Pooled Platelet Concentrates Research Articles

Evaluation of storage conditions of platelet concentrates prepared from pooled buffy coats.

Five days storage of pooled platelet concentrates (PCs) with high yields often results in a pH fall and poor platelet morphology despite the use of specific containers. In this study we evaluated two techniques for prolonged storage of PCs with high platelet counts, by measuring pH and platelet swirl. In routine procedures, 90 PCs, prepared from five buffy coats, were stored in a single 1-litre PL 732 container. After 5 days storage, 51 PCs with platelet counts below 3.1 x 10(11)/U showed a pH above 6.8 and optimal swirling scores. 29 of 39 PCs (74%) with yields above 3.1 x 10(11)/U showed pH values below 6.8 and poor swirling scores. These poor results can be prevented by shortening the duration of storage. PCs with high yields can be stored for 5 days either by dividing the concentrate into two containers or by adjusting the platelet count to 3.1 x 10(11)/U. In the latter procedure, we reduced the volume of the concentrate and found that of 102 PCs, only 9 showed poor values for pH and platelet swirl. The data clearly indicate the importance of measuring the prestorage platelet count to select the optimal procedure for concentrate storage.

Pooled platelet concentrates prepared by the platelet-rich-plasma method and filtered with three different filters and stored for 8 days.

Pooled platelet concentrates (PC) prepared by the platelet-rich plasma (PRP) method were filtered with three different filters and stored for 8 days at room temperature. The effect of filtration on leukocyte contamination, platelet concentration, and the in vitro function, morphology, metabolism and activation of platelets were studied. Eight pools of 20 PRP-PC were used, each pool was split into 4 equal volumes; 3 were filtered over a PL50HF, a PL-10A and a Bio P10 filter, the 4 served as a control. After filtration, leukocyte counts exceeded 3 x 10(5) in none of the pooled PC. Platelet loss induced by filtration was about 17%. During storage, no differences in pH, PCO2, and lactate and glucose concentration were found between the filtered and the unfiltered units, nor were any differences observed between filtered and unfiltered pooled PC in aggregation upon stimulation with collagen and/or ADP, adhesion capacity to collagen in flowing blood, nucleotide content of the platelets and nucleobase concentration in the plasma, expression of activation-dependent antigens, or platelet morphology as observed by light microscopy and by the swirling effect. Selective removal of beta-thromboglobulin (22%) by the PL50HF filter was observed. Pooled PC prepared by the PRP-method can be filtered and stored for 8 days without detrimental effect on platelet function, metabolism or activation.

Storage of pools of six and eight platelet concentrates.

Platelet concentrates (PCs) prepared from units of whole blood are routinely stored singly at 20 to 24 degrees C and pooled prior to transfusion. Studies have been conducted to evaluate the in vitro properties of pools of six (n = 19) and eight (n = 17) ABO-identical PCs after storage, with comparative studies involving single units (n = 33). The pools were prepared using the sterile connecting device. One-day-old and 3-day-old PCs were pooled and stored for a total of 5 days in a container system consisting of two 1000-mL polyolefin containers. The pooled platelet suspension was divided approximately equally between the two containers. The platelet count was reduced by less than 5 percent during storage of the pools, which is similar to the reduction found with storage of control units of single PCs. The volume loss due to pooling was 9.6 +/- 1.9 percent (mean +/- 1 SD). The pH of the PC pools was approximately 7.0 after 5 days of storage, with no pool having a pH below 6.2. In vitro platelet properties, such as morphology score, extent of shape change induced by ADP, total ATP, aggregation response to ADP and collagen, response to hypotonic stress, lactate dehydrogenase discharge, and beta-thromboglobulin release, were similar for pools and control single PCs. In addition, comparable low levels of thymidine uptake were detected in the mononuclear leukocyte fraction of pooled and unpooled PCs that were stored for 5 days at 20 to 24 degrees C, which indicates that the mixing of lymphocytes in the pool did not stimulate in vitro immunologic reactions.(ABSTRACT TRUNCATED AT 250 WORDS)

Incubation of platelet concentrates before transfusion does not improve posttransfusion recovery

Incubation of stored platelet concentrates (PCs) at 37 degrees C for 1 hour has been reported to result in a better morphology score and improved platelet recovery. A study was conducted in adult patients with leukemia to determine whether incubation of stored PCs results in an improved platelet recovery as measured by 10-minute posttransfusion corrected count increments (CCI). Eligible patients had platelet counts of less than 30,000 per microL and were clinically stable. Patients were transfused with 6 to 10 units of PC stored for 3 days (15 studies) or 4 days (5 studies). Platelets were pooled and then split in two equal volumes so that each patient received two sequential half-transfusions, one incubated at 37 degrees C for 1 hour and the other kept at 22 degrees C for 1 hour. Patients were randomized as to which half-transfusion was received first. The mean CCI of the incubated half-transfusions was 13.6 x 10(3) when they were given first and 14.5 x 10(3) when given second; this was not significantly different from the mean CCI of the nonincubated half-transfusions: 13.8 x 10(3) when they were given first and 13.8 x 10(3) when given second. In contrast to earlier reports, it can be concluded that incubation of pooled PCs does not improve platelet recovery.

Donor selection for alloimmunized patients by platelet crossmatching of random‐donor platelet concentrates

Samples obtained from bag segments of stored platelet concentrates (PCs) were crossmatched with sera from alloimmunized patients to identify potentially compatible donors. Sera from 41 patients who were refractory to random-donor platelet transfusions were tested. All sera had lymphocytotoxic antibody (LCTAb), and 37 patients had LCTAb that reacted strongly against greater than 75 percent of the cells in the panel. At least 18 units of PCs were tested per patient. Sera from 33 patients were tested by microenzyme-linked immunosorbent assay (microELISA). Crossmatches with 703 (74 percent) of 944 PCs were positive, 23 percent were negative, 3 percent were indeterminant. Eight additional patients were also tested with a solid-phase system; 352 (85 percent) of 417 crossmatches were positive and 15 percent were negative. Patients with more reactive LCTAb had very few (often 0-2) in vitro compatible units. Thirty-four transfusions of pooled compatible PCs, all stored less than 3 days, were administered to clinically evaluable patients. Six of 20 transfusions selected by microELISA produced satisfactory increases (corrected count increments [CCIs] greater than 7500) 10 minutes after transfusion in 4 of 14 patients. Eight of 14 transfusions selected by solid-phase produced CCIs greater than 7500 in 5 of 8 patients. Although it is difficult to select large numbers of compatible units for heavily alloimmunized patients by these techniques, some transfusions were successful in patients who had very few HLA-compatible donors. This approach may be of particular value in emergency situations.

Storage of pooled platelet concentrates. In vitro and in vivo analysis.

The use of sterile connecting devices will permit up to 5-day storage of pooled platelet concentrates (PCs). However, there are no data evaluating long-term storage of PCs pooled from multiple donors. Four units of ABO-compatible or -incompatible PCs were pooled and stored in single 300-ml PL-732 storage bags for up to 5 days. Results of in vitro assays showed acceptable storage values regardless of the ABO types in the pool. Pool pH on Day 5 was 6.83 +/- 0.3 (mean +/- 1 SD). The in vitro storage characteristics were comparable to those of unpooled age-matched platelets reported previously from our laboratory. For in vivo studies, 4-unit pools of ABO-compatible random-donor PCs stored for up to 96 hours in 1000-ml PL-732 bags were transfused into patients who were thrombocytopenic due to bone marrow failure, and the correct count increments (CCI) were determined. In vivo results showed a mean 1-hour CCI of 11,368 +/- 5824 for the pooled stored platelets and 7819 +/- 5189 for unpooled controls (p greater than 0.05). To evaluate the possibility that passenger lymphocytes in the concentrates would generate mixed lymphocyte reactions (MLR) in the pooling bag during storage, lymphocytes were studied over 5 days of storage by the use of monoclonal antibodies against activated T-cell markers and by 3H thymidine uptake. Results failed to show evidence of either the generation of activated T-cell markers or the uptake of 3H thymidine.(ABSTRACT TRUNCATED AT 250 WORDS)

Escherichia coli Sepsis From Contaminated Platelet Transfusion

Transfusion of pooled platelet concentrate (PC) caused a septic reaction characterized by sustained hypotension, high cardiac output, and low systemic vascular resistance. Investigation demonstrated the same strain of Escherichia coli in the patient's blood, the transfused pooled PC, and recalled packed red blood cells separated from the same unit of whole blood as one of the platelet units in the contaminated pool. Five hundred other units of PC from the same supplier were cultured prospectively, and 7% were bacterially contaminated. The level of contamination was 20 or fewer colony-forming units per milliliter in all except one unit, the only one associated with a febrile transfusion reaction. This episode illustrates the continuing importance of sepsis as a cause of platelet transfusion reactions and demonstrates the usefulness of appropriate cultures and epidemiologic information in assessing the source.

A Randomized Trial of Leukocyte-Depleted Platelet Transfusion to Modify Alloimmunization in Patients With Leukemia

In an effort to determine whether the use of leukocyte (WBC) depleted platelets could modify the development of alloimmunization, 98 adult patients with acute nonlymphocytic leukemia receiving initial induction therapy were randomized to receive standard pooled platelet concentrates (PC) or WBC-depleted PC. WBC depletion was produced by an additional centrifugation of pooled PC, with removal of 81% of WBC and an associated platelet loss of 27%. Lymphocytotoxic antibody (LCTAb) levels were monitored as a serologic marker of alloimmunization. Overall, 5 of 25 evaluable patients receiving WBC-depleted PC developed LCTAb, compared to 13/31 receiving standard PC (p = 0.071). There was no significant difference in alloimmunization rate in the subgroup of patients who had no previous exposure to histocompatibility antigens by pregnancy or prior transfusions (4/15 alloimmunized receiving WBC depleted versus 4/12 receiving standard PC). There was no difference in the number of patients in each group who required HLA-matched platelets during induction therapy. In view of the significant loss of platelets with WBC depletion, the expense and difficulty of providing WBC-poor RBC, the absence of impact on the need for HLA-matched platelets during induction, and the small potential benefit from this approach, WBC-depleted platelets should not be utilized to prevent alloimmunization in patients with leukemia.

A randomized trial of leukocyte-depleted platelet transfusion to modify alloimmunization in patients with leukemia

In an effort to determine whether the use of leukocyte (WBC) depleted platelets could modify the development of alloimmunization, 98 adult patients with acute nonlymphocytic leukemia receiving initial induction therapy were randomized to receive standard pooled platelet concentrates (PC) or WBC-depleted PC. WBC depletion was produced by an additional centrifugation of pooled PC, with removal of 81% of WBC and an associated platelet loss of 27%. Lymphocytotoxic antibody (LCTAb) levels were monitored as a serologic marker of alloimmunization. Overall, 5 of 25 evaluable patients receiving WBC-depleted PC developed LCTAb, compared to 13/31 receiving standard PC (p = 0.071). There was no significant difference in alloimmunization rate in the subgroup of patients who had no previous exposure to histocompatibility antigens by pregnancy or prior transfusions (4/15 alloimmunized receiving WBC depleted versus 4/12 receiving standard PC). There was no difference in the number of patients in each group who required HLA-matched platelets during induction therapy. In view of the significant loss of platelets with WBC depletion, the expense and difficulty of providing WBC-poor RBC, the absence of impact on the need for HLA-matched platelets during induction, and the small potential benefit from this approach, WBC- depleted platelets should not be utilized to prevent alloimmunization in patients with leukemia.