PLTs of Blood Group A1donors express increased surface A antigen owing to apheresis and prolonged storage

Transfusion outcomes and clinical safety of ABO-nonidentical platelets transfusion: A systematic review and meta-analysis

BACKGROUND

ABO-nonidentical platelets transfusion has been frequently employed to address clinical platelets insufficiencies. The significance of ABO compatibility for platelets transfusion is not clearly defined. This study is aimed to explore the transfusion outcomes and clinical safety of ABO-nonidentical platelets transfusion.

STUDY DESIGN AND METHODS

A systematic articles search was performed for eligible studies published up to November 30, 2023 through the PubMed, Embase, Cochrane library, Chinese National Knowledge Infrastructure database, Wanfang database and SinMed. Meta-analysis Of Observational Studies in Epidemiology study guidelines for observational studies and Newcastle Ottawa bias scale were implemented to assess studies. Meta-analysis was performed using Manager 5.3. This study is registered with PROSPERO, number CRD42023417824.

RESULTS

A total of 11 retrospective cohort studies and 7 prospective cohort studies with a sample size of 104,359 platelets transfusions were included. There was significant difference in transfusion effectiveness between the ABO-identical and ABO-nonidentical platelets transfusions (RR 1.20, 95 % CI 1.11-1.38, P < 0.00001, I2 = 21 %), also the ABO-identical platelets transfusions showed more platelets increment than ABO-nonidentical ones, but it was not statistically significant (MD 0.34, 95 % CI - 0.01 to 0.70, P = 0.06, I2 = 0 %). Allergy and fever occurred more in ABO-nonidentical platelets transfusions in terms of adverse reactions (RR 0.63, 95 % CI 0.41-0.96, P = 0.03, I2 = 0 %; RR 0.59, 95 % CI 0.37-0.94, P = 0.03, I2 = 31 %). When it comes to the mortality, the ABO-identical platelets transfusions did not statistically improve survival in patients who received multiple platelets transfusions (RR 0.77, 95 % CI 0.72-0.83, P = 0.17, I2 = 38 %) and who only received less than 3 transfusions (RR 0.74, 95 % CI 0.52-1.06, P = 0.10, I2 = 47 %) compared with the ABO-nonidentical platelets transfusions.

CONCLUSION

In comparison to ABO-identical platelets transfusions, nonidentical platelets transfusions exhibited lower transfusion efficacy. However, the clinical safety between these two groups was similar, which indicated that ABO-nonidentical transfusions are acceptable, albeit inferior to ABO-identical ones.

ABO Incompatibility between the Mother and Fetus Does Not Protect against Anti-Human Platelet Antigen-1a Immunization by Pregnancy

(1) Background: ABO blood group incompatibility between the mother and fetus protects against anti-D immunization by pregnancy. The possible role of ABO incompatibility in protecting against anti-human platelet antigen-1a immunization is unclear. (2) Methods: This study retrospectively screened 817 families (mother-father-neonate trios) of suspected fetal and neonatal alloimmune thrombocytopenia for inclusion. ABO genotypes were determined in 118 mother-child pairs with confirmed alloimmune thrombocytopenia due to anti-HPA-1a antibodies, and 522 mother-child pairs served as the control group. The expression of blood group antigen A on platelets was determined in 199 consecutive newborns by flow cytometry and compared with adult controls. (3) Results: ABO incompatibility between mother and fetus did not protect against anti-human platelet antigen-1a immunization by pregnancy. ABO blood groups of mothers and/or fetuses were not associated with the severity of fetal and neonatal alloimmune thrombocytopenia. The expression pattern of blood group A antigens on the platelets of newborns mirrored that of adults, albeit on a lower level. Blood group A antigen was detected on a subpopulation of neonatal platelets, and some newborns revealed high platelet expression of A determinants on all platelets (type II high-expressers). (4) Conclusion: The lack of a protective effect of ABO incompatibility between mother and fetus against anti-human platelet antigen-1a immunization by pregnancy may indicate that fetal platelets are not the cellular source by which the mother is immunized.

A Prospective Observational Study To Compare Transfusion Outcomes In Abo Identical Versus Abo Non-Identical Single Donor Platelet Concentrates: An Experience From A Tertiary Healthcare Center In India

ABO incompatible single donor platelet concentrates (SDPC) have a concern about unsatisfactory increments as well as possibility of hemolytic transfusion reaction. But from Indian population no study has commented on the clinical and laboratory outcome of ABO mismatched platelet transfusion. The aim of study was to compare transfusion outcomes in ABO identical versus ABO non-identical single donor platelet concentrates. In this prospective observational study, 400 SDPC transfusions among different patients were included. In group A (n = 200), ABO identical SDPC transfusions and in group B (n = 200) ABO non-identical SDPC transfusions were added. Corrective count increment (CCI), absolute count increment (ACI), percent platelet recovery (PPR) were calculated and incidents of hemolytic transfusion reactions were noted. In group A mean ± SD of ACI, CCI and PPR were as 30.78 ± 12.51, 15.10 ± 6.677, 39948.9 ± 20099.392. In group B, mean ± SD of ACI, CCI and PPR were - 25.4 ± 15.65, 12.509 ± 5.906, 33559.2 ± 22150.304. And when CCI, ACI, PPR were compared with group A and group B, statistically significant differences were noted (p <0.05). There was statistically significant difference in CCI, ACI and PPR in oncology patients and other prophylactic recipients except patients with dengue and other infectious disease. But there was no hemolytic transfusion reaction noted in any group. Our study clearly establish the potential benefits of ABO-identical PLT transfusion. It also points out that in emergency conditions or when there is a paucity in inventory, ABO non-identical SDPC transfusion may be lifesaving and clinically significant.

Current trends in platelet transfusions practice: The role of ABO-RhD and human leukocyte antigen incompatibility

Platelet transfusions have contributed to the revolutionary modern treatment of hypoproliferative thrombocytopenia. Despite the long-term application of platelet transfusion in therapeutics, all aspects of their optimal use (i.e., in cases of ABO and/or Rh (D incompatibility) have not been definitively determined yet. We reviewed the available data on transfusion practices and outcome in ABO and RhD incompatibility and platelet refractoriness due to anti-human leukocyte antigen (HLA) antibodies. Transfusion of platelets with major ABO-incompatibility is related to reduced posttransfusion platelet (PLT) count increments, compared to ABO-identical and minor, but still are equally effective in preventing clinical bleeding. ABO-minor incompatible transfusions pose the risk of an acute hemolytic reaction of the recipient that is not always related to high anti-A, B donor titers. ABO-identical PLT transfusion seems to be the most effective and safest therapeutic strategy. Exclusive ABO-identical platelet transfusion policy could be feasible, but alternative approaches could facilitate platelet inventory management. Transfusion of platelets from RhD positive donors to RhD negative patients is considered to be effective and safe though is associated with low rate of anti-D alloimmunization due to contaminating red blood cells. The prevention of D alloimmunization is recommended only for women of childbearing age. HLA alloimmunization is a major cause of platelet refractoriness. Managing patients with refractoriness with cross-matched or HLA-matched platelets is the current practice although data are still lacking for the efficacy of this practice in terms of clinical outcome. Leukoreduction contributes to the reduction of both HLA and anti-D alloimmunization.

The Blood Group A Genotype Determines the Level of Expression of the Blood Group A on Platelets But Not the Anti-B Isotiter

BACKGROUND

The extent of expression of the blood group A on platelets is controversial. Further, the relation between platelets' blood group A expression and the titers of isoagglutinins has not been thoroughly investigated, so far.

METHODS

We evaluated the relation between the genotype with platelets' blood group A and H expression estimated by flow cytometry and the titers of isoagglutinins.

RESULTS

The A expression varied between genotypes and within genotypes. However, the expression in A1 was stronger than in all other genotypes (p < 0.0001). An overlap of expression levels was apparent between homozygous A1A1 and heterozygous A1 individuals. Still, The A1A1 genotype is associated with a particularly high antigen expression (p = 0.009). Platelets' A expression in A2 versus blood group O donors was also significant (p = 0.007), but there was again an overlap of expression. The secretor status had only little influence on the expression (p = 0.18). Also, isoagglutinin titers were not associated with genotypes.

CONCLUSION

To distinguish between A1 and A2 donors may reduce incompatible platelet transfusions and therefore be favorable on platelet transfusion increment. Clinical data are needed to support this notion.

ABO Blood Group as a Model for Platelet Glycan Modification in Arterial Thrombosis

ABO blood groups have long been associated with cardiovascular disease, thrombosis, and acute coronary syndromes. Many studies over the years have shown type O blood group to be associated with lower risk of cardiovascular disease than non-type O blood groups. However, the mechanisms underlying this association remain unclear. Although ABO blood group is associated with variations in concentrations of circulating von Willebrand Factor and other endothelial cell adhesion molecules, ABO antigens are also present on several platelet surface glycoproteins and glycosphingolipids. As we highlight in this platelet-centric review, these glycomic modifications may affect platelet function in arterial thrombosis. More broadly, improving our understanding of the role of platelet glycan modifications in acute coronary syndromes may inform future diagnostics and therapeutics for cardiovascular diseases.

Prevalence, serologic and genetic studies of high expressers of the blood group A antigen on platelets*

OBJECTIVE/AIM

The aim of this study is to describe the distribution of the platelet blood group A antigenicity in Euro-Brazilians (EUBs) and Afro-Brazilians (AFBs).

BACKGROUND

A small but significant proportion of individuals express high levels of A or B antigen on their platelets corresponding to the erythrocyte ABO group. The mechanism of increased antigen expression has not been elucidated.

MATERIAL/METHODS

A cohort of 241 blood group A donors was analysed by flow cytometry. Although mean fluorescence intensity (MFI) is a typical continuous variable, platelets were screened and divided into two categories: low expressers (LEs) and high expressers (HEs). A three-generation family was investigated looking for an inheritance mechanism.

RESULTS

The prevalence of the HE platelet phenotype among group A(1) donors was 2%. The mean of MFI on platelets of A(1) subgroup of EUBs differs from that of AFBs (P = 0·0115), whereas the frequency of the HE phenotype was similar between them (P = 0·5251). A significant difference was found between sexes (P = 0·0039). Whereas the serum glycosyltransferase from HE family members converted significantly more H antigen on group O erythrocytes into A antigens compared with that in LE serum, their ABO, FUT1 and FUT2 genes were consensus. The theoretically favourable, transcriptionally four-repeat ABO enhancer was not observed.

CONCLUSION

The occurrence of HE in several members suggests familial aggregation. Indeed, in repeated measures, stability of the MFI values is suggesting an inherited condition. Factors outside the ABO locus might be responsible for the HE phenotype. Whether the real mechanism of inheritance is either of a polygenic or of a discrete Mendelian nature remains to be elucidated.

ABO histo-blood group system-incompatible allografting

Most of the 29 blood group systems known today are not restricted to erythroid tissues hence their more recent identification as histo-blood group systems. Beyond the uncontested importance of the HLA system in human allograft survival, some of the histo-blood group systems might increasingly become recognised to play a role in graft-host interaction and peritransplant transfusion therapy. At least the ABO histo-blood group system has drawn a lot of interest since both, elective ABO-mismatch with living kidney donor/recipient pairs and infant heart recipients have been described as radical, but effective treatments of end-stage organ dysfunction. More recently, at least in part successful efforts to overcome unintentional ABO-mismatched lung and heart grafts spark interest in more precisely avoiding hyperacute transplant rejection due to complement-activating anti-A/B antibodies of the recipients. Such options as to prepare the recipient with plasma exchange and following him up with polyspecific intravenous immunoglobulins, monoclonal antibodies and targeted immunosuppression using mycophenolate, rabbit antithymocyte globulin and anti-CD20 antibody rituximab are bound to efficiently remove anti-A/B antibodies and apparently inhibit their resynthesis. The present contribution overviews recently acquired knowledge on the ABO histo blood group system and the role it plays in solid organ transplantation leant against a patient observed at our institution.

Determinants of ABH expression on human blood platelets

Platelets express ABH antigens, which can adversely effect platelet transfusion recovery and survival in ABH-incompatible recipients. To date, there has been no large, comprehensive study comparing specific donor factors with ABH expression on platelet membranes and glycoconjugates. We studied ABH expression in 166 group A apheresis platelet donors by flow cytometry, Western blotting, and thin layer chromatography relative to donor age, sex, A1/A2 subgroup, and Lewis phenotype. Overall, A antigen on platelet membranes, glycoproteins, and glycosphingolipids was linked to an A1 red blood cell (RBC) phenotype. Among A1 donors, platelet ABH varied significantly between donors (0%-87%). Intradonor variability, however, was minimal, suggesting that platelet ABH expression is a stable, donor-specific characteristic, with 5% of A1 donors typing as either ABH high- or low-expressers. Group A2 donors, in contrast, possessed a Bombay-like phenotype, lacking both A and H antigens. Unlike RBCs, ABH expression on platelets may be determined primarily by H-glycosyltransferase (FUT1) activity. Identification of A2 and A1 low expressers may increase the availability and selection of crossmatched and HLA-matched platelets. Platelets from group A2 may also be a superior product for patients undergoing A/O major mismatch allogeneic progenitor cell transplantation.