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.

OBJECTIVE: Solid organ transplant surgeries including liver transplants constitute a substantial risk of bleeding complications and given frequent national blood shortages, supporting D-negative transplant recipients with D-negative red blood cell products perioperatively can be difficult for the transfusion services. This study was designed to compare the incidence of alloimmunization after D-mismatched red cell transfusions between patients with and without a history of solid organ transplant at a single tertiary care hospital. The patients undergoing solid organ transplants are on strong immunosuppressive regimens perioperatively to help reduce the risk of rejection. We hypothesized that the use of these immunosuppressive agents makes these patients very less likely to mount an immune response and form anti-D antibodies when exposed to the D-positive red blood cell products perioperatively.
METHODS: At our center, D-negative patients who received ≥1 unit of D-positive red blood cell products were identified using historical transfusion records. Antibody testing results were examined to determine the incidence of the formation of anti-D and any other red cell alloantibodies after transfusion and these results were compared between patients with and without a history of solid organ transplant.
RESULTS: We were able to identify a total of 22 patients over 10 years with D-negative phenotype who had undergone a solid organ transplant and had received D-positive red blood cell products during the transplant surgeries. We also identified a second group of 54 patients with D-negative phenotype who had received D-positive red blood cell products for other indications including medical and surgical. A comparison of the data showed no new anti-D formation among patients with a history of D mismatched transfusion during solid organ transplant surgeries.
CONCLUSIONS: Among our limited study population, we observed a very low likelihood of D alloimmunization among solid organ transplant recipients. A larger, prospective study could help further evaluate the need for prophylactic D matching for red cell transfusions during solid organ transplant surgeries.

BACKGROUND: Prehospital low-titer group O whole blood (LTOWB) used for patients with life-threatening hemorrhage is often RhD positive. The most important complication following RhD alloimmunization is hemolytic disease of the fetus and newborn (HDFN). Preceding clinical use of RhD positive LTOWB, we estimated the risk of HDFN due to LTOWB prehospital transfusion in the Finnish population.
METHODS: We collected data on prehospital transfusions in Tampere and Helsinki University Hospital areas. Using the mean of reported alloimmunization rates in trauma studies (24%) and a higher reported rate representing trauma patients of 13-50 years old (42.7%), we estimated the risk of HDFN and extrapolated it to the whole of Finland.
RESULTS: We estimated that in Finland, with the current prehospital transfusion rate we would see 1-3 cases of severe HDFN due to prehospital LTOWB transfusions every 10 years, and fetal death due to HDFN caused by LTOWB transfusion less than once in 100 years.
CONCLUSIONS: The estimated risk of serious HDFN due to prehospital LTOWB transfusion in the Finnish population is similar to previous estimates. As Finland routinely screens expectant mothers for red blood cell antibodies and as the contemporary treatment of HDFN is very effective, we support the prehospital use of RhD positive LTOWB in all patient groups.

UNASSIGNED: Isoimmunization is a process of immunizing an antigen-negative pregnant individual with a paternally derived fetal antigen. Although the Rh systems contain many antigen subtypes (D, C, c, E, e), the RhD antigen is highly immunogenic. This research aimed to investigate the perinatal Outcome of pregnant women with RhD sensitization at St. Paul\'s Hospital Millennium Medical College (SPHMMC), Ethiopia.
UNASSIGNED: A facility-based retrospective cross-sectional study was conducted on 98 pregnant women with RhD alloimmunization at SPHMMC from September 11, 2016, to September 10, 2021. SPSS 26 was used for data analysis. Descriptive statistics were utilized to assess the perinatal outcome of pregnant women with RhD alloimmunization. Fisher\'s exact test was used to determine which association, and a P value <0.05 was considered statistically significant.
UNASSIGNED: From the 98 pregnancies (06 - hydropic, 92 - non-hydropic) at high risk for fetal anemia, 45.9% of cases had MCA-PSV above 1.5MoM. Among these, 21.42% of all fetuses received an intrauterine transfusion. Forty-three IUTs were performed in 21 fetuses. The median number of transfusions per fetus was two. About 52.4% of the transfused fetuses had severe anemia, and 28.6% had moderate anemia. Prediction of MCA PSV ≥1.5MOM in diagnosing moderate-severe anemia in pregnant women with RhD sensitization 81%. General neonatal survival of alloimmunizations was 93.8%, 90.5% with IUT, 50% with hydrops fetalis, and 96.7% without hydrops.
UNASSIGNED: This research provides evidence that MCA PSV ≥1.5MoM is modest predictor of moderate-severe anemia in untransfused fetuses. This study was a step toward the development of more extensive and multicenter studies on the Perinatal Outcome of pregnant women with RhD sensitization in Ethiopia. Extra studies are needed to evaluate strategies for estimates of fetal anemia after blood transfusion as a result of the absence of information on the IUT database.

Exposure to normal or variably expressed RhD antigens in an antigen-negative individual can elicit an immune response and lead to the formation of clinically significant anti-D alloantibodies. We present the case of anti-D alloimmunization by DEL variant missed in routine blood donor screening.
Blood donors were typed for D antigen using the direct serologic micromethod. Nonreactive samples were confirmed in the indirect antiglobulin method with an IgM/IgG anti-D monoclonal reagent. Genomic DNA was extracted using a commercial QIAamp DNA Blood Mini kit on the QIAcube device (Qiaqen, Germany). RHD genotyping was performed using the PCR-SSP genotyping kits- Ready Gene D weak, Ready Gene D weak screen, Ready Gene CDE, and Ready Gene D AddOn (Inno-Train, Germany). Unidentified alleles were sent for DNA genome sequencing.
After identifying DEL positive blood units in RhD negative blood donor pool, a look-back study was performed to determine if their previous donations caused alloimmunization in recipients. Out of 40 D negative recipients, one developed anti-D alloantibody after 45 days. The patient did not receive other RhD positive blood products. Blood donor typed D negative in direct and indirect agglutination method. RHD screening was positive, but RHD genotyping and DNA sequencing showed no mutation indicating the normal genotype.
Currently used methods in RHD genotyping are insufficient to identify many variant alleles, especially intronic variations. We suggest additional gene investigation including yet unexplored regions of regulation and intron regions to justify our serological finding.

UNASSIGNED: Despite the availability guidelines to prevent RhD alloimmunization, severe hemolytic disease of fetus and newborn still occurs in high-income countries. The aim of the study was (1) To assess variations in practices for the prevention of RhD alloimmunization, and (2) to understand midwives\' acceptance and appropriation of fetal RhD genotyping.
UNASSIGNED: Descriptive cross-sectional survey of French midwives from September 2017 through January 2018. Participants were asked to complete an internet-based questionnaire that included three clinical vignettes. They were questioned about their practices concerning early pregnancy visit by RhD-negative women, prevention of RhD alloimmunization in women with second-trimester metrorrhagia, and RhD fetal genotyping.
UNASSIGNED: A total of 827 midwives completed the questionnaire. Only 21.1% reported that they practice all the preventive measures recommended in early pregnancy. In a situation at high risk of RhD alloimmunization during pregnancy, 97.2% of midwives would perform immunoprophylaxis. Nearly, all midwives reported providing information about RhD alloimmunization (92.4%) at the beginning of pregnancy, although only 11.3% offered both written and verbal information; at the time of systematic anti-D immunoprophylaxis (28 weeks), 78% provided information, but only 2.7% both verbally and in writing. Finally, only 50.8% of midwives preferred to include RhD fetal genotyping in routine prenatal prophylaxis.
UNASSIGNED: This study showed significant variations in French midwives\' practices to prevent RhD alloimmunization. Better dissemination of guidelines is needed to improve both consistent use of these practices and the quality of information delivered to RhD-negative pregnant women.

METHODS: Review article.
METHODS: Department of Obstetrics and Gynecology, Palacky University Olomouc, Faculty of Medicine and Dentistry, University Hospital Olomouc. Methods, results: Every person exposed to a foreign red blood cell antigen (erythrocyte antigen) develops an antibody. If the contact with a foreign erythrocyte antigen occurs during pregnancy, the erythrocyte alloimmunization of the pregnant woman develops and, due to antibodies crossing through the placenta also Haemolytic disease of the foetus and newborn (HDFN) can occur. Antibodies are made by pregnant woman's immune system and their quantity and quality depend on many factors. Their function is to eliminate foetal \"foreign\" erythrocytes. Ways of elimination of antibody-labelled foetal erythrocytes are the same in the bloodstream of pregnant women and foetuses/newborns and their principle is type II hypersensitivity (cytotoxic), according to the Coombs and Gell classification. Severe forms of HDFN can lead to increased perinatal morbidity and mortality. Prevention of the development of RhD alloimmunization and severe forms of HDFN is based on the administration of polyclonal immunoglobulin (Ig) G anti-D in all potentially sensitizing events. It is assumed that the mechanism of anti-D IgG action is based on the rapid removal of the antigen by antibody overflow, and on antibody mediated immune suppression (AMIS). However, the exact immunological principle is not fully known yet.
CONCLUSIONS: This article describes the development of irregular antibodies, methods of foetal erythrocytes destruction and the mechanism of prevention of anti-D immunoglobulin from the immunological point of view.