels of beta-TG and TGF-beta1 was found by the apheresis procedures. There was no influence of the blood cell separator type on the results.

CONCLUSION

Only a slight and rapidly reversible increase in soluble PDGF-AB was found during plateletpheresis and no increase in soluble TGF-beta1 and beta-TG was found. This change should not be harmful to the donor.

Paired comparison of Gambro Trima Accel versus Baxter Amicus single-needle plateletpheresis

BACKGROUND

Gambro BCT recently introduced the Trima Accel Version 5 (TR) plateletpheresis machine. Platelet (PLT) yields, collection efficiencies (CEs), numbers of white blood cells (WBCs), and processing times of the TR versus the Amicus (Version 2.51) single-needle (AM) procedures were evaluated by use of a prospective paired comparison.

STUDY DESIGN AND METHODS

Target yields of 3.0 x 10(11) to 6.8 x 10(11) PLTs in up to 100 minutes of processing time were used. To detect a difference of 1.0 x 10(11) PLTs with a power of 80 percent, 26 paired comparisons were needed.

RESULTS

The mean amount of whole blood processed was significantly higher for TR than for AM (3795 vs. 3520 mL). The TR and AM were equivalent in regard to mean preprocedure PLT count (259 x 10(9) vs. 251 x 10(9)/L), PLT yields (6.7 x 10(11) vs. 6.5 x 10(11)), split rate (65% vs. 65%), processing time (73 vs. 78 min), and collection rate (0.090 x 10(11) vs. 0.084 x 10(11) PLTs/min). The TR had a significantly lower CE than the AM (76% vs. 86%). All of the products (after splitting) had fewer than 5 x 10(6) WBCs.

CONCLUSIONS

The Trima Accel machine processed significantly more whole blood with equivalent PLT yields, processing time, and number of PLTs per minute compared to the Amicus single-needle procedure, but had a significantly lower CE.

Sample preparation technique and white cell content influence the detectable levels of growth factors in platelet concentrates

BACKGROUND AND OBJECTIVES

Autologous platelet concentrate (PC) is applied locally to improve wound healing and tissue repair. Previous measurements of the growth factor content of platelets have given conflicting results. To date, there is no information on the influence of different preanalytical sample-preparation methods on the detectable amount of growth factors.

MATERIALS AND METHODS

We measured the level of growth factors in PCs obtained by plateletpheresis and by leukapheresis. We subjected aliquots of these components to six different preparation methods: freezing/thawing once or twice; dissolution in 0.5% Triton-X-100; and clot formation by the addition of calcium and thrombin with subsequent incubation for 1 h, for 24 h, or for 1 h followed by freezing and thawing.

RESULTS

In samples dissolved in Triton-X-100, higher levels of growth factors were detected than in the other specimens. In comparison to clot formation, freezing and thawing platelets twice was equivalent with respect to the release of platelet-derived growth factor (PDGF) but superior with respect to the release of transforming growth factor-beta1 (TGF-beta1). Overall, mean levels of 4.77 x 10(-16) g of PDGF-AB, 2.2 x 10(-17) g of PDGF-BB, and 2.41 x 10(-16) g of TGF-beta1 were found per single human platelet in white blood cell (WBC)-poor samples dissolved in Triton-X-100.

CONCLUSIONS

Dissolving PC in Triton-X-100 releases maximum quantities of growth factors from platelets. The release of each growth factor by any sample preparation method should be investigated and interpreted separately. The preanalytical sample-preparation method, as well as the platelet and WBC content, influence the measurable levels of growth factors in PCs. The results implicate the need to correct, considerably upwards, previous estimations of the PDGF content of platelets.

First comparison of productivity and citrate donor load between the Trima version 4 (dual-stage filler) and the Trima Accel (single-stage filler) in the same donors

BACKGROUND AND OBJECTIVES

Aside from new software the blood cell separator TRIMA (GambroBCT) also received a newly designed separation chamber offering a novel single stage separation technology, called Trima Accel. We evaluated this new system focusing on productivity and donor comfort by comparing it to the previous version (Trima version 4) in collecting single-donor platelet concentrates (SD-PCs) and plasma.

MATERIALS AND METHODS

Each of 20 donors underwent platelet apheresis using both devices. We compared the collection efficiency (CE), the collections rate (CR), the volume of the collected plasma and the residual leukocytes. Furthermore we compared donor comfort in terms of duration of the donation, flow of citrate back to the donor and platelet and white blood cell (WBC) loss.

RESULTS

While the number of collected platelets and the platelet concentration did not differ significantly between both techniques the time of the procedure was reduced by 15.6% with Trima Accel. This results in an increase of the CR and CE of 25% and 15% respectively when using Trima Accel. Log normal probability plotting of WBC counts showed that both techniques complied with the European and the US leukoreduction guidelines. The mean flow of ACDA to the donor per minute and per litre blood volume was also reduced by 20%.

CONCLUSION

These data show that the Trima Accel represents a further improvement in apheresis platelet production with a better productivity and donor comfort, especially regarding the mean flow of ACDA to the donor.

In vivo and in vitro comparison of platelets stored in either synthetic media or plasma

Since 1980, several synthetic media have been developed for the storage of platelets for transfusion. At present, platelets suspended in approximately 70% synthetic medium and 30% plasma can be stored for at least 5 days at very stable pH levels, generally pH 6.8-7.2. Present knowledge suggests that synthetic media should contain at least acetate, citrate, phosphate, potassium and magnesium. Future studies will probably result in the inclusion of other components to this list. Glucose for platelet metabolism will generally be supplied by carryover of plasma from the original platelet preparation. In addition, improved plastic containers for the storage of platelets will probably facilitate the introduction of new synthetic media. In six studies comparing synthetic media with plasma as the storage environment, and involving patients with intensive chemotherapy for haematological malignancies, the clinical outcome in terms of corrected count increments (CCI) generally indicated similar results. Three studies suggested significant reduction of the incidence of transfusion reactions of platelets suspended in synthetic media as compared with plasma. For future comparisons of platelet storage in either plasma or new synthetic media, additional platelet survival and recovery studies, as well as patient-transfusion studies, will be needed as in vitro data may not always reflect the clinical outcome. This will add further knowledge to data from the present few clinical studies available that compare storage of platelets in either synthetic media or plasma.

Applying a novel statistical process control model to platelet quality monitoring

BACKGROUND

Many countries are implementing universal WBC reduction of blood components Thus, manufacturing procedures must include QC techniques to detect units that fail to meet established standards.

STUDY DESIGN AND METHODS

A statistical process control model, based on the exponentially weighted moving average of the cumulative distribution function (CDF-EWMA), was developed to detect shifts in a mean and/or variance of a process. The model's parameters (weights) were optimized to maximize detection of an out-of-control process while minimizing sensitivity to autocorrelation. Validation was performed using a retrospective set of WBC-reduction data obtained from a blood bank. The WBC-reduction process was considered in control when there was 95-percent confidence that more than 95 percent of platelet concentrates would contain less than 1 x 10(6) WBCs (6.0 log WBC) as required by European standards. A sentry setting of 5.7 log WBCs was used to allow earlier detection of an out-of-control process.

RESULTS

Graphic output of the CDF-EWMA model provided a continuous update of the probability that a WBC-reduction process was in control. Using the validation data, the model showed that the process was in control until Observation 332, at which point residual WBCs per unit increased. However, the first platelet concentrate to exceed specified criteria (Observation 346) occurred after the model detected that the process was out of control, demonstrating the forecasting value of this model. This deviation corresponded to an equipment failure in a single apheresis instrument. The Shewhart and EWMA techniques were similarly able to detect when the process was out of control using the test data.

CONCLUSION

As a statistical process control model, the CDF-EWMA provides real-time estimation of the fraction of components meeting a regulatory limit. It is capable of detecting developing QC problems before units fail to meet regulatory requirements and is a potential alternative to other QC techniques for monitoring WBC reduction of blood components.

Volunteer donor apheresis

Volunteer donor apheresis has evolved from early plasmapheresis procedures that collected single components into technically advanced multicomponent procedures that can produce combinations of red blood cells, platelets, and plasma units. Blood collection and utilization is increasing annually in the United States. The number of apheresis procedures is also increasing such that single donor platelet transfusions now exceed platelet concentrates from random donors. Donor qualifications for apheresis vary from those of whole blood. Depending on the procedure, the donor weight, donation interval, and platelet count must be taken into consideration. Adverse effects of apheresis are well known and fortunately occur in only a very small percentage of donors. The recruitment of volunteer donors is one of the most challenging aspects of a successful apheresis program. As multicomponent apheresis becomes more commonplace, it is important for collection centers to analyze the best methods to recruit and collect donors.

Preparation of FFP as a by-product of plateletpheresis

BACKGROUND

To reduce the production costs of single-donor platelets (SDPs), a study was conducted to investigate whether plasma collected as a by-product of plateletpheresis satisfies the quality requirements for FFP without impairing the quality of the SDP component.

STUDY DESIGN AND METHODS

Ninety-two donors with platelet (PLT) counts <270 x 10(9) per L underwent plateletpheresis using an automated cell separator (Spectra Apheresis System with the Leukoreduction System [LRS], Gambro BCT, Lakewood, CO). The machine was programmed to collect 3 x 10(11) PLTs in 250 mL of plasma with an additional unit of 350 mL of plasma or 3 x 10(11) PLTs in 250 mL of plasma without additional plasma in 10 procedures. FV and FVIII and residual RBCs, WBCs, and PLTs in the plasma were measured for quality control.

RESULTS

FV was 0.87 +/- 0.18 IU per mL, and FVIII was 1.32 +/- 0.48 IU per mL in the plasma components (n = 41). The recovery was 94.1 +/- 5.5 percent for FV and 102.2 +/- 9.5 percent for FVIII when compared with the donors' predonation values. Residual cells were 0.002 +/- 0.009 x 10(9) RBCs per L (n = 30), 12 +/- 6 x 10(9) PLTs per L (n = 30), and 0.32 +/- 0.37 x 10(6) WBCs per L (n = 92).

CONCLUSIONS

Using the automated cell separator and special software, it is possible to collect plasma as a by-product of plateletpheresis that meets the properties requested for FFP without impairing the quality of the SDP components. The content of clotting factors is within the requested range for FFP. Residual cell counts are within all European and U.S. specifications for FFP, and the WBC content even satisfies the criteria for WBC-reduced blood components. The collection of FFP as a by-product does not cause any additional costs and thus helps to reduce the costs in preparing blood components.

Different preparation methods to obtain platelet components as a source of growth factors for local application

BACKGROUND

Autologous platelet components were recently used as part of tissue-engineering strategies in oral and maxillofacial surgery. Various preparation methods were investigated to define standardized blood bank components and to collect data on the growth factor content of human platelets before and after storage.

STUDY DESIGN AND METHODS

Apheresis platelets (AP), buffy coat-derived platelets (BCP), platelets prepared by tube method (TP), and highly concentrated samples prepared from AP and from BCP were evaluated for standard quality criteria of platelet components and for their concentration of transforming growth factor (TGF)-ss1, platelet-derived growth factor (PDGF)-AB, and PDGF-BB. AP were stored for 5 days. On Days 3 and 5, these components and freshly prepared, highly concentrated samples were evaluated for the same measures.

RESULTS

Platelet concentration in TP was lower than that in the other groups (p<0.05). However, the concentrations of PDGF-AB, PDGF-BB, and TGF-ss1 were comparable in the three groups. TP showed higher spontaneous CD62 expression than did AP and BCP. The three preparation procedures resulted in significantly different WBC contamination, with the highest levels in TP. For the whole series of measurements, there was a strong correlation between growth factor levels and platelet concentration (p<0.05), which was due to the face that the growth factor content of concentrated platelet samples was tenfold that of AP, BCP, and TP. In TP, the WBC concentration was correlated with PDGF levels (p<0.05). After 5-day storage, the mean levels of PDGF-AB, PDGF-BB, and TGF-ss1 were 57.1, 43.0, and 72.0 percent of the initial values in AP. Overall, multiple regression analysis revealed the following factors influencing the measured growth factor concentrations: platelet concentration, baseline CD62 expression, lactate production, and WBC contamination.

CONCLUSION

Various methods enable the preparation of platelet components and of highly concentrated components for local use according to standard blood banking criteria. The obtained components differ, particularly in their WBC content and in vitro platelet activation. These findings are relevant for planning and evaluating further studies of locally usable autologous platelet components.

Thrombopoietin therapy increases platelet yields in healthy platelet donors

The recombinant thrombopoietins have been shown to be effective stimulators of platelet production in cancer patients. It was therefore of interest to determine if one of these, pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF), could be used to increase platelet counts and consequently platelet yields from apheresis in healthy platelet donors. In a blinded, 2-cycle, crossover study, 59 platelet donors were randomized to receive a single subcutaneous injection of PEG-rHuMGDF (1 microg/kg or 3 microg/kg) or placebo and 15 days later undergo platelet apheresis. Donors treated with placebo had a median peak platelet count after PEG-rHuMGDF injection of 248 x 10(9)/L compared with 366 x 10(9)/L in donors treated with 1 microg/kg PEG-rHuMGDF and 602 x 10(9)/L in donors treated with 3 microg/kg PEG-rHuMGDF. The median maximum percentage that platelet counts increased from baseline was 10% in donors who received placebo compared with 70% in donors who received 1 microg/kg and 167% in donors who received 3 microg/kg PEG-rHuMGDF. There was a direct relationship between the platelet yield and the preapheresis platelet count: Placebo-treated donors provided 3.8 x 10(11) (range 1.3 x 10(11)-7.9 x 10(11)) platelets compared with 5.6 x 10(11) (range 2.6 x 10(11)-12.5 x 10(11)) or 11.0 x 10(11) (range 7.1 x 10(11)-18.3 x 10(11)) in donors treated with 1 microg/kg or 3 microg/kg PEG-rHuMGDF, respectively. Substandard collections (<3 x 10(11) platelets) were obtained from 26%, 4%, and 0% of the placebo, 1 microg/kg, and 3 microg/kg donors, respectively. No serious adverse events were reported; nor were there events that met the criteria for dose-limiting toxicity. Thrombopoietin therapy can increase platelet counts in healthy donors to provide a median 3-fold more apheresis platelets compared with untreated donors.

Revisitation of the clinical indications for the transfusion of platelet concentrates

Platelet transfusion is indicated when the expected benefits of increasing the number of functional platelets in the patient's circulation outweigh the potential risks generated by exposing the patient to allogeneic, manipulated and stored blood products such as platelet concentrates. Although reassuring evidence has been collected indicating that current risks associated with blood transfusion are lower than those of several voluntary and involuntary human activities, balancing benefits and risks of platelet transfusion may not be easy in a proportion of patients and in a number of conditions. To facilitate this task, guidelines have been developed, with particular attention to cancer patients. As witnessed by the most recent guidelines, over the last few years there has been a progressive, although not absolute, consensus on: (i) the routine use of platelets as a tool to prevent hemorrhage in oncohematology (the so called 'prophylactic approach') as opposed to limiting platelet transfusion to actual bleeding episodes (the so-called 'therapeutic approach') and (ii) lowering the trigger for prophylactic platelet transfusion in stable oncohematology recipients from 20 x 109 to 10 x 109 platelets/L. This has been accompanied by a reduction of platelet use per oncohematology patient of about 20%, an important outcome in view of the progressive increase of platelet demand due to more aggressive therapy in cancer patients. In selected clinical conditions, specific triggers ranging from 30 x 10(9) to 100 x 10(9) platelets/L have been recommended, with higher values when surgical procedures are required for the patient's treatment. Indications and trigger values proposed in the guidelines must be considered within the context of careful clinical evaluation of each patient, with a clear appreciation of the power of discrimination of automated platelet counters at low counts, and of the quality and local availability of platelet products for emergency.

Paired comparison of apheresis platelet function after storage in two containers

Platelet quality after storage strongly depends on the pre-storage quality as well as on the storage conditions determined by the storage container. In this paired study, we evaluated two different containers (MedSep CLX and Delmed DPL-110). The Fresenius AS104 cell separator was used to prepare 17 platelet concentrates that were split and distributed into the containers to be compared. Cell counts, blood gas analysis, morphological scores, glucose and lactate levels, platelet activation, and platelet aggregation were measured before splitting at the day of preparation and after storage at day 3 and day 5. At day 3, there was no significant difference between the two bags apart from increased lactate and decreased pCO(2) concentrations in the CLX bags. At day 5 there were significantly higher lactate concentrations, pO(2) levels, and aggregation after stimulation in the CLX group, while the glucose and pCO(2) concentrations were significantly lower in these platelet concentrates as compared to the DPL-110 group. However, these parameters did not influence the functional parameters tested. While the platelet quality decreased during storage in all bags, the functional changes were nearly identical in both bags tested. We conclude that both bags are equivalent for 5-day storage of platelet concentrates.

Comparison of a new WBC-reduction system and the standard plateletpheresis protocol in the same donors

BACKGROUND

A cell separator (Spectra, Gambro BCT) with an integrated leukoreduction system (LRS) for producing WBC-reduced single-donor platelet concentrates has been shown to result in a slightly reduced collection efficiency as compared to the former Spectra system without LRS. A novel modified system for improved collection efficiencies (LRS Turbo, Gambro BCT) was evaluated.

STUDY DESIGN AND METHODS

Each of 37 donors underwent plateletpheresis using the LRS Turbo (LRS-T) and the standard LRS (LRS) of the Spectra cell separator. The collection efficiency and WBC contamination of the different techniques were compared. Platelets were counted automatically and WBCs were counted by using one or two full grids of a Nageotte chamber.

RESULTS

The preseparation and postseparation numbers of RBCs, WBCs, and platelets, as well as the number of collected platelets, did not differ for the two techniques. In the LRS-T separations, the collection efficiency was 112 percent of that in the LRS procedures. Median residual WBCs in the platelet components were 0.0256 x 10(6) per LRS-T procedure and 0.0253 x 10(6) per LRS procedure. The purity of the LRS-T components was not less than that of the standard LRS components, whereas the collection efficiency of the LRS-T was significantly greater, 44.9 percent versus 40.7 percent.

CONCLUSIONS

The LRS-T procedures produced platelet concentrates with WBC-reduction capacity that is comparable to that obtained with the standard LRS procedures, which have previously been described as satisfying the most stringent criteria for WBC-reduced platelets. The new technique significantly improved the collection efficiency of the plateletpheresis procedure.

Effect of gamma radiation on the in vitro aggregability of WBC-reduced apheresis platelets

BACKGROUND

The effect of gamma radiation on single-donor apheresis platelet concentrates (SDPs) has been elucidated only incompletely. The only existing report on the function of SDPs stored in the irradiated state found a deterioration in the in vitro aggregability at the end of shelf life in SDPs divided before irradiation with 1500 cGy.

STUDY DESIGN AND METHODS

The in vitro properties of platelets were examined in four series of irradiated and control platelets, each obtained from the same 15 donors. Irradiation with 3000 cGy was performed on Days 0, 3, and 5. Cellular content, aggregability by ADP alone or ADP and epinephrine, spontaneous and induced CD62 expression, beta-thromboglobulin release, glucose consumption, lactate production, and pH were measured immediately after preparation and on Days 3 and 5 after donation.

RESULTS

Comparable in vitro properties were measured in irradiated and control platelets, whether irradiation was performed on Day 3 or Day 5. However, in platelets irradiated on Day 0, we found a significantly better in vitro aggregability by 20 microM: ADP immediately after irradiation and by 10 microM: ADP and 2 microM: epinephrine at the end of shelf life than was found in the other groups (Day 5 results: Day 0 irradiation: 75 +/- 32%; Day 3 irradiation: 45 +/- 45%; Day 5 irradiation: 47 +/- 41%; control: 40 +/- 24%; p<0.05).

CONCLUSION

Gamma radiation had no adverse effect on platelet quality in extremely WBC-reduced SDPs. On the contrary, a slight, but significantly better in vitro aggregability was found in SDPs irradiated before storage than in platelets irradiated later during storage and in unirradiated platelets. This increased in vitro aggregability persisted until the end of shelf life.

Comparison of plateletpheresis concentrates produced with Spectra LRS version 5.1 and LRS Turbo version 7.0 cell separators

BACKGROUND

The importance of transfusing WBC-reduced blood components is widely recognized, as it reduces the risk of alloimmunization and transfusion-transmitted CMV infections. The latest generation of cell separators allows the collection of WBC-reduced apheresis platelet concentrates (APCs).

MATERIALS AND METHODS

Consecutive APCs (n = 232) were retrospectively evaluated: 163 collected with the Spectra LRS [leukocyte-reduction system] Version 5.1 (Group A) and 69 with the LRS Turbo Version 7.0 (Group B) (both: COBE BCT). Donor peripheral blood count, procedure data, platelet yield, collection efficiency (CE), and residual WBC count in APCs were recorded.

RESULTS

The platelet yield was higher in Group B than in Group A: 5.5 +/- 1.4 versus 4.4 +/- 1.1, p<0.0001; residual WBCs were <5 x 10(6) in 99.4 percent of Group A APCs and in 97.1 percent of Group B APCs. CE was higher in Group B than in Group A: 51.4 +/- 8.7 versus 43.6 +/- 6.3, p<0.0001. Moreover, a correlation between predonation platelet count and platelet yield was observed in both groups. A double product (platelet yield >6.0 x 10(11)) was obtained in 28.9 percent of Group B APCs and in 9.2 percent of Group A APCs.

CONCLUSIONS

The Spectra LRS Turbo version 7.0 release showed a better CE and resulted in a higher platelet harvest than did the LRS version 5.1. High predonation platelet counts allow a higher platelet yield.

Quality evaluation of plateletpheresis using the new AMICUS (Baxter) cell separator: evolution of CD 62 expression

The purpose of this study was to evaluate the new AMICUS (Baxter-Fenwal Division) cell separator in terms of donor safety, efficiency, and quality of the product obtained. One hundred eighty-three single-donor plateletpheresis procedures were performed, using a collection of 4-4.5 x 10(11) platelets as endpoint. During the first part of the study, the mean volume processed was 3,225 ml and the mean procedure duration 69.5 min. During the second part, after a software change, the mean volume and mean procedure time were 3,071 ml and 68.3 min, respectively. According to local policy, every collection bag was separated into two therapeutic units each containing a mean of 1.87 (1.83) x 10(11) platelets. The white blood cell (WBC) contamination per therapeutic unit was less than 5 x 10(6) in 91% of phereses performed in part one of the study and in 98% of phereses performed in part two. During the recommended 5 days storage, sequential in vitro analyses were performed in 27 units, showing limited platelet activation according to CD62 expression and morphological changes on electron microscopy (EM). Furthermore, there was a correlation between CD62 expression and the degree of WBC contamination (P = 0.03). In conclusion, platelet collection with the new Amicus allows for high platelet yields of adequate quality as judged by WBC content, CD62 expression, and electron microscopic morphological changes.

Periodic alternating interface positioning to lower WBC contamination of apheresis platelet concentrates: a multicenter evaluation

BACKGROUND

A new software version of a cell separator (AS TEC 204, Fresenius) providing WBC-reduced single-donor plateletpheresis concentrates was tested.

STUDY DESIGN AND METHODS

Dual-needle apheresis procedures (n = 621) were performed in three centers, using either fixed interface positioning (FIP) or periodic alternating interface positioning (PAIP). The other separation parameters (e.g., anticoagulant:whole-blood ratio, and blood flow) were set individually. All platelet concentrates were evaluated for platelet yields and contaminating WBCs.

RESULTS

The introduction of the PAIP resulted in a significant (p<0.001) reduction in contaminating WBCs (median, 30,000) from the numbers seen with FIP (median, 2,300,000) while maintaining the separation efficacy (47%) and separation time. Ninety-eight percent of all concentrates contained less than 5 x 10(6) WBCs per concentrate and 92 percent contained less than 1 x 10(6).

CONCLUSION

Plateletpheresis using the AS TEC 204 cell separator with PAIP is a valid alternative to WBC reduction by filtration. It may provide WBC-reduced platelet concentrates without the additional cost of filters. However, the reliability of the WBC reduction is not yet advanced enough that PAIP can be employed without any monitoring of the end product.

Prospective comparison of plateletapheresis using four apheresis systems on the same donors

To address the demand for higher plateletapheresis efficiency while maintaining consistent leukoreduction, manufacturers of apheresis systems have introduced new equipment or modifications to existing equipment. Using the same 20 donors, we compared the Fresenius AS104 (AS104), Fenwal Amicus, and COBE Spectra Version 7 Leukoreduction System (Turbo) to the COBE Spectra Version 5 Leukoreduction System (V5-LRS) and each other in regard to platelet (plt) collection efficiencies, processing times, and leukoreduction consistency. Using current pre-procedure platelet counts, target endpoints were set at 6-6.5 x 10(11) plt or 3.3-4.0 x 10(11) plt in up to 100 minutes processing time. Median platelet yields for V5-LRS, AS104, Amicus, and Turbo were 3.98, 3.63, 5.03, and 4.99 x 10(11) plt respectively; median collection efficiencies were 53, 46, 73, and 56% respectively; median collection rates were.049,.039,.065, and. 060 x 10(11) plt/minute respectively; double product frequencies were 35, 10, 40, and 30% respectively; and median processing times were 87, 92, 77, and 79 minutes, respectively. Amicus had a significantly higher collection efficiency and higher incidence of double products than all other systems. While AS104 had a significantly lower collection efficiency and lowest double product frequency than all other systems, Amicus and Turbo had significantly lower processing times than V5-LRS and AS104. AS104 leukoreduction was inconsistent, but V5-LRS, Amicus, and Turbo were consistently leukoreduced ((99.8% had <5 x 10(6) WBC at 95% confidence interval). The best overall performance was for the Amicus with Turbo a close second.

Cost effectiveness of quality assurance in plateletpheresis

BACKGROUND AND OBJECTIVES

A quality assurance system (QAS) is part of modern blood banking facilities. Quality control of single donor platelet (SDP) concentrates includes the determination of the platelet (PLT) yield and the white blood cell (WBC) contamination. Improvements in modern apheresis technology allow the collection of high PLT yields and leukoreduced products. Double dose SDPs can be split and WBC-reduced products may be labelled as leukodepleted thereby reducing costs.

MATERIAL AND METHODS

3309 SDPs obtained with the Amicus, AS 104, AS.TEC 204 and MCS + blood cell separators were retrospectively analysed for their PLT yield. SDPs with > or = 4.0 x 10(11) PLTs were considered as double dose SDPs and split. WBCs were determined microscopically in 170 SDPs. SDPs with a leukocyte content < 1.0 x 10(6) were labelled as leukodepleted and no further WBC filtration was recommended.

RESULTS

PLT yield was statistically higher in SDPs from the Amicus device, 84.8% of these products could be split. Double dose concentrates were collected in 22.7% with the MCS + machine and in 4.8% with the AS 104/AS.TEC 204 blood cell separators. The savings for disposables was $150,041 and for infectious disease testing $75,766. After the subtraction of the costs for PLT determinations in all SDPs $215,880 could be saved. WBC contamination was statistically lowest in in-line filtered SDPs from the MCS + device (median 0.29 x 10(5), range 0.22-9.96 x 10(5)) and all of these products were considered as fulfilling the criterion of leukodepeletion so that we were able to save $17,135 for bedside filters. Median WBC content was 0.75 x 10(5) (range 0.35-22.5 x 10(5)) in SDPs from the Amicus and 0.9 x 10(5) (range 0.27-99.8 x 10(5)) in SDPs from the AS 104/AS.TEC 204 devices, respectively.

CONCLUSION

Blood cell separators of the newest generation allow the collection of leukodepleted double dose SDPs. An intensified QAS in plateletpheresis allows the decision whether a product can be split and/or released as leukodepleted. By this means we were able to save a total of $233,015 per year.

Plateletpheresis efficiency: a comparison of the spectra LRS and AMICUS separators

BACKGROUND

Optimizing the yields of plateletpheresis by increasing collection efficiencies may provide several benefits: to patients, by increasing the dose in single-donor platelet (SDP) units; to the collection center, by increasing the percentage of components that may be split into double units; and/or to the donor, by reducing the duration of donation.

STUDY DESIGN AND METHODS

A prospective, randomized study was undertaken to compare the efficiency of platelet collection in paired donations by 21 donors on two cell separators (Spectra LRS, version [v] 5.1; and AMICUS, v2.37). The order of donation was randomly assigned; donations were performed at least 2 weeks apart. A fixed blood volume (4000 mL) was processed by utilizing standard protocols. Findings were confirmed in a retrospective, matched study that compared the two separators by using fixed collection times (90 min).

RESULTS

The AMICUS and Spectra LRS separators consistently produced white cell-reduced (<1 x 10(6) white cells) components. The AMICUS harvested 32 percent more platelets on average (median, 4.9 x 10(11); range, 1.5-8.7 x 10(11)) than the Spectra LRS (median, 3.7 x 10(11); range, 2.1-7.7 x 10(11)) (p = 0.03), with mean times of 71.5 and 66.0 minutes (p = 0.03), respectively, to process 4000 mL. Mild donor reactions tended to be more common on the AMICUS separator, which used significantly more ACD (median 482 mL vs. 389 mL; p<0.0001) than on the Spectra LRS.

CONCLUSIONS

The AMICUS separator harvested more platelets per unit of blood volume processed than the Spectra LRS. Possible benefits include increased dose in each single-donor unit, increased double-unit harvests, and/or shorter donation time.

The influence of automated plateletpheresis on systemic levels of hematopoietic growth factors

BACKGROUND

Megakaryocytopoiesis and platelet production are regulated by several hematopoietic growth factors. The present study focuses on the effects of automated plateletpheresis on systemic levels of different hematopoietic growth factors.

STUDY DESIGN AND METHODS

Platelet count, mean platelet volume, and serum levels of thrombopoietin, erythropoietin, interleukin-1beta, interleukin-6, and stem cell factor in 21 healthy donors were measured before platelet collection, after the first half of the apheresis procedure, at the end of apheresis, and on Days 1, 2, and 7 thereafter.

RESULTS

Thrombopoietin levels (initial level: 49.5 +/- 25.5 pg/mL) showed a significant increase between measurements taken at the end of apheresis and Day 1 (56.9 +/- 26.7 pg/mL; p = 0.01). There was a highly significant decrease in stem cell factor levels during apheresis (p<0.0005), reaching preapheresis values (1679 +/- 210 pg/mL) on Day 1. A highly significant increase in erythropoietin levels (initial level: 7.5 +/- 4.0 U/L) was seen after apheresis (p<0.0005 on Days 1 and 2). The level remained significantly elevated until Day 7 (p = 0.004). Interleukin-1beta and interleukin-6 levels (before donation: 1.4 +/- 1.8 pg/mL and 1.1 +/- 0.7 pg/mL, respectively) did not change during the observation period. Thrombopoietin levels correlated consistently and inversely with stem cell factor levels after apheresis (Day 1, r = -0.46, p = 0.035; Day 2, r = -0.50, p = 0.02; Day 7, r = -0.50, p = 0.02).

CONCLUSION

The data show a coordinated response of the hematopoietic system to platelet loss. It is suggested that the decrease in serum stem cell factor levels during apheresis reflects the consumption of stem cell factor by early hematopoietic progenitors that expand to initiate early megakaryocytopoiesis. The temporary increase in thrombopoietin is the result of platelet loss and serves as a stimulus for subsequent thrombopoiesis. The pronounced elevation of erythropoietin after apheresis suggests a role for this primarily erythropoietic cytokine in thrombopoiesis, too.

Antibodies to private and public HLA class I epitopes in platelet recipients

BACKGROUND

Transfusions or pregnancies can cause immunization against private HLA determinants and public epitopes shared by more than one private HLA antigen. HLA antibodies are correlated with febrile transfusion reactions, lower platelet response following platelet transfusion, and an increased rate of renal transplant rejection. Until now, antibody specificities in alloantisera from platelet recipients have been poorly characterized.

STUDY DESIGN AND METHODS

Consecutive serum screens from platelet recipients were analyzed for antibodies against private HLA class I antigens and public HLA epitopes using a serum analysis program based on the 2 x 2 table analysis of correlations. Serum screens of highly immunized patients and of patients with new alloimmunization events were reviewed separately.

RESULTS

Of the serum screens from 566 platelet recipients, 1577 indicated alloimmunization (panel-reactive antibodies >5%). The program assigned a specificity in 1024 of these screens (64.9%) and at least once in 522 of 566 patients (92.2%). In 267 patients, antibodies detecting public epitopes in the combined A- or B-locus cross-reacting groups were found; other public markers were detected in 39 patients. Patterns of reactivity were remarkably less stable than in patient groups previously studied. In many patients, antibodies with apparent private epitope specificity preceded the identification of antibodies against a shared marker of the same cross-reactive group. However, the disappearance of antibodies (whether or not this was followed by a new antibody against a private or public marker belonging to another cross-reacting group) was also observed.

CONCLUSION

The computerized analysis of microlymphocytotoxicity tests enhances the rate of antibody specification in sera from platelet recipients with lymphocytotoxic antibodies. The identified antibodies should be taken into account in the selection of platelet donors. The data confirm and extend previous observations on HLA class I antibodies and elucidate new alloimmunization events.

White cell reduction during plateletpheresis: a comparison of three blood cell separators

BACKGROUND

White cell (WBC)-reduced single-donor platelet concentrates (SDPs) can be collected by the newest generation of blood cell separators. Three WBC-reduction techniques during plateletpheresis were investigated in the present study with respect to WBC content and platelet yield.

STUDY DESIGN AND METHODS

The Amicus device used the elutriation principle for WBC reduction, and separations with periodically alternating interface position (PAIP) were employed in the AS.TEC 204. WBC reduction by in-line filtration was performed in the MCS+. Platelets were measured electronically and WBCs were determined manually (Nageotte chamber).

RESULTS

In-line filtered SDPs showed significantly lower WBC content (0.088+/-0.178 x 10(6)) than SDPs that were WBC reduced by elutriation (0.31+/-0.48 x 106) or PAIP technique (0.89+/-1.57 x 10(6), p = 0.0001). Platelet yield (5.0+/-0.46 x 10(11)) was significantly higher in components obtained with the Amicus device (p = 0.0001). The AS.TEC 204 and MCS+ gave similar results for platelet yields: 3.15+/-0.63 and 3.28+/-0.71 x 10(11), respectively.

CONCLUSIONS

The plateletpheresis systems studied allow the collection of WBC-reduced SDPs. In-line filtration resulted in the best WBC reduction. Some SDPs collected with the devices studied had a WBC content >1 x 10(6) per unit. Platelet yield was significantly higher in SDPs from the Amicus device.

In vitro and in vivo properties of various types of platelets

The most popular procedures used to prepare platelet concentrates (PC) can be categorized into methods using platelet rich plasma (PRP) obtained by soft centrifugation of whole blood units, methods using buffy coats (BC) obtained by hard centrifugation of whole blood units, and apheresis procedures. The main feature that differentiates apheresis PC from whole blood unit derived PC is that apheresis reduces the number of donors necessary to support a recipient, although the advantages related to this feature have not been conclusively documented. From the biochemical point of view, a limited number of comparative studies and a large series of non-comparative studies indicate that differences in PC obtained with different protocols depend more on the performances of the production laboratory rather than the preparative approach--PRP, BC or apheresis--itself. Similarly, the clinical effectiveness of PC seems to depend more on PC age, storage modalities and recipient's conditions rather than primarily on the method of PC preparation. Despite the basic differences in the three preparative approaches, all methods share a number of key elements that are necessary pre-requisites for a successful platelet transfusion therapy: minimization of the risk of bacterial contamination by careful donor skin disinfection and temperature control during PC production and storage; protection of aerobic metabolism during PC storage; laboratory quality control including at least pH and volume determinations, platelet and white cell counts and visual inspection of the swirling phenomenon at time of release. Future directions in the field of PC production include the development of new products such as infusible platelet membranes, thrombospheres, thromboerythrocytes and reconstituted freeze-dried platelets.