Does transfusion of Asian-type DEL red blood cells to D- recipients cause D alloimmunization?

Molecular basis of DEL phenotype in the Indian population: Insights from next-generation sequencing analysis of two cases

The DEL phenotype represents an intriguing and challenging aspect of blood group serology. This condition is characterized by an extremely weak expression of the D antigen on red blood cells, to the extent that it often eludes detection through routine serological methods. Identifying the DEL phenotype necessitates more specialized techniques, such as adsorption and elution tests, to reveal the presence of the D antigen. This distinctive phenotype underscores the complexity and subtlety of blood group genetics and highlights the importance of using advanced methods to accurately classify individuals with this condition, as their ability to form anti-D antibodies can have clinical implications during transfusion and pregnancy scenarios. There is a paucity of data for the DEL phenotype in the Indian population, and the molecular basis has not been elucidated yet. Our investigation delves into the genetic underpinnings of two distinct DEL phenotype cases that pose challenges for resolution through conventional serological techniques. We employ next-generation amplicon sequencing to unravel the intricate genetic landscape underlying these cases. In the D-negative donor, the DEL phenotype was first identified serologically, which was subsequently confirmed by molecular analysis. In the second case, it was associated with an anti-D antibody in a D-positive patient. Initial data analysis unveiled a substantial reduction in coverage across the exonic segments of the RHD gene in both samples, suggesting the potential presence of RHD exon deletions. On both occasions, we identified a homozygous intronic RHD polymorphism that is well established to be linked to the RHD* 01EL.32/RHD*DEL32 variant.

Patients with Asian-type DEL can safely be transfused with RhD-positive blood

Red blood cells (RBCs) of Asian-type DEL phenotype express few RhD proteins and are typed as serologic RhD-negative (D-) phenotype in routine testing. RhD-positive (D+) RBC transfusion for patients with Asian-type DEL has been proposed but has not been generally adopted because of a lack of direct evidence regarding its safety and the underlying mechanism. We performed a single-arm multicenter clinical trial to document the outcome of D+ RBC transfusion in patients with Asian-type DEL; none of the recipients (0/42; 95% confidence interval, 0-8.40) developed alloanti-D after a median follow-up of 226 days. We conducted a large retrospective study to detect alloanti-D immunization in 4045 serologic D- pregnant women throughout China; alloanti-D was found only in individuals with true D- (2.63%, 79/3009), but not in those with Asian-type DEL (0/1032). We further retrospectively examined 127 serologic D- pregnant women who had developed alloanti-D and found none with Asian-type DEL (0/127). Finally, we analyzed RHD transcripts from Asian-type DEL erythroblasts and examined antigen epitopes expressed by various RHD transcripts in vitro, finding a low abundance of full-length RHD transcripts (0.18% of the total) expressing RhD antigens carrying the entire repertoire of epitopes, which could explain the immune tolerance against D+ RBCs. Our results provide multiple lines of evidence that individuals with Asian-type DEL cannot produce alloanti-D when exposed to D+ RBCs after transfusion or pregnancy. Therefore, we recommend considering D+ RBC transfusion and discontinuing anti-D prophylaxis in patients with Asian-type DEL, including pregnant women. This clinical trial is registered at www.clinicaltrials.gov as #NCT03727230.

RhD alloimmunization by DEL variant missed in donor testing

INTRODUCTION

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.

MATERIAL AND METHODS

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.

RESULTS

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.

CONCLUSION

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.

Medical gloves modified by a one-minute spraying process with blood-repellent, antibacterial and wound-healing abilities

During clinical surgery, bleeding that occurs in the operative region is inevitable. Due to the blood adhesion on ordinary medical gloves, it reduces surgery quality to a certain extent and even prolongs operation time. Herein, we show that medical blood-repellent gloves (MBRG) can be obtained by spraying the blood-repellent mist spray (MS) on the surface of ordinary medical gloves, which are available for immediate use in around one minute. After the modification, MBRG not only have a significantly higher blood repellent rate than that of ordinary medical gloves, but also can effectively inhibit the growth of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), and even promote the healing of infected wounds. MS is easy to prepare, low-toxic, and can be widely used on the surface of various medical gloves, such as rubber gloves, polyethylene film gloves, and nitrile gloves, which may have an impact on the development of future medical gloves.

Molecular and computational analysis of 45 samples with a serologic weak D phenotype detected among 132,479 blood donors in northeast China

Background

RH1 is one of the most clinically important blood group antigens in the field of transfusion and in the prevention of fetal incompatibility. The molecular analysis and characterization of serologic weak D phenotypes is essential to ensuring transfusion safety.

Methods

Blood samples from a northeastern Chinese population were randomly screened for a serologic weak D phenotype. The nucleotide sequences of all 10 exons, adjacent flanking intronic regions, and partial 5′ and 3′ untranslated regions (UTRs) were detected for RHD genes. Predicted deleterious structural changes in missense mutations of serologicl weak D phenotypes were analyzed using SIFT, PROVEAN and PolyPhen2 software. The protein structure of serologic weak D phenotypes was predicted using Swiss-PdbViewer 4.0.1.

Results

A serologic weak D phenotype was found in 45 individuals (0.03%) among 132,479 blood donors. Seventeen distinct RHD mutation alleles were detected, with 11 weak D, four partial D and two DEL alleles. Further analyses resulted in the identification of two novel alleles (RHD weak D 1102A and 399C). The prediction of a three-dimensional structure showed that the protein conformation was disrupted in 16 serologic weak D phenotypes.

Conclusions

Two novel and 15 rare RHD alleles were identified. Weak D type 15, DVI Type 3, and RHD1227A were the most prevalent D variant alleles in a northeastern Chinese population. Although the frequencies of the D variant alleles presented herein were low, their phenotypic and genotypic descriptions add to the repertoire of reported RHD alleles. Bioinformatics analysis on RhD protein can give us more interpretation of missense variants of RHD gene.