OBJECTIVE: ABO blood group mismatch between the donor and the recipient can affect the success of the transplant as well as problems with the red blood cells during allogeneic haematopoietic cell transplantation (HCT). However, the impact of the Rhesus (Rh) D mismatch on transplant outcomes in allogeneic HCT has been poorly elucidated.
METHODS: We retrospectively evaluated the impact of the RhD mismatch on post-transplant outcomes in 64,923 patients who underwent allogeneic HCT between 2000 and 2021 using a Japanese registry database.
RESULTS: Out of the whole group, 64,293, 322, 270 and 38 HCTs were done when the recipient or donor was RhD-mismatched with (+/+), (-/+), (+/-) or (-/-) combinations. The difference in RhD between recipient/donor (-/+), (+/-) and (-/-) did not affect haematopoietic recovery, acute and chronic graft-versus-host disease (GVHD), overall survival (OS), non-relapse mortality (NRM) or relapse when RhD (+/+) was used as the reference group in multivariate analysis.
CONCLUSIONS: Our registry-based study demonstrated that RhD mismatch between recipient and donor did not significantly impact haematopoietic recovery, GVHD, OS, NRM or relapse after allogeneic HCT. These data suggest that RhD mismatches may not need to be avoided for recipient and donor combinations in allogeneic HCT.

BACKGROUND The use of ABO-incompatible liver transplants (ABO-ILTs) from deceased donors has become more common due to the shortage of available donor livers and increased transplant waiting times. This retrospective study from a national transplant center at Helsinki University Hospital, Finland, aimed to assess the long-term outcomes of ABO-incompatible deceased donor pediatric liver transplants between 1987 and 2022. MATERIAL AND METHODS Sixteen (9.5%) of the 169 pediatric liver transplantations were ABO-ILTs. The median age at transplantation was 5.0 (0.5-15.4) years. Reasons for ABO-ILTs were acute liver failure (18.75%), malignancy (12.5%), small body size and long waiting time (25%), and other reasons (43.75%). The median post-transplant follow-up time was 147 (0.72-353) months. Patient and graft survival and occurrence of surgical complications were compared to ABO-identical transplants, and anti-ABO antibody titers were analyzed. RESULTS The 1-, 3-, and 5-year patient survivals were comparable between the ABO-I and ABO-compatible groups, being 81.3%, 73.9%, and 73.9% (ABO-I) and 87.5%, 82.5%, 77.9% (ABO-compatible), respectively. Three patients with ABO-ILTs died of sepsis and multiorgan failure during the first 3 months after transplantation. The occurrence of biliary complications and early vascular thrombosis (<30 days after transplantation) did not differ significantly between recipients with an ABO-ILT vs ABO-compatible liver graft. CONCLUSIONS The findings from this study support findings from previous studies that outcomes after ABO-incompatible liver transplants in children were comparable to outcomes from ABO-identical liver transplants.

OBJECTIVE: The current study aimed to examine the incidence of perioperative infections and graft viability in ABO-compatible and ABO-incompatible renal transplant recipients.
METHODS: We included 643 living donor renal transplant recipients registered in the Michinoku Renal Transplant Network from 1998 to 2021. Patients were divided into the ABO-compatible and ABO-incompatible kidney transplantation groups. We compared the characteristics of the two groups and evaluated the incidence of postoperative viral infections (cytomegalovirus and BK virus), graft loss-free survival, and overall survival between the two groups.
RESULTS: Of 643 patients, 485 (75%) and 158 (25%) were ABO-compatible and ABO-incompatible renal transplant recipients, respectively. Postoperative viral infections, rituximab use, and plasma exchange were significantly more common in ABO-incompatible than in ABO-compatible transplant recipients. However, there were no significant differences in terms of other background characteristics. The ABO-incompatible group was more likely to develop viral infections than the ABO-compatible group. Graft loss-free survival and overall survival did not significantly differ between the two groups. According to the multivariate Cox regression analysis, ABO compatibility was not significantly associated with graft loss-free survival and overall survival.
CONCLUSIONS: Although the incidence of postoperative viral infections in ABO-incompatible renal transplant recipients increased, there was no significant difference in terms of rejection events, graft loss-free survival, and overall survival.

Neutralizing capacity measurement (NCM) of soluble ABH substances (SAS) in plasma was assessed to guide the selection of the appropriate ABO group of fresh-frozen plasma (FFP) for plasma exchange (PE) in blood group O recipients with ABO-incompatible transplantations. Neutralizing capacity was assessed by measuring anti-A and/or anti-B titers in samples comprising one unit of O FFP and 10 O EDTA plasma samples and subtracting the binary logarithm of the titer in each group with a saline dilution. Ten EDTA plasma samples with Lewis b (Leb) antigen positivity and 10 sets of pooled FFP from each blood group were used as diluents. In O FFP, the NCM values (mean±SD) were 3.4±0.52 (2.6±0.52) and 2.6±0.52 (1.5±0.3) in B and AB for IgM (total antibody) anti-B (both P<0.001), and in the 10 O EDTA plasma samples, they were 3.9±0.88 (3.1±0.88) and 3.2±0.79 (2.4±0.97) for IgM (P=0.0013) and total anti-B (P=0.025), respectively. In vitro analysis revealed that B FFP is more effective than AB FFP in reducing IgM and total anti-B antibody titers in O recipients, regardless of Leb antigen positivity.

BACKGROUND: Hemolytic disease of the newborn (HDN) results in the decreased lifespan of the red cells. HDN related to ABO incompatibility is mostly unnoticed because routine screening is not being done. This study was done to assess the prevalence of ABO-HDN and to compare different immunohematological tests. Methods-In this study 213 O group mothers and the 122 ABO-incompatible newborns born to them were included. Quantifying the maternal IgG anti-A/anti-B antibody titer was done by Conventional Tube Technique (CTT) using Dithiothreitol (DTT) pretreated maternal serum. Hemolysin test was performed on the mothers having titer > 256. These cases were followed up and, after delivery, were monitored for ABO HDN, along with direct antiglobulin testing and elution studies. The prevalence of ABO-HDN was calculated, and the different diagnostic parameters of the tests were calculated. Results- The prevalence of ABO-HDN in our population was estimated to be 1.7%, 6.1% & 10.6% in our population, O group mothers, and O group mothers with ABOincompatible newborns, respectively. Maternal titer≥ 512 strongly correlated with ABOHDN. DAT positivity is a good predictor of ABO-HDN, especially using sensitive techniques. Maternal IgG titers have the highest sensitivity & Negative Predictive Value, while DAT has the highest specificity & Positive Predictive Value. Conclusion - Maternal ABO antibody titration may be advocated in the centers to identify high-risk groups. It can advocate institutional delivery and dedicated follow-up of newborns with ABO-HDN. Blood grouping & DAT may be performed in all newborns born to O blood group to identify high-risk cases.

BACKGROUND: There is no robust evidence-based data for ABO-incompatible kidney transplantation (ABOiKT) from emerging countries.
METHODS: Data from 1759 living donor ABOiKT and 33 157 ABO-compatible kidney transplantations (ABOcKT) performed in India between March 5, 2011, and July 2, 2022, were included in this retrospective, multicenter (n = 25) study. The primary outcomes included management protocols, mortality, graft loss, and biopsy-proven acute rejection (BPAR).
RESULTS: Protocol included rituximab 100 (232 [13.18%]), 200 (877 [49.85%]), and 500 mg (569 [32.34%]); immunoadsorption (IA) (145 [8.24%]), IVIG (663 [37.69%]), and no induction 200 (11.37%). Mortality, graft loss, and BPAR were reported in 167 (9.49%), 136 (7.73%), and 228 (12.96%) patients, respectively, over a median follow-up of 36.3 mo. In cox proportional hazard model, mortality was higher with IA (hazard ratio [HR]: 2.53 [1.62-3.97]; P  < 0.001), BPAR (HR: 1.83 [1.25-2.69]; P  = 0.0020), and graft loss (HR: 1.66 [1.05-2.64]; P  = 0.0310); improved graft survival was associated with IVIG (HR: 0.44 [0.26-0.72]; P  = 0.0010); higher BPAR was reported with conventional tube method (HR: 3.22 [1.9-5.46]; P  < 0.0001) and IA use (HR: 2 [1.37-2.92]; P  < 0.0001), whereas lower BPAR was reported in the prepandemic era (HR: 0.61 [0.43-0.88]; P  = 0.008). Primary outcomes were not associated with rituximab dosing or high preconditioning/presurgery anti-A/anti-B titers. Incidence of overall infection 306 (17.39%), cytomegalovirus 66 (3.75%), and BK virus polyoma virus 20 (1.13%) was low. In unmatched univariate analysis, the outcomes between ABOiKT and ABOcKT were comparable.
CONCLUSIONS: Our largest multicenter study on ABOiKT provides insights into various protocols and management strategies with results comparable to those of ABOcKT.

The clinical outcomes of ABO-incompatible (ABOi) kidney transplantation have improved with the introduction of desensitization therapy with rituximab. However, rituximab prevents not only antibody-mediated rejection (AMR) but also increases the risk of adverse events, such as infection. For ABOi kidney transplantation in patients with low anti-A/B antibody titers, we previously used a rituximab-free desensitization protocol and then initiated a single dose of 100 mg rituximab in 2016. We retrospectively compared the outcomes of ABOi kidney transplantation in patients with low anti-A/B antibody titers before and after the introduction of rituximab.
ABOi kidney transplantations (n = 142) in patients with low anti-A/B antibody titers between 2007 and 2021 were included. Patients were divided into two groups (with and without rituximab) for desensitization. The primary outcomes were the incidence of acute AMR and infection.
Sixty-six patients were desensitized without rituximab (rituximab-free group), and 76 were pretreated with 100 mg rituximab (rituximab group) before transplantation. The incidence of acute AMR was significantly lower in the rituximab group than in the rituximab-free group (.0% [0/76] vs. 7.6% [5/66], respectively; p = .047). Post-transplantation anti-A/B antibody titers were also lower in the rituximab group than in the rituximab-free group. There was no significant difference in the incidence of adverse events, including infections, between the two groups.
In ABOi kidney transplantation patients with low anti-A/B antibody titers, the desensitization protocol with a single dose of 100 mg rituximab was effective in preventing acute AMR without increasing the risk of other adverse events.

Acute hemolytic transfusion reactions (AHTRs) are feared complications of packed red blood cell (PRBC) transfusions. This study aimed to investigate the clinical consequences of isolated enzyme-phase crossmatch-incompatible PRBC transfusions by clinically observing all events during the study period at a single institution with the primary goal of detecting AHTRs. Ninety-four transfusions of interest were administered during the study period. Laboratory investigations were adequate in 73 episodes, where no AHTR developed and a mean hemoglobin concentration rise of 1.1 g/dL was documented. Three transfusions were terminated prematurely; however, further investigations ruled out AHTR. The remaining 21 transfusions were also completed uneventfully without noteworthy clinical deterioration. This study’s results provide clinical validation to omit pretransfusion screening with enzyme-phase crossmatch and document the safety and short-term efficacy of isolated enzyme-phase incompatible transfusions. The findings may encourage future clinical research to better understand the long-term efficacy of such transfusions, which may be valuable for transfusion-dependent patients.
Eritrosit süspansiyonu (ES) transfüzyonlarının korkulan yan etkilerinden birisi akut hemolitik transfüzyon reaksiyonlarıdır (AHTR). Çalışma, izole enzim-fazı çapraz karşılaştırma testi uyumsuz olan ES transfüzyonlarını klinik olarak gözlemleyerek, bu transfüzyonların klinik sonuçlarını araştırmaktadır. Birincil sonlanım noktası, AHTR’lerin saptanmasıdır. Çalışma döneminde araştırmanın kriterlerine uygun 94 transfüzyon yapıldı ve tümü çalışmaya dahil edildi. Bu transfüzyonların 73’ünde yeterli laboratuar incelemesi vardı ve AHTR gelişmediği gösterildi. Bu 73 transfüzyonda ortanca hemoglobin konsantrasyonu artışı 1,1 g/dL oldu. Üç transfüzyon erken sonlandırıldı, fakat ileri incelemelerde AHTR dışlandı. Diğer 21 transfüzyonda yeterli laboratuar incelemesi yapılamasa da bu transfüzyonların sorunsuz tamamlandığı ve klinik takiplerde transfüzyon reaksiyonu düşündürecek klinik bulgu gelişmediği belgelendi. Çalışmanın verileri, enzimli ortamda çapraz karşılaştırmanın transfüzyon öncesi taramada gerekli olmayabileceğinin klinik doğrulaması niteliğindedir ve bu kan ürünlerinin kısa dönemde etkin olduğunu göstermektedir. Özellikle transfüzyona bağımlı hastaların tedavisindeki önemi nedeniyle, izole enzimli ortam uyumsuzluğu olan ES transfüzyonlarının uzun dönem etkinliğinin ileriye dönük kontrollü çalışmalarla araştırılmasını teşvik edici sonuçlar elde edilmiştir.

OBJECTIVE: Haemolytic disease of the newborn (HDN) is an immune haemolytic anaemia from maternal alloantibodies. Rh immunoglobulin (RhIg) prophylaxis can prevent alloimmunization to the D antigen. However, RhIg is not universally available in Uganda. ABO incompatibility also causes HDN. We determined the prevalence of HDN among newborn infants with jaundice in Uganda.
METHODS: We conducted a prospective cross-sectional study at Kawempe National Referral Hospital, Kampala, Uganda. Infants aged 0-14 days with neonatal jaundice (or total bilirubin >50 μmol/L) were enrolled. Clinical evaluation and laboratory testing, including ABO, RhD typing and maternal antibody screen, were performed.
RESULTS: A total of 466 babies were enrolled. The mean (SD) age was 3.4 (1.5) days. Of newborn babies with jaundice, 17.2% (80/466) had HDN. Babies with HDN had lower haemoglobin (SD); 15.7 (2.7) compared with those without HDN; 16.4 (2.4) g/dL, p = 0.016; and a higher bilirubin (interquartile range); 241 (200-318) compared with those without HDN; 219 (191-263) μmol/L, p < 0.001. One baby had anti-D HDN, while 46/466 had HDN from an ABO incompatibility (anti-A 43.5% and anti-B 56.5%); 82% of babies with HDN also had suspected neonatal sepsis or birth asphyxia. About 79.2% (57/72) of mothers did not have ABO/Rh blood group performed antenatally. All infants with HDN survived except one.
CONCLUSIONS: Among newborn infants with jaundice, HDN is not rare. The majority is due to ABO HDN affecting group A and group B babies equally. Ensuring routine ABO/Rh grouping for all pregnant women is an area for improvement.

BACKGROUND: ABO incompatibility is not a contraindication but would affect the prognosis of allogeneic hematopoietic stem cell transplantation (allo-HSCT). The dynamic change of blood phenotype is not only related to the patient\'s status, but also the basis for the implementation of compatible blood transfusion. The criteria for judging a complete transformation to donor-type and the principle of blood transfusion at relapse need to be unified. We aimed to illustrate the significance of blood group monitoring after allo-HSCT.
METHODS: We collected 263 patients underwent ABO incompatible allo-HSCT from January 2010 to December 2019, and monitored blood type regularly according to the frequency of the patient\'s return visits till complete conversion or death. Non-parametric test was used to find differences among incompatible groups. We analyzed factors potentially influence blood type conversion by Binary Logistic model. Cox regression model was used to illustrate the relationship between blood-type conversion and prognosis.
RESULTS: The median days of conversion were 107, 91 and 108 in major-, minor- and bidirectional groups respectively. Blood type conversion correlated with HLA compatibility (P = 0.012, OR=2.69) and acute graft-versus-host-disease (P = 0.001, OR=0.06). Patients with incomplete blood type conversion had a higher death rate than those with complete blood type conversion(P = 0.003, OR=3.703).
CONCLUSIONS: Blood type monitoring can help to evaluate the prognosis of transplantation and assess the risk of death. It is recommended to monitor the changes of blood group antigens and antibodies, especially within a year after transplantation, to predict the risk of adverse events (such as GVHD, recurrence, death, etc.).