Platelet transfusion - the art and science of compromise

Influence of donor age, sex and ethnicity on high-titre anti-A and -B: Review of 6 million donations from two national blood providers

BACKGROUND AND OBJECTIVES

Some blood operators routinely screen blood donations for high-titre (HT) anti-A/B to reduce the risk of a haemolytic transfusion reaction due to out-of-group plasma-rich components. We assessed donor factors associated with an increased likelihood of screening positive and compared routine data between England and Australia.

MATERIALS AND METHODS

Data were assessed from HT screening during 2018-2020 in Australia and 2018-2021 in England, totalling nearly 6 million blood donations. Screening was performed using a Beckman Coulter PK7300 analyser with a micro-titre plate saline direct agglutination test in both countries, although different reagent red cells were chosen. HT-positive was defined as testing positive at a titre of 128 or above.

RESULTS

The likelihood of a donor testing HT-positive was greater for females than males, declined with age and was dependent on the ABO group. However, the proportion of donors testing HT-positive was consistently higher in Australia than in England: overall, 14% of group O donations and 5% of group A donations in England tested HT-positive, compared with 51% and 22%, respectively in Australia. English data also showed that donors from Black, Asian or mixed ethnic backgrounds were more likely to test HT-positive than White donors.

CONCLUSION

These data demonstrate that donor sex, age, ABO group and ethnicity affect the likelihood of testing HT-positive. Differences in testing methods likely had a significant impact on the proportion of donors testing as HT-positive or -negative rather than any differences in donor populations.

Isohemagglutinin titration in pooled and apheresis platelets

BACKGROUND

Platelet inventory constraints necessitate ABO-incompatible platelet transfusion. Many minimize the hemolytic impact by confirming low titre (LT) donor isohemagglutinins. This process is costly. Pathogen-reduced platelets (PRP) in platelet additive solutions (PAS) will dilute plasma and decrease high-titre isohemagglutinins (HT). We determined the proportion of HT platelets and incompatible transfusions for units suspended in plasma to reassess the need for titres following introduction of PRP/PAS.

STUDY DESIGN AND METHODS

Our titre method is manual tube (1:50) dilution of platelet supernatant from apheresis or whole blood derived buffy coat pools suspended in plasma, tested with A1/B red cells. Testing included 49,058 pooled and 11,738 apheresis platelets over 4 years. The HT proportion, rate of out-of-group transfusions, and hemolytic reactions were determined. The impact of PAS dilution was estimated.

RESULTS

Totally 60,796 platelet units were tested. Group O pooled and group B apheresis platelets had HT in 6.6% and 5.7%, respectively. Group A pooled and apheresis platelets included 2% with HT. Approximately 25% of platelets transfused were ABO-incompatible and no hemolytic reactions were reported. Based on the proportions of PAS-E and plasma for PRP platelets, plasma from each donor comprises 11 mL (6% of total volume) vs 20-257 mL in untreated pools. PAS-E will replace and dilute residual plasma by at least 50%.

DISCUSSION

Rare platelet pools may demonstrate HT. PRP platelets with PAS will reduce titres and may abrogate the need for titration. A strategy of group specific transfusion or transfusion of group A PRP platelet transfusions may be a safe alternative.

Anti-D immunization after D positive platelet transfusions in D negative recipients: A systematic review and meta-analysis

BACKGROUND

Anti-D can be formed after D-incompatible platelet transfusions due to contaminating D+ red blood cells. These antibodies are of particular importance in women of childbearing potential, because anti-D is most often involved in severe cases of hemolytic disease of the fetus and newborn. This systematic review determined the frequency of anti-D after D+ platelet transfusions and risk factors for D alloimmunization.

STUDY DESIGN AND METHODS

Relevant literature was searched using PubMed, Embase and Web of Science until December 2022. Overall anti-D frequency and risk factors were estimated using a random effects meta-analysis.

RESULTS

In 22 studies, a total of 3028 D- patients received a mean of six D+ platelet transfusions. After a mean follow-up of seven months 106 of 2808 eligible patients formed anti-D. The pooled anti-D frequency was 3.3% (95% CI 2.0-5.0%; I2 71%). After including only patients with an undoubtable follow-up of at least 4 weeks, 29 of 1497 patients formed anti-D with a pooled primary anti-D rate of 1.9% (95% CI 0.9-3.2%, I2 44%). Women and patients receiving whole blood derived platelets had two and five times higher anti-D rates compared with men and patients receiving apheresis derived platelets, respectively.

DISCUSSION

Anti-D immunization is low after D incompatible platelet transfusions and dependent on recipients' sex and platelet source. We propose anti-D prophylaxis in girls and women, capable of becoming pregnant in the future, that received D+ platelets, regardless of platelet source, to reduce the risk of anti-D induced hemolytic disease of the fetus and newborn.

Anti-D Alloimmunization Following Rhesus-Incompatible Platelet Transfusion in a Myelodysplastic Syndrome Patient

Patients with myelodysplastic syndrome (MDS) often need platelet transfusions to address thrombocytopenia. The risk of alloimmunization, particularly in Rhesus (Rh) incompatibility between donors and recipients during platelet transfusions, is heightened, especially with whole blood-derived pooled platelets as opposed to apheresis platelets. Although the occurrence of alloimmunization from platelet transfusions is minimal, there is an ongoing debate about whether Rh immune globulin (RhIg) should be administered to Rhesus D (RhD)-negative recipients of RhD-positive platelet units. We present a unique case of anti-D alloimmunization in a 56-year-old patient with underlying MDS following multiple platelet transfusions but never received packed cell transfusion or anti-D immunoglobulin. Some studies advocate for RhIg administration in specific scenarios and for certain patient populations. This case underscores the importance of considering Rhesus compatibility or administering anti-D immunoglobulin in cases where frequent platelet transfusions are required.

Separation of platelets by size in a microfluidic device based on controlled incremental filtration

The significant biological and functional differences between small and large platelets suggested by recent studies could have profound implications for transfusion medicine. However, investigating the relationship between platelet size and function is challenging because separating platelets by size without affecting their properties is difficult. A standard approach is centrifugation, but it inevitably leads to premature activation and aggregation of separated platelets. This paper describes the development and validation of a microfluidic device based on controlled incremental filtration (CIF) for separating platelets by size without the cell damage and usability limitations associated with centrifugation. Platelet samples derived from whole blood were used to evaluate the dependence of the CIF device separation performance on design parameters and flow rate, and to compare the properties of PLT fractions generated by the CIF device with those produced using a centrifugation protocol in a split-sample study. This was accomplished by quantifying the platelet size distribution, mean platelet volume (MPV), platelet-large cell ratio (P-LCR) and platelet activation before and after processing for all input and output samples. The 'large platelet' fractions produced by the CIF device and the centrifugation protocol were essentially equivalent (no significant difference in MPV and P-LCR). Platelets in the 'small platelet' fraction produced by the CIF device were significantly smaller than those produced by centrifugation (lower MPV and P-LCR). This was because the CIF 'small platelet' fraction was contaminated by much fewer large platelets (∼2-times lower recovery of >12 fL platelets) and retained the smallest platelets that were discarded by the centrifugation protocol. There was no significant difference in platelet activation between the two methods. However, centrifugation required a substantial amount of additional anticoagulant to prevent platelet aggregation during pelleting. Unlike centrifugation, the CIF device offered continuous, flow-through, single-step processing that did not cause platelet aggregation. Such a capability has the potential to accelerate the basic studies of the relationship between platelet size and function, and ultimately improve transfusion practice, particularly in the pediatric setting, where the need for low-volume, high-quality platelet transfusions is most urgent.

What's in Your Transfusion? A Bedside Guide to Blood Products and Their Preparation

An understanding of the contents of blood products and how they are modified before transfusion will help any physician. This article will review five basic blood products and the five most common product modifications.

What Laboratory Tests and Physiologic Triggers Should Guide the Decision to Administer a Platelet or Plasma Transfusion in Critically Ill Children and What Product Attributes Are Optimal to Guide Specific Product Selection? From the Transfusion and Anemia EXpertise Initiative-Control/Avoidance of Bleeding

OBJECTIVES

To present consensus statements and supporting literature for plasma and platelet product variables and related laboratory testing for transfusions in general critically ill children from the Transfusion and Anemia EXpertise Initiative-Control/Avoidance of Bleeding.

DESIGN

Systematic review and consensus conference of international, multidisciplinary experts in platelet and plasma transfusion management of critically ill children.

SETTING

Not applicable.

PATIENTS

Critically ill pediatric patients at risk of bleeding and receiving plasma and/or platelet transfusions.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A panel of 10 experts developed evidence-based and, when evidence was insufficient, expert-based statements for laboratory testing and blood product attributes for platelet and plasma transfusions. These statements were reviewed and ratified by the 29 Transfusion and Anemia EXpertise Initiative - Control/Avoidance of Bleeding experts. A systematic review was conducted using MEDLINE, EMBASE, and Cochrane Library databases, from inception to December 2020. Consensus was obtained using the Research and Development/University of California, Los Angeles Appropriateness Method. Results were summarized using the Grading of Recommendations Assessment, Development, and Evaluation method. We developed five expert consensus statements and two recommendations in answer to two questions: what laboratory tests and physiologic triggers should guide the decision to administer a platelet or plasma transfusion in critically ill children; and what product attributes are optimal to guide specific product selection?

CONCLUSIONS

The Transfusion and Anemia EXpertise Initiative-Control/Avoidance of Bleeding program provides some guidance and expert consensus for the laboratory and blood product attributes used for decision-making for plasma and platelet transfusions in critically ill pediatric patients.

Essential Role of Rho-Associated Kinase in ABO Immune Complex-Mediated Endothelial Barrier Disruption

ABO immune complexes (ABO-IC) formed by ABO-incompatible antigen-antibody interaction are associated with hemolysis and platelet destruction in patients transfused with ABO-nonidentical blood products. However, the effects of ABO-IC on endothelial cells (EC) are unclear. ABO-IC were formed in vitro from normal donor-derived plasma and serum. Human pulmonary artery EC (HPAEC) were cultured and treated with media, ABO-identical and –non-identical plasma, and ABO-IC. EC barrier integrity was evaluated using transendothelial electrical resistance (TEER), scanning electron microscopy (SEM), vascular endothelial (VE)-cadherin and phalloidin staining, and Rho-associated Kinase (ROCK) inhibitor treatment. TEER revealed significant/irreversible barrier disruption within 1–2 h of exposure to ABO non-identical plasma and ABO-IC; this occurred independently of EC ABO type. Treatment with ABO-IC resulted in decreased VE-cadherin staining and increased phalloidin staining in a time-dependent manner, suggesting that the resultant increased EC barrier permeability is secondary to actin stress fiber formation and loss of cell surface VE-cadherin. Inhibition of ROCK was effective in protecting against IC-induced barrier disruption even two hours after ABO-IC exposure. ABO-IC causes increased EC barrier permeability by decreasing cell surface VE-cadherin and promoting stress fiber formation, which is preventable by inhibiting ROCK activation to protect against EC contraction and gap formation.

The rebirth of the cool: a narrative review of the clinical outcomes of cold stored low titer group O whole blood recipients compared to conventional component recipients in trauma

There has been renewed interest in the use of low titer group O whole blood (LTOWB) for the resuscitation of civilian casualties. LTOWB offers several advantages over conventional components such as providing balanced resuscitation in one bag that contains less additive/preservative solution than an equivalent volume of conventional components, is easier and faster to transfuse than multiple components, avoids blood product ratio confusion, contains cold stored platelets, and reduces donor exposures. The resurgence in its use in the resuscitation of civilian trauma patients has led to the publication of an increasing number of studies on its use, primarily amongst adult recipients but also in pediatric patients. These studies have indicated that hemolysis does not occur amongst adult and pediatric non-group O recipients of a modest quantity of LTOWB. The published studies to date on mortality have shown conflicting results with some demonstrating a reduction following LTOWB transfusion while most others have not shown a reduction; there have not been any studies to date that have found significantly increased overall mortality amongst LTOWB recipients. Similarly, when other clinical outcomes, such as venous thromboembolism, sepsis, hospital or intensive care unit lengths of stay are evaluated, LTOWB recipients have not demonstrated worse outcomes compared to conventional component recipients. While definitive proof of the trends in these morbidity and mortality outcomes awaits confirmation in randomized controlled trials, the evidence to date indicates the safety of transfusing LTOWB to injured civilians.

Does ABO and RhD matching matter for platelet transfusion?

Platelets express ABO antigens and are collected in plasma, which contains ABO antibodies as would be consistent with the donor ABO group. Platelet ABO antigens that are incompatible with recipient ABO antibodies may have accelerated clearance from circulation and result in lower count increments. ABO antibodies that are passively transferred from donor plasma may result in hemolysis of recipient red blood cells. Although platelets do not express Rh antigens, they contain small numbers of intact red blood cells or fragments, which can lead to alloimmunization in the recipient. Alloimmunization to the RhD antigen may occur when platelets obtained from RhD-positive donors are transfused to RhD-negative recipients. All of these compatibility considerations must be balanced against the available supply, which may be limited due to the 5- to 7-day shelf life of platelets. This articles describes considerations for platelet ABO and RhD selection for platelet transfusions, including the impact of major ABO incompatibility on count increments, the risks of hemolysis associated with minor ABO incompatibility, and the risk of RhD alloimmunization when RhD-negative patients receive platelets obtained from RhD-positive donors.

Identifying correlations between donor demographics and isohemagglutinin titers as a potential method to screen for low-titer group O whole blood

BACKGROUND

With more hospitals using low-titer group O whole blood in trauma resuscitation, having an efficient screening method for low-titer donors is critical. Our blood center uses an automated screen for high-titer isohemagglutinins in our platelet donations while collecting detailed donor demographic information. Using this data, we can identify key demographics often associated with titer status, thereby helping develop a donor-triaging method for titering.

STUDY DESIGN AND METHODS

Titer results were read with an automated microplate system as either high or low, based on agglutination, with a cutoff equivalent to 1:256 (both anti-A and anti-B). Donor demographic data analyzed included date of donation, blood group, age, gender, and ethnicity.

RESULTS

57,508 donations were collected from 2073 unique donors between 2014 and 2018. We found the following demographics to be correlated with titer status: gender, ABO blood group, age, and ethnicity. Variability in titer status was identified in 215 individuals. This represented around 10 % of the total unique donors and was split equally amongst gender. We also found that donors between the ages of 41-60 ha d the highest likelihood of having variability in titer status, peaking at 13 %, and this proportion declined past age 60.

CONCLUSION

Titer status is associated with the following donor demographics: gender, ABO type, age, and ethnicity. We also discovered that variability in titer status is correlated with age. In blood centers that do not have automated and routine titer screening procedure, these findings could be used as a method to efficiently identify low-titer donors a-priori.

Transfusion of blood components containing ABO-incompatible plasma does not lead to higher mortality in civilian trauma patients

BACKGROUND

This study investigated the effect on mortality of transfusing ABO-incompatible plasma from all sources during trauma resuscitation.

METHODS

Demographic, transfusion, and survival data were retrospectively extracted on civilian trauma patients. Patients were divided by receipt of any quantity of ABO-incompatible plasma from any blood product (incompatible group) or receipt of solely ABO-compatible plasma (compatible group). The primary outcome was 30-day mortality, while other outcomes included 6- and 24-hour mortality. Mixed-effects logistic regression was used to model the effect of various predictor variables, including receipt of incompatible plasma, on mortality outcomes.

RESULTS

Nine hospitals contributed data on a total of 2618 trauma patients. There were 1282 patients in the incompatible group and 1336 patients in the compatible group. In both the unadjusted and adjusted models, the 6-hour, 24-hour, and 30-day mortality rates were not significantly different between these groups. The patients in the incompatible group were then divided into high volume (>342 mL) and low volume (≤342 mL) incompatible plasma recipients. In the adjusted model, the high-volume group had higher 24-hour mortality when the Trauma Injury Severity Score survival prediction was >50%. Mortality at 6 hours and 30 days was not higher in this model. The low-volume group did not have increased mortality at any of the time points in this adjusted model.

CONCLUSION

The transfusion of incompatible plasma in civilian trauma resuscitation does not lead to higher 30-day mortality. The finding of higher mortality in a select group of recipients in the secondary analysis warrants further study.

Emergency Transfusions

Successful emergency transfusions require early recognition and activation of resources to minimize treatment delays. The initial goals should focus on replacement of blood in a balanced fashion. There is an ongoing debate regarding the best approach to transfusions, with some advocating for resuscitation with a fixed ratio of blood products and others preferring to use viscoelastic assays to guide transfusions. Whole-blood transfusion also is a debated strategy. Despite these different approaches, it generally is accepted that transfusions should be started early and crystalloid infusions limited. As hemodynamic stability is restored, endpoints of resuscitation should be used to guide the resuscitation.

Hemolytic markers following the transfusion of uncrossmatched, cold-stored, low-titer, group O+ whole blood in civilian trauma patients

BACKGROUND

Low-titer group O whole blood (LTOWB) is increasingly being used in the civilian trauma setting, although there is a risk of hemolysis. This study evaluated the impact on hemolytic markers following the transfusion of 4 or more units of uncrossmatched LTOWB.

METHODS

Civilian adult trauma patients who received four or more units of leukoreduced group O+, low-titer (<50 anti-A and anti-B), platelet-replete uncrossmatched whole blood during their initial resuscitation and who survived for more than 24 hours after the transfusion were included in this retrospective study. Lactate dehydrogenase (LDH), total bilirubin, haptoglobin, potassium, and creatinine were evaluated on the day of LTOWB transfusion (Day 0) and the next 3 days. Blood product administration over the first 24 hours of admission was recorded.

RESULTS

There were 54 non-group O and 23 group O recipients of four or more LTOWB units. The median (interquartile range [IQR]) number of transfused LTOWB units was 4 (4-5) and 4 (4-4), respectively, the maximum number in both groups was eight. The non-group O patients received a median (IQR) volume of 1470 mL (1368-2052) of ABO-incompatible plasma. Comparing the non-group O to the group O recipients, there were no significant differences in the haptoglobin, LDH, total bilirubin, potassium, or creatinine concentrations at any of the time points. There were no reported transfusion reactions.

CONCLUSION

Receiving at least four LTOWB units was not associated with biochemical or clinical evidence of hemolysis.

Platelet Transfusion: And Update on Challenges and Outcomes

Platelet transfusion is a common practice in onco-hematologic patients for preventing or treating hemorrhages. Platelet concentrates can be transfused with therapeutic or prophylactic purposes. With the aim to help clinicians to take the decisions on platelet transfusion, some guidelines have been developed based on the current scientific evidence. However, there are some controversial issues and available scientific evidence is not enough to solve them. There is little information about what is the best platelet product to be transfused: random platelets or single donor apheresis platelets, and plasma-suspended or additive solution suspended platelets. Platelets are often transfused without respecting the ABO compatibility, but influence of this practice on platelet transfusion outcome is not well established. In the prophylactic platelet transfusion set there are some questions unsolved as the platelet threshold to transfuse prior to specific procedures or surgery, and even if platelet transfusion is necessary for some specific procedures as autologous hematopoietic stem cell transplantation. A challenging complication raised from multiple platelet transfusions is the platelet transfusion refractoriness. The study and management of this complication is often disappointing. In summary, although it is a widespread practice, platelet transfusion has still many controversial and unknown issues. The objective of this article is to review the current evidence on platelet transfusion practices, focusing on the controversial issues and challenges.

Quality improvement with platelet additive solution for safer out-of-group platelet transfusions

Isoagglutinins in the plasma of apheresis platelets are a concern. High titer anti-A and anti-B can cause severe hemolytic transfusion reactions. Our facility is testing donor plasma using the gel method to identify isoagglutinin titers exceeding 250. Platelet additive solution (PAS), recently introduced as a collec-tion and storage solution, replaces approximately 65 percent of the plasma in a platelet component. We intended to confirm the effect of PAS on the isoagglutinin titers. We compared the isoagglutinin titers in donor plasma from EDTA-anticoagulated whole blood (without PAS) with the plasma in apheresis platelet components with PAS. Titers were determined in a buffered gel matrix test using serial twofold dilution steps. Among 100 donors tested, 26 plasma samples exceeded a threshold titer of 250; 25 were group O and only one was group B. When samples from these 26 platelet components with PAS were tested, only one group O donor exceeded the threshold titer. Samples from plasma components with PAS consistently showed a 50 percent decrease in titer compared with the donors' plasma samples. In conclusion, nearly half of the group O donors tested exceeded a titer of 250. Only one apheresis platelet component with PAS exceeded this clinically applied threshold-a 96 percent decrease compared with the number of donor plasma samples without PAS. The implementation of PAS in apheresis platelet components prompted us to revise our component screening process, which then minimized component manipulation of out-of-group platelet transfusions.

Use of Uncrossmatched Erythrocytes in Emergency Bleeding Situations

Transfusion of uncrossmatched erythrocytes is lifesaving in patients who are severely bleeding when crossmatched erythrocytes are unavailable. The hemolysis risk after uncrossmatched erythrocyte administration to appropriate patients is very low.

The Dead Sea needs salt water… massively bleeding patients need whole blood: The evolution of blood product resuscitation

Whole blood, that is blood that is not manufactured into its component red blood cells (RBC) plasma, and platelets (PLT) units, was the mainstay of transfusion for many years until it was discovered that the component parts of a blood donation could be stored under different conditions thereby optimizing the storage length of each product. The use of low anti-A and -B titer group O whole blood (LTOWB) has recently been rediscovered for use in massively bleeding trauma patients. Whole blood has several advantages over conventional component therapy for these patients, including simplifying the logistics of the resuscitation, being more concentrated than whole blood that is reconstituted from conventional components, and providing cold-stored PLTs, amongst other benefits. While randomized controlled trials to determine the efficacy of using LTOWB in the resuscitation of massively bleeding trauma patients are currently underway, retrospective data has shown that massively bleeding recipients of LTOWB with traumatic injury do not have worse outcomes compared to patients who received conventional components and, in some cases, recipients of LTOWB have more favourable outcomes. This paper will describe some of the advantages of using LTOWB and will discuss the emerging evidence for its use in massively bleeding patients.

Activities of the THOR-AABB Working Party

The AABB (formerly the American Association of Blood Banks) is an international authority on transfusion medicine and tissue banking. The Trauma, Hemostasis and Oxygenation Research (THOR) Network is an international multidisciplinary network of civilian and military providers ranging from first responders and medics to critical care physicians and from basic scientists to clinical trialists. The THOR Network's vision is to improve outcomes from traumatic hemorrhagic shock by optimizing the acute phase of resuscitation. Its mission is to develop and implement best practices for prehospital care through to the completion of the acute phase of hemorrhagic shock resuscitation. Thus, there is significant overlap between the missions of these two groups. To this end, the joint THOR-AABB Working Party (WP) was created in the summer of 2016 with a view to improving patient outcomes by the establishment of a formal collaboration between these two groups. The WP has been engaged in many different endeavors, from successfully changing the AABB's standards for the administration of whole blood, to writing commentaries on the safety of unncrossmatched red blood cells and antibody titer methods and thresholds in potentially incompatible plasma products, to hosting a daylong symposium on blood product resuscitation of massively bleeding patients in conjunction with the AABB annual meeting. This review details the activities of the WP and indicates some future activities.

Immunoglobulin M anti-A and anti-B titers in South Texas group O D+ male donors

BACKGROUND

The success of whole blood (WB) in damage control resuscitation on the battlefield has generated interest in its use for civilian trauma. Blood centers must maintain a committed donor pool with low isoagglutinin titers to provide this product. Information regarding isoagglutinin titers in different donor populations will help with targeted recruitment of these donors.

STUDY DESIGN AND METHODS

Sequential O D+ male donors with a history of two or more donations at a fixed site were tested for immunoglobulin (Ig)M anti-A and anti-B using a single titer cutoff of 256. Donors testing negative at this cutoff were considered "low titer" while positive donors were considered "high titer." Age and self-identified race/ethnicity were retrospectively obtained from the blood establishment computer system. Fisher's exact analysis was used for statistical analysis with a p value of less than 0.05 considered significant.

RESULTS

Of 3274 donors, 426 tested as high titer, while 2848 tested as low titer. The data show an association of donor age and prevalence of high titers with older age groups showing a lower prevalence of high titers. In addition, different races/ethnicities have different prevalences of high titers with the Caucasian/white group showing a lower prevalence of high-titer donors versus the Hispanic and undeclared race groups.

CONCLUSION

The prevalence of high-titer IgM anti-A or -B donors varies by age group and race/ethnicity in our data set. This information will provide information on what donor groups to target for collection of low-titer O WB.

Fatal acute hemolytic transfusion reaction due to anti-B from a platelet apheresis unit stored in platelet additive solution

BACKGROUND

Hemolytic transfusion reactions from out-of-group plasma in platelet (PLT) transfusions are uncommon, with most involving passive transfer of anti-A. Only rare reactions have ever been reported due to anti-B.

STUDY DESIGN AND METHODS

An apheresis PLT product was donated by a blood group O male, processed using PLT additive solution, and pathogen reduced. Postreaction recipient testing included an antibody screen using gel technology, a direct antiglobulin test (DAT) using immunoglobulin G and C3, and an eluate against group O and B cells. Postreaction donor testing included measuring anti-B titers in saline, with and without anti-human globulin.

RESULTS

A 60-year-old blood group B patient with relapsed acute myeloid leukemia developed confusion, fever, and hypotension within hours after a blood group O PLT transfusion. The posttransfusion reaction evaluation was remarkable for a positive DAT 3+ for C3; the eluate showed anti-B. Rapid extravascular hemolysis occurred, with a 50% decline in hemoglobin, a high lactate dehydrogenase, and a high bilirubin. She was resuscitated with fluids, blood products, pressors, and oxygen and died of asystole 60 hours later. The donor's anti-B titers were 128 by tube testing at immediate spin and 512 at the anti-human globulin phase. Notably, a group B patient at a different hospital received a split of the same apheresis unit, with no reaction.

CONCLUSION

To our knowledge, this is the first fatality reported from passively transfused anti-B. The fact that one transfusion recipient died whereas another did not have any reported reaction highlights the potential importance of recipient variables in isohemagglutinin-mediated hemolysis.

Acute Hemolytic Transfusion Reaction in Group B Recipient Associated with Group A Apheresis Platelet Donor: Case Report and Literature Review

Acute hemolytic transfusion reaction is a known but rare potential adverse event related to platelet transfusion. Most reported cases of platelet-related hemolytic transfusion reaction have resulted from transfusion of platelets from group O donor to group A recipient. We identified only one prior case report in the literature of hemolytic transfusion reactions resulting from transfusion of apheresis platelets from group A donor to group B recipient. In that case report, two platelet units were obtained from a single donation and transfused into two separate patients. Both patients exhibited acute hemolytic reactions. The donor is reported to have high anti-B titers, as well as report of probiotic use. We report a case of acute hemolytic reaction in group B recipient following transfusion of apheresis platelets from group A donor with high-titer anti-B but unknown status of probiotic use. This case demonstrates that while low, there still exists potential risk for hemolysis from out-of-group A plasma transfusion.

Safety profile of uncrossmatched, cold-stored, low-titer, group O+ whole blood in civilian trauma patients

BACKGROUND

The use of cold-stored low-titer group O whole blood (LTOWB) for civilian trauma patients is gaining popularity. However, hemolysis might occur among non-group O recipients. This study evaluated the serologic safety of transfusing up to 4 units of LTOWB.

STUDY DESIGN AND METHODS

Hypotensive male and at least 50-year-old female trauma patients who received leukoreduced, uncrossmatched, group O+, low-titer (<50 anti-A and anti-B), platelet-replete whole blood during initial resuscitation were included in this prospective, observational study. Biochemical markers of hemolysis were measured on the day of LTOWB receipt (Day 0) and over the next 2 days. Blood product administration in the first 24 hours of admission and reported transfusion-associated adverse events were also reviewed.

RESULTS

There were 102 non-group O and 70 group O recipients of 1 to 4 LTOWB units analyzed. The non-group O recipients received a median volume of 600 mL (range, 300-4100 mL) of ABO-incompatible plasma, including the contribution from the LTOWB units. There were no significant differences in median haptoglobin, lactate dehydrogenase, total bilirubin, creatinine, or potassium levels at any time point between the non-group O and group O recipients. There were also no differences in these markers between the subset of 23 non-group O and 14 group O recipients who received 3 or 4 LTOWB units. No transfusion-associated adverse events were reported.

CONCLUSIONS

Administration of up to 4 units of LTOWB in civilian trauma resuscitation was not associated with clinical or biochemical evidence of hemolysis. Six units per trauma patient are now permitted at these institutions.

Anti-D Alloimmunization after RhD-Positive Platelet Transfusion in RhD-Negative Women under 55 Years Diagnosed with Acute Leukemia: Results of a Retrospective Study

Background

Anti-D alloimmunization can occur when platelets from RhD-positive donors are transfused to RhD-negative patients, due to red blood cell residues in the platelet concentrates.

Methods

Our objective was to analyze the anti-D alloimmunization rate in a selected group of women under 55 years of age diagnosed with acute leukemia over an 18-year period. We focused the analysis on RhD-negative patients who received RhD-positive platelet transfusions.

Results

From January 1998 to October 2016, 382 women under 55 years were diagnosed with acute leukemia. A total of 56 patients were RhD-negative, and 48 (85.7%) received RhD-positive platelets. The median number of platelet concentrates transfused per patient was 23, and 48% of all platelet transfusions were RhD-positive. The 48 RhD-negative patients received a total of 949 RhD-positive platelet concentrates. Two patients developed anti-D: a 36-year-old woman with M3 acute myeloblastic leukemia and a 52-year-old patient with a secondary acute myeloblastic leukemia.

Conclusion

We conclude that there is a need for agreement in the transfusion guidelines on the recommendation of anti-D alloimmunization prophylaxis. We suggest a possible benefit in favor of anti-D prophylaxis in childbearing women with acute leukemia.

Safety of the use of group A plasma in trauma: the STAT study

BACKGROUND

Use of universally ABO-compatible group AB plasma for trauma resuscitation can be challenging due to supply limitations. Many centers are now using group A plasma during the initial resuscitation of traumatically injured patients. This study was undertaken to evaluate the impact of this practice on mortality and hospital length of stay (LOS).

STUDY DESIGN AND METHODS

Seventeen trauma centers using group A plasma in trauma patients of unknown ABO group participated in this study. Eligible patients were group A, B, and AB trauma patients who received at least 1 unit of group A plasma. Data collected included patient sex, age, mechanism of injury, Trauma Injury Severity Score (TRISS) probability of survival, and number of blood products transfused. The main outcome of this study was in-hospital mortality differences between group B and AB patients compared to group A patients. Data on early mortality (≤24 hr) and hospital LOS were also collected.

RESULTS

There were 354 B and AB patients and 809 A patients. The two study groups were comparable in terms of age, sex, TRISS probability of survival, and total number of blood products transfused. The use of group A plasma during the initial resuscitation of traumatically injured patients of unknown ABO group was not associated with increased in-hospital mortality, early mortality, or hospital LOS for group B and AB patients compared to group A patients.

CONCLUSION

These results support the practice of issuing thawed group A plasma for the initial resuscitation of trauma patients of unknown ABO group.

Novel TPO receptor agonist TA-316 contributes to platelet biogenesis from human iPS cells

Signaling by thrombopoietin (TPO) in complex with its receptor, c-MPL, is critical for hematopoietic stem cell (HSC) homeostasis and platelet generation. Here we show that TA-316, a novel chemically synthesized c-MPL agonist (CMA), is useful for ex vivo platelet generation from human-induced pluripotent stem (iPS) cell-derived immortalized megakaryocyte progenitor cell lines (imMKCLs). Moreover, the generation is clinically applicable, because self-renewal expansion and platelet release is tightly controllable. TA-316 but not eltrombopag, another CMA, promoted both the self-renewal and maturation of imMKCLs, leading to more than a twofold higher platelet production than that achieved with recombinant human TPO (rhTPO). Interestingly, TA-316 seemed to favor MK-biased differentiation from bone marrow CD34⁺ HSC/progenitors and imMKCLs through the upregulation of vascular endothelial growth factor A and fibroblast growth factor 2. This result suggests TA-316 could facilitate the development of an efficient and useful system to expand platelets from imMKCLs.

Effectiveness of Pooled Platelet Transfusion in Concordant and Discordant Groups among Dengue Patients

INTRODUCTION

Dengue affects more than 50 million people per year and is one of the most common causes of severe thrombocytopaenia. Thrombocytopaenia is a common complication of dengue and other viral fevers apart from malaria, typhoid, leptospirosis, leukaemia and megaloblastic anaemia. A platelet count of <20,000/μl is characteristically seen in dengue haemorrhagic fever and dengue fever. It results from immune complex mediated platelet destruction or bone marrow suppression. Severe thrombocytopaenia <10,000/μl is one of the indications for prophylactic platelet transfusion therapy to prevent haemorrhage.

AIM

To evaluate the effectiveness of transfusion of ABO compatible and ABO incompatible pooled platelet units in severe thrombocytopaenia cases.

MATERIALS AND METHODS

In this study ABO compatible and incompatible pooled platelet units were transfused to serologically confirmed dengue cases having thrombocytopaenia with or without bleeding manifestations. Each of the adult patients received 4-6 units of pooled platelet concentrates prepared from random donor whole blood suspended in plasma for severe thrombocytopaenia. Pre and post transfusion platelet counts were compared. Children aged less than 12 years, pregnant women and patients with splenomegaly those on ayurvedic and homeopathic therapy, recipients of packed red cells on the same day of platelet transfusion and recipients of multiple platelet transfusions within 24 hours were excluded from the study.

RESULTS

The median post transfusion platelet increments (PPI) and corrected count increments (CCI) at 4hour post transfusion were 25,000/μL (5,000-80,000/μL) and 18,000/μL (range 8,000/μL- 47,500/μL) respectively among the responders. Median PPI and CCI at 24 hours were 45,000/μL and 28,863/μL among the responders. The median CCI at 4 hour post transfusion among the non-responders was 850/μL and at 24hours was 1,425/μL. At 24 hours responders showed significantly higher PPI as compared to non responders. The average platelets transfused were 4units in case of responders and 8 units in case of non-responders.

CONCLUSION

ABO identical and compatible pooled platelet transfusions were more successful in increasing the post transfusion platelet counts as compared to ABO incompatible pooled platelets.

Improving platelet transfusion safety: biomedical and technical considerations

Platelet concentrates account for near 10% of all labile blood components but are responsible for more than 25% of the reported adverse events. Besides factors related to patients themselves, who may be particularly at risk of side effects because of their underlying illness, there are aspects of platelet collection and storage that predispose to adverse events. Platelets for transfusion are strongly activated by collection through disposal equipment, which can stress the cells, and by preservation at 22 °C with rotation or rocking, which likewise leads to platelet activation, perhaps more so than storage at 4 °C. Lastly, platelets constitutively possess a very large number of bioactive components that may elicit pro-inflammatory reactions when infused into a patient. This review aims to describe approaches that may be crucial to minimising side effects while optimising safety and quality. We suggest that platelet transfusion is complex, in part because of the complexity of the "material" itself: platelets are highly versatile cells and the transfusion process adds a myriad of variables that present many challenges for preserving basal platelet function and preventing dysfunctional activation of the platelets. The review also presents information showing--after years of exhaustive haemovigilance--that whole blood buffy coat pooled platelet components are extremely safe compared to the gold standard (i.e. apheresis platelet components), both in terms of acquired infections and of immunological/inflammatory hazards.

A possible new paradigm? A survey-based assessment of the use of thawed group A plasma for trauma resuscitation in the United States

BACKGROUND

Although evidence supporting this practice is limited, some centers use thawed group A plasma for the initial resuscitation of trauma patients.

STUDY DESIGN AND METHODS

To better understand the current use of plasma in trauma resuscitation, a survey was developed, validated, and distributed via e-mail to 121 American trauma centers.

RESULTS

A total of 61 responses were received. Most were from Level 1 trauma centers (56/61, 92%) in urban settings (47/61, 77%). Virtually all centers reported maintaining A thawed plasma inventory (59/61, 97%). Among the 56 Level 1 trauma center respondents, most keep thawed A immediately available (49/56, 88%) and many use group A plasma for trauma recipients of unknown ABO group (34/49, 69%). Half of the surveyed centers implemented this practice within the past year. The majority do not limit the amount of A plasma that can be administered to a patients of unknown ABO group (21/34, 62%), and most do not titer for anti-B (27/34, 79%).

CONCLUSION

The majority of Level 1 trauma centers maintain thawed plasma inventories and use group A plasma for trauma recipients of unknown ABO group. Most centers do not limit the amount of group A plasma used in this situation or titer the anti-B.

Transfusion of ABO non-identical platelets does not influence the clinical outcome of patients undergoing autologous haematopoietic stem cell transplantation

BACKGROUND

There are ABO antigens on the surface of platelets, but whether ABO compatible platelets are necessary for transfusions is a matter of ongoing debate. We retrospectively reviewed the ABO matching of platelet transfusions in a subset of patients undergoing autologous haematopoietic progenitor cell transplantation during a 14-year period. Our aim was to analyse the characteristics and outcomes of patients who received platelet transfusions that were or were not ABO identical.

MATERIAL AND METHODS

We analysed 529 consecutive patients with various haematological and non-haematological diseases who underwent 553 autologous progenitor stem cell transplants at the University Hospital la Fe between January 2000 and December 2013. We retrospectively analysed and compared transfusion and clinical outcomes of patients according to the ABO match of the platelet transfusions received. The period analysed was the time from transplantation until discharge.

RESULTS

The patients received a total of 2,772 platelet concentrates, of which 2,053 (74.0%) were ABO identical and 719 (26.0%) ABO non-identical; of these latter 309 were compatible and 410 incompatible with the patients' plasma. Considering all transplants, 36 (6.5%) did not require any platelet transfusions, while in 246 (44.5%) cases, the patients were exclusively transfused with ABO identical platelets and in 47 (8.5%) cases they received only ABO non-identical platelet transfusions. The group of patients who received both ABO identical and ABO non-identical platelet transfusions had higher transfusion needs and worse clinical outcomes compared to patients who received only ABO identical or ABO non-identical platelets.

DISCUSSION

In our hospital, patients undergoing autologous haematopoietic stem cell transplantation who received ABO identical or ABO non-identical platelet transfusions had similar transfusion and clinical outcomes. The isolated fact of receiving ABO non-identical platelets did not influence morbidity or survival.

Low frequency of anti-D alloimmunization following D+ platelet transfusion: the Anti-D Alloimmunization after D-incompatible Platelet Transfusions (ADAPT) study

The reported frequency of D alloimmunization in D- recipients after transfusion of D+ platelets varies. This study was designed to determine the frequency of D alloimmunization, previously reported to be an average of 5 ± 2%. A primary anti-D immune response was defined as the detection of anti-D ≥ 28 d following the first D+ platelet transfusion. Data were collected on 485 D- recipients of D+ platelets in 11 centres between 2010 and 2012. Their median age was 60 (range 2-100) years. Diagnoses included: haematological (203/485, 42%), oncological (64/485, 13%) and other diseases (218/485, 45%). Only 7/485 (1·44%; 95% CI 0·58-2·97%) recipients had a primary anti-D response after a median serological follow-up of 77 d (range: 28-2111). There were no statistically significant differences between the primary anti-D formers and the other patients, in terms of gender, age, receipt of immunosuppressive therapy, proportion of patients with haematological/oncological diseases, transfusion of whole blood-derived or apheresis platelets or both, and total number of transfused platelet products. This is the largest study with the longest follow-up of D alloimmunization following D+ platelet transfusion. The low frequency of D alloimmunization should be considered when deciding whether to administer Rh Immune Globulin to D- males and D- females without childbearing potential after transfusion of D+ platelets.

[Platelet transfusion and immunization anti-Rh1: implication for immunoprophylaxis]

Rhesus (Rh) antigens are not expressed on platelets but residual red cells carry the risk of anti-D iso-immunization in transfusion recipients of platelet concentrates (PC). The main theoretical risk associated with this reaction relates to female subjects due to potential obstetrical situations of maternal-foetal Rh incompatibility. Isogroup PC transfusion in this system is therefore advised. However, logistical constraints impose frequent Rh-incompatible transfusions that require the recommendation of anti-Rh immunoglobulin in a girl of childbearing age in this situation. This recommendation, already restricted to a group of patients deserves to be questioned over a decade after being issued. Data from published reports are difficult to interpret because of the heterogeneity of the few series (CP type, immune status, timing of biological tests) but the current techniques for preparing products and most common use of CP apheresis limited the risk of immunization. Moreover, platelet transfusions are particularly relevant to immunocompromised populations which, to what extent (heavy chemotherapy and/or hematopoietic stem cells recipients) seems to be protected from this risk. It is noteworthy that the clinical consequences that may be expected from such immunization are not reported. Although some authors emphasize significant isoimmunization rates (maximum 19%), the heterogeneous conditions and the lack of evidence of clinical consequence suggest evaluating the recommendations or revising them towards more targeted indications of seroprophylaxis.