African American Blood Donors Research Articles

Impact of predictive scoring model and e-mail messages on African American blood donors.

Expanding the African American (AA) donor pool is critical to sustain transfusion support for sickle cell disease patients. The aims were to: 1) apply cognitive computing on donation related metrics to develop a predictive model that effectively identifies repeat AA donors, 2) determine whether a single e-mail communication could improve AA donor retention and compare retention results on higher versus lower predictive score donors, and 3) evaluate the effect of e-mail marketing on AA donor retention with culturally versus nonculturally tailored message. Between 2011 and 2012, 30,786 AA donors donated blood at least once on whom predictive repeat donor scores (PRDSs) was generated from donor-related metrics (frequency of donations, duration between donations, age, blood type, and sex). In 2013, 28% (8657/30,786) of 2011 to 2012 donors returned to donate on whom PRDS was validated. Returning blood donors had a higher mean PRDS compared to nonreturning donors (0.649 vs. 0.268; p < 0.001). In the e-mail pilot, high PRDS (≥0.6) compared to low PRDS (<0.6) was associated with 89% higher donor presentation rate (p < 0.001), 20% higher e-mail opening rate (p < 0.001), and, specifically among those who opened the e-mail, 159% higher presentation rate (p < 0.001). Finally, blood donation rate did not differ (p = 0.79) as a function of generic (n = 9312, 1.4%) versus culturally tailored (n = 9326, 1.3%) message. Computational algorithms utilizing readily available donor metrics can identify highly committed AA donors and in conjunction with targeted e-mail communication has the potential to increase the efficiency of donor marketing.

Impact of Predictive Scoring Model and Email Messaging on African American Blood Donors

Impact of Predictive Scoring Model and Email Messaging on African American Blood Donors

Prevalence of Anti-Human Factor VIII Binding IgG Antibodies in Sickle Cell Disease Patients before and after Hematopoietic Stem Cell Transplantation

▪We have reported a case of acquired hemophilia A in our series of sickle cell disease patients treated with hematopoietic stem cell transplantation (HSCT) using HLA matched sibling donors, non-myeloablative conditioning, and sirolimus immunosuppression for GVHD prevention (Lozier et al, Haemophilia 2013). Subsequently we encountered another case in the 48 patients now transplanted. The objective of our transplant regimen is to establish a stable engraftment that will correct the sickle cell disease, with minimal morbidity. As a result of the non-myeloablative conditioning, our HSCT recipients typically display mixed chimerism between donor and recipient after HSCT with a post-HSCT immune system derived from both donor and recipient. We investigated the prevalence of FVIII-binding antibodies by ELISA in HSCT recipients prior to and after HSCT, and sought to determine if prior exposure to blood products, differences in FVIII haplotypes, and/or ethnicity may predispose to FVIII inhibitors. We measured IgG antibodies that bind FVIII by ELISA in 30 of our 48 transplanted subjects and donors for whom plasma, serum, and DNA were available, before and after HSCT. Published evidence suggests 3-19% of normal blood donors have detectable FVIII binding antibodies when tested in an ELISA format (Krudysz-Amblo et al, Blood 2009; Whelan et al, Blood 2012). We were surprised to find that 22 of 30 recipients (73%) had measurable titers of ≥ 1:50 prior to HSCT. We also assessed their sibling donors as a control group and found 13 of 24 evaluable donors had titers ≥ 1:50 (54%). Measurement of antibodies to FVIII in African-American blood donors at NIH showed 8 of 13 (62%) to have ≥ 1:50 titers, in contrast to only 1 of 20 Caucasian (5%) NIH blood donors tested (P < 0.05). This suggests African-Americans are more likely to form antibodies to FVIII than Caucasians, and might explain the two cases of acquired hemophilia A in our HSCT study. This has not been reported in allogeneic HSCT studies, though 2 out of 155 autologous HSCT patients with autoimmune diseases were reported to have acquired hemophilia after HSCT (Loh et al, Blood 2007). Of 8 patients with titers <1:50, 6 had no increase in titers measured out to two years after HSCT; 2 had peak post-transplant titers of 1:50 or 1:100 at most, and none developed FVIII inhibitors. Of 22 patients with titers of ≥ 1:50 pre-transplant two developed FVIII inhibitors and 20 had unchanged or diminishing titers following HSCT (P = 0.38, for inhibitor development, NS). We investigated the possibility that transfusions with red blood cells for sickle cell disease might have sensitized patients, either by exposure to "foreign" FVIII protein or by modulation of the immune system, prior to HSCT. Of the 8 patients with titers < 1:50 pre-transplant, one recalled transfusion with > 50 units of RBCs prior to transplant (12.5%), while 9 of 22 with titers ≥ 1:50 prior to transplant (41%) recalled transfusion with > 50 units of RBCs prior to transplant (P = 0.14, NS). Six haplotypes of the FVIII protein are known, and empiric data suggests uncommon haplotypes more prevalent in African-Americans may be associated with higher rates of FVIII inhibitors in African-Americans with hemophilia A after FVIII treatment (Viel et al, NEJM 2009), and rare FVIII polymorphisms are associated with acquired hemophilia A in the Caucasian population as well (Tiede et al, Ann Hematol 2010). We ascertained FVIII haplotypes in HSCT recipients and their donors to see if mismatches between donor and recipient may be associated with FVIII antibodies or inhibitors. Of 30 patients studied, there were 27 for whom DNA data permitted us to infer haplotypes. Fourteen recipients were identical matches to their donors, of whom one (7%) had an increase in titer from baseline after transplant; none developed an inhibitor. Of 15 recipients with mismatches in FVIII haplotypes with their donors, 3 had increases from baseline titers after transplant (20%), including the two FVIII inhibitor patients (P = 0.45, NS). Our study shows that African-Americans have a higher prevalence of low-titer/subclinical anti-human FVIII antibodies compared to Caucasians which may explain subsequent FVIII inhibitors in the setting of hematopoietic stem cell HSCT. Neither greater recalled exposure to RBC transfusions pre-HSCT nor mismatch of FVIII haplotypes with donor explain the risk of inhibitor development. DisclosuresNo relevant conflicts of interest to declare.

Designated Donor Program Enrollment Does Not Affect Red Blood Cell Alloimmunization Rates in Children with Sickle Cell Disease on Chronic Transfusion Therapy

Background:Chronic red blood cell (RBC) transfusion therapy is the predominant treatment modality in children with sickle cell disease (SCD) at high risk of first or recurrent strokes. RBC alloimmunization develops in some patients receiving chronic transfusion therapy, due in part to genetic differences in the prevalence of blood group antigens between the patient population and the blood donor pool. Many children’s hospitals have developed designated donor or “buddy” programs to recruit African-American blood donors and assign them to specific SCD patients with matched phenotypes, particularly in the Rh and Kell antigen groups, to reduce the likelihood of RBC alloimmunization. However, the practical constraints of such programs may make it difficult to ensure that patients’ transfusions always come from designated donors. Moreover, it is unclear whether such programs result in a lower risk of RBC alloimmunization when compared to the use of non-designated-donor but phenotype-matched RBC units. We aimed to determine the proportion of transfusions from designated donors at our institution, hypothesizing that the development of new RBC alloantibodies is associated with a lower proportion of transfused units from designated donors.Methods:This is a single-institution retrospective cohort study of 38 patients with SCD who received chronic transfusion therapy (manual exchange or erythrocytapheresis) for primary or secondary stroke prevention from 1/1/2008 through 12/31/2012. Patients on transfusion therapy for 6 or more months were included. Subjects were censored at last date of follow-up or date of hematopoietic stem cell transplant. The local designated donor program was started in 1999. Designated donors are selected to be ABO/RhD compatible and phenotype-matched to patients for the C, E, and K antigens. When units from designated donors are not available, compatible units phenotype-matched for C, E, and K are issued from general inventory. The number and percentage of units transfused from either designated or non-designated donors, and the identification of new RBC alloantibodies during the study period, were evaluated. The rates of alloimmunization were compared between patients who received a “high” (above the median) or “low” (below the median) proportion of designated donor units. Categorical variables were compared with Fisher’s exact test and medians with the Mann-Whitney U-test in SPSS version 21 (IBM, Armonk, NY). A p-value below 0.05 was statistically significant.Results:During the study period, 38 subjects (42% male) met all inclusion criteria. A median of 120 units (IQR 60-186) was transfused to each subject, and each subject received a median of 63% (IQR 45%-77%) of units from designated donors. Of the 38 subjects, 18 (47%) produced at least one newly identified RBC alloantibody during the study period. Among these 18 antibody producers, a total of 29 new alloantibodies were detected, with a range of 1-3 per subject. Ten of the newly identified alloantibodies were directed against C, D, E, or K. No statistically significant difference between antibody producers and non-producers was identified for total number of RBC units transfused (median 161 vs. 96, p = 0.067), number of units transfused from designated donors (median 107 vs. 49, p = 0.099), number of non-designated-donor, phenotype-matched units transfused from general inventory (median 38 vs. 26, p = 0.059), or proportion of units transfused from designated donors (median 68% vs. 49%, p = 0.28). Although there was a trend toward a higher incidence of alloimmunization in patients who received a high proportion of designated donor units (OR 2.4, CI 0.6-8.7), it was not statistically significant (p= 0.33).Conclusions:Despite receiving phenotypically matched RBC units, almost half of the children with SCD on chronic transfusion therapy in this cohort developed new RBC alloantibodies during a five-year period. The number of units transfused from a designated donor did not significantly affect alloimmunization rate. One-third of the new alloantibodies were directed against antigens specifically matched for in the designated donor program. Patient-specific factors, such as genetic variation in the Rh locus, may be responsible for the risk of alloimmunization. Alternative matching strategies, such as genotypic matching of RBC donors and recipients, should be explored in prospective studies. DisclosuresJackups:Immucor: Consultancy.

Comments on: Molecular matching of red blood cells is superior to serological matching in sickle cell disease patients

Comments on: Molecular matching of red blood cells is superior to serological matching in sickle cell disease patients

DARCalleles and Duffy phenotypes in African Americans

The DARC (Duffy blood group, chemokine receptor) gene encodes for a transmembrane glycoprotein that functions as a chemokine transporter, is a receptor for Plasmodium vivax and P. knowlesi, and expresses the Duffy blood group antigens (Fy). The Fy(a-b-) phenotype found in people of African descent is typically associated with a -67t>c mutation in the 5'-untranslated region (UTR), which prevents red blood cells being invaded by P. vivax and P. knowlesi. The aim of this study was to establish DARC allele frequencies in an African American blood donor cohort, determine a phylogenetic tree for DARC, and compare human and Neandertal DARC genes. The DARC nucleotide sequence of 54 African American blood donors was determined from genomic DNA. Heterozygous substitutions were resolved by sequencing of haplotype-specific amplifications. A phylogenetic tree for DARC was established using the neighbor-joining method with Pan troglodytes as root. A total of 108 haplotypes of the DARC gene could be unambiguously determined from nucleotide position -300 in the 5' UTR to +300 in the 3' UTR. Eleven different alleles were found, including the clinically relevant FY*A, FY*B, FY*B-67C, FY*B298A, and FY*X alleles. All phenotype predictions based on genotypes matched the serologically determined phenotypes exactly: 52% Fy(a-b-), 28% Fy(a-b+), and 20% Fy(a+b-). The nucleotide sequencing approach using one amplicon is a practical genotyping method for DARC and allows the determination of haplotypes even in heterozygous constellations. We developed a phylogenetic tree for DARC alleles and postulated a distinct FY*B allele as ancestral for the extant DARC alleles in humans.

The Sickle Cell Sabbath: a community program increases first‐time blood donors in the African American faith community

Blood transfusion therapy is an established treatment for primary and secondary prevention of strokes in children with sickle cell disease (SCD), a disease that predominantly affects African Americans. African American blood donors are more likely to have compatible minor red blood cell antigens for children with SCD who routinely receive transfusions. This study tested the hypothesis that when informed at church about the importance of blood donation, African Americans will have a higher than expected rate of first-time blood donation compared to the general population. The Sickle Cell Sabbath Program was developed to increase awareness about SCD and the importance of blood donations within the African American faith community. Church involvement in the program included a 5-minute scripted educational session about SCD that included the importance of blood donations followed by a blood donor drive that was hosted by the church. Thirteen African American churches sponsored 34 blood drives from 2003 through 2006. Each church sponsored at least two blood drives. Approximately 1200 donors participated in the sickle cell blood drives. The majority of the donors were first-time donors and represented a greater than expected first-time donor rate when compared to first-time donors in the metropolitan St Louis area, 60 percent (422 of 699) and 12.2 percent (21,516 of 175,818), respectively (p = 0.001). An educational program that engages the African American faith community more than quadruples the rate of expected first-time blood donors when compared to the general community over this 4-year period.

Transfusion practices for patients with sickle cell disease at a major academic medical center

Abstract The University of North Carolina at Chapel Hill (UNC) is a tertiary-care, academic university hospital and a major referral center for patients across the state of North Carolina. This 700-bed, Level 1 trauma center transfuses more than 22,000 RBC units to patients annually. Clinical services and areas of the hospital which rely most heavily on transfusion support for their activities are transplantation (bone marrow and solid organ), hematology, critical care (medical and surgical intensive care units), cardiothoracic surgery, pediatrics, the operating room, the emergency department, labor and delivery, dialysis, and outpatient services. UNC is recognized for its expertise in coagulation, transfusion medicine, and hematology, particularly in sickle cell disease (SCD). The sickle cell center at UNC, which began in 1980 and continues today, in conjunction with our neighboring institution, Duke University Medical Center, is designated as part of a National Institutes of Health comprehensive sickle cell center. Several of the physicians are dedicated to the care of pediatric and adult patients with SCD, as well as to research on transfusion management of these patients and recruitment of African American blood donors. This article describes the practices of this institution for transfusion management of patients with SCD, as well as some of its efforts related to this challenging area of transfusion medicine. Immunohematology 2006;22:103–107.

Screening with monoclonal anti-Fy3 to provide blood for phenotype-matched transfusions for patients with sickle cell disease.

In the United States, there is a shortage of blood group phenotype-matched red cells (RBCs) for patients with sickle cell disease (SCD). A protocol designed to supply phenotype-matched RBCs for these patients by combining the recruitment of African American blood donors and automated testing of RBCs for these patients for the presumptive Fy(a-b-) phenotype using monoclonal anti-Fy3 was evaluated. African American donors were recruited, to increase the likelihood of phenotype matches in the donor population. Samples of RBCs were tested for the presumptive Fy(a-b-) phenotype by using monoclonal anti-Fy3 and an automated blood typing analyzer. RBCs confirmed to be Fy(a-b-) were retyped for selected Rh, MNS, Kell, Duffy, and Kidd blood system antigens. The extended phenotypes were matched with those of 41 SCD patients requiring transfusions. Of 8323 blood donations during the study, approximately 40 percent (3329) were made by African Americans. Approximately 22 percent (737) of African Americans were identified as Fy(a-b-) by this protocol and 12 percent (410) were phenotype matches for the 41 SCD patients. Combining the recruitment of African American blood donors and automated phenotyping using monoclonal anti-Fy3 offers a practical, relatively low-cost strategy for supplying phenotype-matched RBCs for SCD patients. This protocol increases the options for addressing the shortage of phenotype-matched RBCs for SCD patients.

The incidence of V (Rh10) and Jsa (K6) in the contemporary African American blood donor

Abstract Following an apparent increase in the number of patients with anti- V and/or anti-Jsa who required V– and/or Js(a–) red cell units, red cells from African American blood donors negative for C, E, S, K, Fya, Fyb, and Jkb were typed for V and Jsa over a 2-year period. Of the 438 donors typed for V and Jsa, 168 (38.36%) were V+ and 71 (16.44%) were Js(a+). The incidence of V (Rh10) was higher than that reported in previous studies, but no change was seen in the incidence of Jsa (K6). Immunohematology 1994;10:136–138.