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Background: A comparative study evaluated the retention of apheresis platelet (A-PLT) in vitro properties prepared with PLT additive solution (PAS)-III or 100% plasma and stored with continuous agitation (CA) and without continuous agitation (WCA)., Study Design and Methods: PLTs collected with the Amicus cell separator (Fenwal, Inc.) were utilized to prepare two matched components, each with approximately 4 × 10(11) PLTs. In the primary study, one component contained 65% PAS-III/35% plasma and the other 100% plasma. Four storage scenarios were used, one with CA and three with periods without agitation under simulated shipping conditions. In vitro assays were used early and after 5 days of storage., Results: pH levels after 5 days with CA were less with PAS-III components than 100% plasma components, with levels always above 6.6 in any component. With CA, a number of other variables were reduced even early during storage with PAS-III including morphology, extent of shape change, hypotonic stress response, adhesion, and aggregation. Storage WCA resulted in only a limited increase in the magnitude of the assay differences between PAS-III and 100% plasma components. Periods WCA did not reduce the pH below 6.6. The thromboelastograph variable associated with the strengthening of clots by PLTs was essentially comparable with PAS-III and plasma components throughout storage with CA or WCA., Conclusion: The data indicate that a 100% plasma medium provides for better retention of specific in vitro PLT properties, with CA and WCA, although the clinical significance of these in vitro decrements due to PAS-III is unknown., (© 2011 American Association of Blood Banks.)

Background: To facilitate volume control in neonates, platelets (PLTs) are aliquoted and stored for short periods in non-gas-permeable syringes before infusion. Although agitation of PLTs during storage in gas-permeable bags is performed to maintain their quality, the effect of syringe agitation during storage is unknown., Study Design and Methods: Double apheresis PLTs (n = 6) were collected and split, providing two identical products. On Days 2 and 4 of storage, aliquots from one bag of each pair were transferred to two syringes and stored for 6 hours on flatbed agitator or were left at 20 to 24 °C without agitation. A series of in vitro tests was performed on Days 0, 2 (Hours 0 and 6), and 4 (Hours 0 and 6). Control samples were obtained from the second matched bag that was stored on the agitator. Data were analyzed by one-way analysis of variance with differences considered significant if the p value was less than 0.05., Results: Comparable results for several PLT variables were obtained with or without agitation of the syringes. On Day 4 Hour 6, pH values were 7.18 ± 0.12 (agitated syringes) and 7.19 ± 0.1 (nonagitated syringes), and extent of shape change and hypotonic shock response measurements were not significantly different between agitated syringes and nonagitated syringes (23.7 ± 6.4 and 74.3 ± 9.8% vs. 23.3 ± 5.4 and 76.0 ± 7.6%), respectively., Conclusion: Based on in vitro testing, apheresis PLT aliquots can be stored in syringes for at least 6 hours without agitation before transfusions., (© 2011 American Association of Blood Banks.)

Background: pH measurements of platelet (PLT) components remain a key parameter when assessing how storage and shipping conditions influence the retention of PLT properties. Studies were conducted to characterize variations in pH measured with two pH meters and a blood gas analyzer., Study Design and Methods: Samples were obtained from apheresis PLT units that were stored with or without continuous agitation to measure a range of pH values. pH values were determined with pH meters at room temperature (20-24°C) upon placing of samples in 5-mL sterile polypropylene tubes and with the blood gas analyzer at 37°C upon injection of identical samples, with conversion to 22°C., Results: The calculated coefficient of variation (%CV) of pH measurements using pH meters (n = 10) was 0.43% or less. The %CV values were comparable with different samples having pH values ranging from 6.0 to 7.4. The %CV levels with the blood gas analyzer were comparable to those observed with the pH meters. The difference in the mean pH values for the two pH meters was no greater than 0.10 units, with 9 of 10 samples having differences in values of 0.05 or less; however, greater differences of values (0.1 to 0.2) were observed between pH measured using the blood gas analyzer and pH meters., Conclusion: Our data show good precision and comparability of pH measurements with two pH meters. Differences in pH values were greater on comparison of the blood gas analyzer with the pH meters., (© 2011 American Association of Blood Banks.)

Background: Apheresis platelet (PLT) units are not routinely agitated during transit. Our study compared the in vitro properties of apheresis PLT units that were stored with continuous agitation (CA) and without continuous agitation (WCA) during two separate periods, immediately after collection and between Day 2 and Day 3 of storage., Study Design and Methods: Two identical apheresis PLTs units were prepared from collections with Amicus (n = 11, Fenwal, Inc.) and Trima (n = 10, CaridianBCT) cell separators. One apheresis PLT unit was continuously agitated, starting routinely within 30 minutes of collection, and an identical apheresis PLT unit was held without agitation initially for 7 to 8 hours and subsequently for 24 hours between Day 2 and Day 3 of storage. The apheresis PLT units were maintained WCA at 20 to 24 °C in a shipping box. In vitro PLT properties were evaluated on Day 1 (day after collection), after 5 and 7 days of storage., Results: With both Amicus and Trima apheresis PLT units, the mean PLT content and concentration of CA and WCA were comparable and essentially constant throughout storage. Mean pH levels (± 1 SD) after 5 days for Amicus apheresis PLT units were 6.97 ± 0.20 (WCA) and 7.13 ± 0.16 (p < 0.001, CA) and for Trima apheresis PLT units 6.97 ± 0.21 (WCA) and 7.22 ± 0.17 (p < 0.001, CA). In vitro variables, including percentage of disc PLTs, extent of shape change, and hypotonic stress levels, after 5 days of storage, showed mean differences between WCA and CA that were less than 15%., Conclusion: The in vitro results show that apheresis PLT units can be stored without agitation for 7 to 8 hours immediately after collection and also subsequently during storage for 24 hours with minimal influence on in vitro PLT properties compared to continuously agitated PLTs., (© 2010 American Association of Blood Banks.)

Background: Efforts to minimize white blood cell alloantibodies, responsible for transfusion-related acute lung injury (TRALI) in components with high-volume single-donor plasma include consideration of plateletpheresis donor screening for human leukocyte antigen (HLA) antibodies. High-throughput screening platforms make this feasible for large blood centers. Which platform to use, donor subgroups to screen, characteristics of detected antibodies, and operational impact of deferring reactive donors are important questions., Study Design and Methods: We screened 2462 plateletpheresis donor sera for HLA antibodies on automated instruments using HLA Class I and II enzyme-linked immunosorbent assays (ELISA) or a mixed Class I/II Luminex flow analyzer. Screen-reactive samples were further tested by manual Luminex single-antigen assay to determine antibody specificity, estimated corresponding antigen frequency, and signal strength., Results: Alloexposed females had the highest reactivity rate on both platforms (21.0%), with much lower rates for nonexposed individuals or transfused males (1.4%-5.4%). Increasing parity and more recent pregnancy increased their likelihood of screen reactivity. Deferring screen-reactive parous females would result in at least a 4.8% plateletpheresis donor base decrement. Supplemental testing showed higher rates of nonspecific or natural antibodies in ELISA screen-reactive alloexposed females (2.5%) than Luminex (0%). Both assays were more likely to identify antibodies directed against a larger number of HLA antigens and/or of presumed higher titer in alloexposed donors., Conclusion: A strategy screening only parous female donors is reasonable. Both automated HLA antibody detection platforms are easy to use and preferentially identify alloexposed individuals with antibodies of presumed higher titer directed against more recipient HLA antigens., (© 2010 American Association of Blood Banks.)

Background: A new apheresis instrument, the Amicus Separator with software versions 2.13 and 2.34, was evaluated for component yields, collection efficiency, and incidence of donor and transfusion recipient reactions. The Amicus was also compared to the Spectra Leukocyte Reduction System (LRS) with version 5 software., Study Design and Methods: Single and double apheresis platelets (APs) were collected at two locations. The targeted platelet yields were 4.0 x 10(11) for single APs and 6.8 x 10(11) for double APs. One location used a double-needle procedure, and the other used a single-needle procedure. Along with 28 of the Amicus procedures (14 at each of two locations), the same donors underwent single or double AP collections on the Spectra LRS. APs were tested for platelet yields and residual white cells. APs were transfused in three hospitals. Donor and transfusion recipient reactions and technical problems were documented., Results: The Amicus Separator efficiently collected single APs (n = 59) and double APs (n = 62) with mean platelet yields of 4.2 x 10(11) and 6.5 x 10(11), respectively. When inlet line alarms occurred in single-needle procedures, platelet yields were lower and collection times were longer. All APs were white cell-reduced below 5.0 x 10(6), and all but one AP were white cell-reduced below 1.0 x 10(6) without filtration. Component yields from the paired Amicus and Spectra LRS procedures were comparable. Collection times (excluding reinfusion/rinseback) were 20 to 23 minutes faster on the Amicus Separator. No serious donor or transfusion recipient reactions occurred., Conclusion: The Amicus Separator provided satisfactory platelet yields and collection efficiency, with shorter collection times than did the Spectra LRS, and it white cell-reduced components without filtration.

Background: There are conflicting data on the effect of irradiation and subsequent storage on the quality of platelet components., Study Design and Methods: The retention of platelet properties during storage of gamma-irradiated apheresis suspensions was studied in 22 apheresis components obtained on a cell separator with a specialized centrifugation chamber. Immediately after collection, each suspension was divided equally into two 1-L polyolefin containers. On Day 1 (n = 12) and Day 3 (n = 10) one of each pair of suspension containers was gamma radiated with 2500 cGy. All platelet suspensions were stored for 5 days at 20 to 24 degrees C. Samples were drawn on Day 5 from each of the 22 pairs of containers for evaluation of an array of in vitro properties. Samples were taken from 10 pairs of containers for platelet labeling with either 51Cr or 111In for subsequent transfusion and concurrent in vivo measurement of recovery and survival. Posttransfusion samples were drawn after 24 hours for ex vivo whole blood aggregation., Results: Comparable in vitro and in vivo properties were measured in irradiated and control platelets, whether irradiation was performed on Day 1 or Day 3. The mean +/- 1 SD in vivo recovery and survival time for controls and platelets irradiated on Day 1 was 52 +/- 14 percent and 146 +/- 34 hours and 51 +/- 7 percent and 147 +/- 36 hours, respectively. For Day 3 irradiation, the values were 46 +/- 12 percent and 150 +/- 60 hours and 47 +/- 9 percent and 151 +/- 53 hours, respectively. A small, but measurable adverse effect of irradiation on ex vivo platelet aggregation was present., Conclusion: These data indicate that storage of apheresis platelets after gamma radiation is without clinically significant, demonstrably adverse effects on platelet quality.

Background: Determination of the white cell (WBC) count in WBC-reduced platelet components requires methods that have a detection limit in the range of approximately 5.0 x 10(2) to 5.0 x 10(4) per mL., Study Design and Methods: With a 50-microL Nageotte hemocytometer and bright-field microscopy (200x magnification), studies were conducted to develop and validate a method that could be used routinely with filtered and apheresis-harvested platelets. A 1-in-5 dilution of sample with a commercially available blood-diluting fluid was used because, with a lower (1-in-2) dilution, the observed number of WBCs was substantially less than the number expected at relatively high platelet counts (> 1.9 x 10(9)/mL)., Results: The observed and expected WBC counts in WBC-reduced platelet samples correlated well at levels between approximately 5 and 1100 WBCs per counting area (5.0 x 10(2)-1.1 x 10(5)/mL). At levels of more than 300 to 400 WBCs per counting area, accurate counts were obtained when 10 of the 40 rectangles were counted., Conclusion: These studies provide data to confirm that the 50-microL Nageotte hemocytometer can be used to accurately count low levels of WBCs in platelet components.