A. Heaton

In vivo regeneration of red cell 2, 3-diphosphoglycerate following transfusion of DPG-depleted AS-1, AS-3 and CPDA-1 red cells

Regeneration of 2, 3‐diphosphoglycerate (DPG) was determined following transfusion of DPG‐depleted group O red cells into group A recipients. Blood from five donors was stored in the adenine‐containing solutions CPDA‐1, AS‐1 or AS‐3 for 35 d at 4°C. Post‐transfusion red cell DPG and ATP were measured in separated group O red cells over a 7 d period. The studies confirmed rapid in vivo DPG regeneration with ≥ 50% of the maximum level being achieved within 7 h. An average of 95% of the recipients’ pre‐transfusion DPG level was achieved by 72 h and by 7 d mean (±SEM) DPG levels relative to recipients pre‐transfusion DPG averaged 84% (± 13%), 92% (± 17%) and 84% (± 21%) for CPDA‐1, AS‐1 and AS‐3 red cells, respectively. Results were comparable to those previously reported for blood stored in ACD for 15‐20 d (Valeri & Hirsch, 1969; Beutler & Wood, 1969). The immediate regeneration rate, V, closely approximated first order regeneration kinetics with AS‐3 red cells exhibiting double the rate of CPDA‐1 red cells (P<0·001). AS‐1 red cells exhibited an intermediate rate of regeneration which was not significantly different compared to either CPDA‐1 or AS‐3 (P>0·05). V exhibited a significant (P<0·05) positive correlation with ATP levels 5‐7 h post‐infusion. ATP regeneration of the infused cells was rapid with a mean increase of 1·2 μmol/g Hb above post‐storage levels being achieved 1 h following transfusion.

Post‐transfusion recovery of function of 5‐day stored platelet concentrates

Summary Platelets show a rapid reduction in their responsiveness to aggregating agents during storage for transfusion, but little is known about reversal of this defect in vivo after transfusion. In this study, fresh and stored platelets from the same donor (n=12) were labelled with 111In or 51Cr, respectively, mixed, and simultaneously infused. Blood samples were taken for up to 5 d post‐infusion, and the functional behaviour of the labelled platelets ex vivo was measured by retention on glass bead columns, and by whole blood aggregability to ADP, epinephrine and ristocetin. Aggregation was determined by filtering aggregated samples through a column of cotton wool to remove the aggregates, and quantitated as per cent decrease in radioactive counts. The study showed that, although infused radiolabelled 5 d stored platelets had a significantly lower aggregability towards ADP and epinephrine immediately (1 h) after infusion (32% and 29%, respectively, of fresh platelet values), a complete restoration to fresh platelet levels was found 24–72 h post‐infusion, with no further change observed over the ensuing 5 d with either fresh or stored labelled platelets. A slightly (6–9%) lower adhesion to both uncoated and collagen‐coated beads was found for the stored platelets throughout the 5 d period of study post‐infusion.

Paired comparison of platelet concentrates prepared from platelet‐rich plasma and buffy coats using a new technique with 111In and 51Cr

Two techniques for the preparation of platelet concentrate (PC), the standard platelet‐rich plasma (PRP) and buffy coat (BC) methods, were compared in nine paired studies with regard to platelet harvest, white cell (WBC) contamination, and PC quality after 5 days of 22°C storage. Platelet harvest using the BC method averaged approximately 56 percent of the whole blood level (6.2 × 1010/concentrate), which was less than the 76 percent achieved with the PRP‐PC method (8.7 × 1010/concentrate). An additional 5 units collected into an experimental siphon bag for BC‐PC processing showed improved platelet harvest (6.7 × 1010/concentrate, or approx. 70% of whole blood). WBCs remaining in the BC‐PC averaged 0.19 × 108 per unit compared to 3.6 × 108 per unit for PRP‐PC. Buffy coat processing produced red cell (RBC) units with 50 percent of the WBC contamination of conventionally prepared units (9.8 ± 6.2 × 108/unit vs. 18.9 ± 7.1 × 108/unit). The siphon bag further reduced WBC levels in the AS‐3 RBC units (6.4 ± 3.7 × 108/unit). In vitro studies performed on Days 1 and 5 after collection showed no significant differences in platelet metabolic and biologic function or cell integrity. β‐thromboglobulin and surface glycoprotein levels, indicators of platelet activation and membrane alteration, respectively, did not differ significantly in the PRP‐PC and BC‐PC; nor was lactate production higher in PRP‐PC, despite the substantially higher WBC counts. Autologous in vivo platelet viability determinations were performed by using concurrent transfusion of 111In‐labeled freshly drawn platelets and 51Cr‐labeled stored platelets. Paired f test analysis of BC‐PC versus PRP‐PC indicated no significant differences in platelet recovery and survival after 5 days of 22°C storage in polyolefin containers. Therefore, these studies confirm the equivalence of PC quality, comparable platelet harvest with the siphon bag, and decreased WBC contamination with the BC method.

Concurrent label method with 111In and 51Cr allows accurate evaluation of platelet viability of stored platelet concentrates.

Summary. The precision and reproducibility of 111In and 51Cr platelet radiolabel agents for in vivo kinetic studies of stored platelet concentrates (PC) were investigated. The objective was to develop a precise method with concurrent labelling of two platelet populations using different isotopes, which would allow identification of small differences in in vivo platelet quality. Identical labelling procedures were used to investigate the effects of PC storage age, different methods of red cell (RBC) and white cell (WBC) contamination correction, and label elution correction on the results of 111In and 51Cr kinetic studies.

In vitro platelet ageing at 22°C is reduced compared to in vivo ageing at 3 7°C

Summary .In these studies, platelet ageing during in vitro at 22°C was compared with in vivo ageing using isotope labelling. Paired fresh and 5‐d‐stored platelets had a mean residual life‐span (MRL) of 4–8 ± 0–7d and 3–2 ± 0–9 d, respectively. After 2–1 ± 0–4 d in vivo circulation, the MRL of the fresh platelets was equivalent to that of the 5‐d‐stored in vitro platelets. This suggests that platelet ageing for 5 d in vitro at 22°C corresponds to 2–1 d in vivo ageing at 37°C. Thus, the relative ageing at 22°CC in vitro was (2.1 d/ 5d) = 0–42 of that at 37°C in vivo. A similar ageing ratio (0–44) was obtained by measurement of the decrease in MRL during storage at 22°C of platelets stored for 1, 5, 7, 10 and 14 d relative to the decrease in MRL of fresh platelets in vivo.

Studies on platelets exposed to or stored at temperatures below 20°C or above 24°c

BACKGROUND: Platelet concentrates (PCs) may be subjected to temperatures outside 20 to 22 degrees C during shipping or storage, which may have an adverse effect on platelet quality. STUDY DESIGN AND METHODS: These studies systematically evaluated the effect of short- term exposure (≤ 24 hours) of platelets to temperatures above 22° or below 20° C as part of standard 5-day PC storage at 22° C, as well as the effect of long-term storage (5 days) at 24 and 26° C. For the short-term exposure studies, up to 6 units of Day 1 standard PCs were mixed, split, and returned to the containers. Test units were then stored without agitation in an incubator at a specific temperature (4, 12, 16, or 18° C) for various times up to 24 hours, after which they were stored with agitation at 22° C. One unit acted as control and was stored at 20 to 22° C throughout the 5-day storage period. Loss of platelet discoid shape was determined photometrically by the extent of shape change assay, by an increase in apparent platelet size by morphologic evaluation, and by swirling. RESULTS: A gradual loss of platelet discoid shape occurred at temperatures below 20° C. For similar periods, a greater difference between test and control PCs was observed in units held at 4° C than in those held at 16° C. The data were fitted to an equation to relate platelet discoid shape (% of control) to exposure temperature and time. Assuming that a 20-percent decrease or more in the extent of shape change assay represents a significant loss in platelet viability, the equation predicts that such a loss occurs when the platelets are exposed to 16° C for ≥16 hours, to 12° C for ≥10 hours, or to 4°C for ≥6 hours, whereas exposure to 18° C for ≤24 hours has no significant effect. Storage for 5 days at temperatures ≤26° C was not associated with any significant reduction in platelet discoid shape or other measures of platelet quality. CONCLUSION: There was a gradual loss of platelet discoid shape at exposure temperatures < 20°C, which worsened as temperatures decreased and exposure times increased to 24 hours. This relationship can be described in an equation that could be used as a guideline for allowable exposure conditions.BACKGROUND: Platelet concentrates (PCs) may be subjected to temperatures outside 20 to 22 degrees C during shipping or storage, which may have an adverse effect on platelet quality.

Storage of ADSOL-Preserved Red Cells at 2.5 and 5.5°C: Comparable Retention of in vitro Properties1

Abstract. Previous studies with CPDA‐1 and Nutricel preserving solutions indicated that red cell properties were affected by small differences in storage temperature. The influence of a 3°C differential on the preservation of the in vitro properties of ADSOL‐preserved (AS‐1) red blood cells was investigated in a paired study. AS‐1 red blood cells were stored at 2.5 and 5.5°C for 42 days. Extent of hemolysis, glucose consumption and pH levels were comparable at the two storage temperatures. Lactate levels were slightly, but significantly higher at 5.5°C. ATP levels were slightly but significantly higher at 2.5°C, only during the later part of the storage period. 2.3‐DPG levels were slightly better retained at 2.5°C after 7 days of storage. Holding units of whole blood for either 1 or 8h at ambient temperature after phlebotomy prior to processing did not influence the types of temperature‐dependent changes. The differences as a function of storage temperature were small and appear to be of no practical importance in connection with the storage of AS‐1 red blood cells.

QUALITY OF PLATELET CONCENTRATES

Despite the current emphasis in transfusion medicine on regulatory compliance and cost containment, there is continuing activity in quality improvement of blood products. Quality can be assessed by measuring both benefit and risk. High quality products are those in which the benefit is maximized and the risk minimized. Risk, in the context of platelet transfusions, is minimized by reducing infectious agents, sources of allergic reactions, and other factors likely to cause adverse reactions in recipients. Benefit can be better described as potency. Potency is the ability to produce a desired effect. For platelet concentrates, potency has both quantitative [platelet yield] and qualitative [platelet viability, survival, and function] components. There are many activities which may influence the potency of the final transfused platelet product and these are summarized in Figure 1. It is helpful to review each step in order to assess the potential impact on the potency of the final transfused product.

Clinical benefits of leukodepleted blood products

1. Introduction.- 2. Methods of Leukodepletion.- 3. Enumeration of Low White Cells.- 4. Mechanisms of Leukodepletion by Filtration.- 5. Role of Contaminating White Blood Cells in the Storage Lesions of Red Cells and Platelets.- 6. Leukodepletion to Prevent Transfusion Reactions: Effects on Cytokines and Other Biologic Response Modifiers.- 7. Leukodepletion and Alloimmunization.- 8. Role of Donor Leukocytes and Leukodepletion in Transfusion-Associated Viral Infections.- 9. Leukocyte Depletion and Transfusion-Induced Immunomodulation.- 10. The Role of Leukocyte Depletion in Prevention of Transfusion-Related Acute Lung Injury.- 11. The Role of Leukocyte Depletion in the Prevention of Reperfusion Injury Associated with Open Heart Surgery.- 12. The Use of Leukodepleted Blood Components for Neonates and Infants.- 13. Leukocyte Depleted Blood Transfusion in Hematopoietic Stem Cell Reconstitution Therapy.- 14. Cost-Effectiveness of Leukodepletion.

Role of Contaminating White Blood Cells in the Storage Lesions of Red Cells and Platelets

Red cell concentrates prepared from whole blood donations without buffy coat removal contain the majority of the original white cells contained in the whole blood donation. These white cells are predominantly granulocytes. Granulocytes may be metabolically active and release oxidant radicals. They certainly degenerate rapidly on storage, releasing proteolytic enzymes. Such substances may damage the red cell membrane, resulting in accelerated glycolysis, possibly to supply ATP for the sodium/potassium pump, followed by in vitro hemolysis and diminished in vivo recovery or survival.