Tauscher, Craig D.

Abstract Background Babesia and Plasmodium are intraerythrocytic parasites that cause babesiosis and malaria, respectively. Significant associations between human blood group antigens and malaria are known; however, few studies have examined the relationship between blood group antigens and babesiosis. Study Design and Methods From June to August 2025, 100 Babesia polymerase chain reaction (PCR)− and 100 B. microti PCR+ human patient samples tested at a national reference laboratory underwent ABO and D phenotyping and red blood cell (RBC) genotyping of 37 antigens. Results The predicted phenotype of S‐s+ was found in 32% and 50% of Babesia − and B. microti + patients, respectively (χ 2 = 5.97, p = .015, odds ratio = 2.125, 95% confidence interval 1.18–3.78). Two B. microti + patients had the predicted phenotype of Fy(a‐b‐), meaning that Duffy is unlikely to be an essential invasion receptor. There were no statistically significant differences in ABO or D expression between the groups. Discussion Because multiple testing corrections were not applied to the statistical analyses, the S/s predicted phenotype results must be viewed as hypothesis‐generating. This may be the first study to link B. microti infection to human RBC S/s antigens, which are known to impact B. divergens and P. falciparum . Additional studies are needed to understand the impact of the babesiosis patient's blood type on B. microti infection and whether the transfusion of RBCs expressing specific antigens can impact the disease.

AbstractBackgroundTandem mass spectrometry (MS/MS) has become a common clinical laboratory testing modality has demonstrated success in distinguishing between small protein variations in transthyretin amyloidosis. Since many common clinically significant RBC antigens are also small protein variations, this study aimed to determine if MS/MS could correctly detect common RBC antigens within the Rh, Kell, Duffy, MNS, Kidd, Diego, and Lutheran blood group systems.Study Design and MethodsResidual samples from serotyped/genotyped blood donors at a hospital‐based blood donation center from February to August 2021 were analyzed. RBC membrane protein preparations underwent protease digestion prior to MS/MS analysis for RhD, RhCE, Kell, atypical chemokine receptor 1 (Duffy), glycophorin A (MNS), glycophorin B (MNS), urea transporter 1 (Kidd), band 3 anion transport protein (Diego), and basal cell adhesion molecule (Lutheran). Untargeted liquid chromatography (LC)‐MS/MS detected protein‐specific peptides, while targeted LC‐selected reaction monitoring (LC‐SRM) detected RBC antigen‐containing peptides.ResultsThrough the use of multiple proteases, untargeted LC–MS/MS detected protein‐specific peptides in all but glycophorin B, with band 3 anion transport protein, basal cell adhesion molecule, Kell, and glycophorin A having the greatest protein sequence coverage. Targeted LC‐SRM detected antigen‐specific peptides for Cw, Dia/Dib, Kpb, and Wra/Wrb, which agreed with the donors' previous typing results.DiscussionMS/MS can successfully detect peptides from several blood group systems but only detected a subset of their common RBC antigens. Further sample enrichment and MS/MS detection improvements will need to occur before MS/MS could be considered a clinical RBC phenotyping modality.

AbstractBackgroundDaratumumab (Dara), an anti‐CD38 monoclonal antibody for hematologic malignancies, interferes with routine blood bank testing, specifically affecting the antibody screen and identification panels. In 2016, the AABB recommended performing a baseline phenotype or genotype before a patient (Pt) begins taking anti‐CD38 to avoid this interference and potential problems with transfusion. The objective of this study was to assess red blood cell (RBC) utilization and subsequent incidence of alloimmunization to the transfused RBCs in patients receiving Dara.Methods and MaterialsWe monitored 244 patients taking Dara to determine their red blood cell transfusions and incidence of clinically significant antibody formation before and following administration of Dara. Poisson generalized estimating equations with log link were used comparing the post‐Dara incidence and prevalence to those prior, with significance defined as p < .05.ResultsFrom September 1, 2015 to December 22, 2018, 244 patients on Dara were identified, of which 145 patients (59.4%) received a red blood cell transfusion. Antibody screens were performed on 97 of the 145 patients at least 2 weeks following RBC transfusion. Four of the total transfused patients (2.8% total, 4.1% patients with follow‐up antibody screen testing) formed new clinically significant alloantibodies, which was not significantly different from Asare's hematologic incidence (p = .98/p = .49).ConclusionsThis study showed our patients on Dara did not form alloantibodies following RBC transfusion at a higher incidence than similar patient populations.

Abstract Patients requiring chronic transfusion support are at risk of alloimmunization after red blood cell (RBC) transfusion because of a disparity between donor and recipient antigen profiles. This research explored the probability of obtaining an exact extended phenotype match between blood donors randomly selected from our institution and patients randomly selected from particular ethnic groups. Blood samples from 1,000 blood donors tested by molecular method were evaluated for the predicted phenotype distribution of Rh, Kell, Kidd, Duffy, and MNS. A random subsample of 800 donor phenotypes was then evaluated for the probability of obtaining an exact match with respect to phenotype with a randomly selected patient from a particular ethnic group. Overall, there was a greater than 80 percent probability of finding an exact donor-recipient match for the K/k alleles in the Kell system. The probability ranged from 3 percent to 38 percent, depending on the ethnicity and disparities in phenotypic profiles, for the Rh, Kidd, Duffy, and MNS systems. A significant donor-recipient phenotype mismatch ratio exists with certain blood group antigens such that, with current routine ABO and D matching practices, recipients of certain ethnic groups are predisposed to alloimmunization. Immunohematology 2011; 27:12–19.

AbstractBackgroundPrimary cold agglutinin disease (CAD) is a monoclonal antibody (M‐protein) and complement‐mediated chronic hemolytic disease process. Antibody glycosylation can play a role in both antibody half‐life and complement fixation. Recently, M‐protein light chain (LC) glycosylation has been shown to be associated with AL amyloidosis. We hypothesized that M‐protein LC glycosylation is also associated with cold agglutinin (CA) titers and CA‐mediated hemolysis.Study Design and MethodsA cross‐sectional study of patients undergoing CA titer evaluation underwent mass spectrometric analysis for M‐proteins and M‐protein LC glycosylation. A subset of serum samples also underwent evaluation for the ability to trigger cold hemolysis in vitro. M‐protein and M‐protein LC glycosylation rates were compared across CA titer groups, clinical diagnosis, direct antiglobulin testing (DAT) results, and cold in vitro hemolysis rates.ResultsBoth M‐protein and M‐protein LC glycosylation rates significantly differed across CA titer groups with the highest rates in those with elevated CA titers. M‐protein LC glycosylation occurred almost exclusively on IgM kappa M‐proteins and was significantly associated with positive DAT results and a clinical diagnosis of CAD. Cold in vitro hemolysis was demonstrated in two patients who both had a CA titer of more than 512 but there was no significant association with CA titer group or M‐protein LC glycosylation status.ConclusionM‐protein LC glycosylation is significantly associated with higher CA titer levels. Given the role that antibody glycosylation can play in antibody half‐life and complement fixation, further studies are needed to clarify the effects of LC glycosylation within the context of CAD.

AbstractBackgroundHemolytic disease of the fetus and newborn (HDFN) attributable to anti‐M is rare, although case reports implicate anti‐M in varying severities of HDFN, including fetal hydrops and intrauterine death.Case DescriptionWe describe the case of a newborn with HDFN associated with an atypical immunoglobulin (Ig) G anti‐M that reacted best at cold temperatures. The maternal antibody detected in pregnancy was not reactive at 37°C, and a direct antiglobulin test (DAT) on red blood cells (RBCs) from the newborn was negative, suggesting an anti‐M that should not have been clinically relevant. However, the infant developed hyperbilirubinemia (bilirubin level, 17.6 mg/dL), hemolytic anemia (hemoglobin nadir, 5.5 g/dL), and reticulocytopenia. Laboratory testing demonstrated the presence of an IgG anti‐M in maternal and neonatal samples reacting best at 4°C. This passively acquired IgG anti‐M provoked hemolytic anemia in the infant and likely suppressed erythropoiesis, resulting in reticulocytopenia with prolonged anemia. He was treated for IgG anti‐M HDFN with 10 intravenous Ig infusions and 10 days of oral prednisone followed by a taper. He required seven transfusions with M− RBCs. His hemoglobin level normalized at 3 months of age. Follow‐up at 2 years revealed no hematologic or neuro‐developmental concerns.ConclusionTo our knowledge, this is the second report of HDFN attributable to an IgG anti‐M reacting preferentially at cold temperature with no 37°C reactivity. Clinically relevant IgG anti‐M may elude standard testing. Early recognition and testing for cold‐reacting IgG anti‐M should be considered for newborns with hemolysis, a negative DAT, and prolonged anemia.

Purpose: molecular testing is often indicated for recently transfused patients. However, there are no guidelines regarding the potential interference from donor DNA or whether it is necessary to wait for a period of time post-transfusion prior to genetic testing. While the majority of patients are transfused in the non-trauma setting using leukoreduced (LR) red blood cell products, the degree of leukoreduction varies among centers and is not universally practiced. Methods: whole blood units collected from anonymous donors were used in an in vitro transfusion model. One unit was split: half being leukoreduced simulating a leukopenic recipient and half left untreated. Donors were simulated by leukoreduced, partially leukoreduced (PLR), or non-leukoreduced units, transfused in 2, 5, or 16 unit equivalents. DNA from the combinations were subjected to short tandem repeat (STR) analysis for chimerism detection. Results: donor DNA was not detectable in any of the LR combinations, but detected in the PLR combinations, ranging from 0.1 to 1.5% donor DNA in the immunocompetent recipient and 6.3–27.8% in the leukopenic recipient. Non-LR donor DNA was also detected (13–95%). Conclusion: donor-derived DNA from leukoreduced blood products is unlikely to interfere with the interpretation of germline genetic testing in immunocompetent recipients but may interfere in immunocompromised recipients.