Duffy Antigen Research Articles

Abstract PO-141: The role of African Duffy-null allele related inflammation on the tumor microenvironment

Abstract DARC/ACKR1 erythrocyte expression, also known as the “Duffy blood group,” is understood to sequester pro-inflammatory chemokines and thereby regulate circulating gradients that direct immune cell infiltration. We hypothesize that this function also determines immune cell landscapes in the tumor microenvironment. Due to evolutionary selection pressures of malaria, individuals with sub-Saharan African ancestry typically carry the Duffy-null allele (rs4849887) and this lack of DARC/ACKR1 expression gives immunity to malaria while also allowing chronically high inflammation levels. Over 68% of African Americans (AA) have been found to have the Duffy-null genotype, compared to a rare 1-3% in European American individuals and we have shown it increases predisposition for Triple-Negative Breast Cancer (TNBC). In addition, we are currently studying if Duffy-null may contribute to higher breast cancer mortality that disproportionately affects AA women. This may be in part due to the role that low-DARC/ACKR1 expression plays in chronic inflammation, altering levels of several chemokines that modulate the migration and differentiation of specific immune cells. This role will impact tumor immune cell infiltration as well as the immune cell population composition overall, depending upon levels of DARC/ACKR1. Using RNA sequencing, our initial results indicated that for breast cancer tumors with high DARC/ACKR1 expression there was a higher estimated presence of CD8+ T cells, CD4+ T cells, regulatory T cells, follicular helper T cells, and memory B cells. Whereas with low DARC/ACKR1 expression, there was markedly less expression of resting dendritic cells and memory B cells. Therefore, in order to ascertain the influence DARC status has on spatial deposition and functional status of immune cell landscapes across the tumor microenvironment, we performed imaging mass cytometry on primary TNBC tumors. The panel contained tumor, structural, and immune markers, and was used to characterize the spatial differences between samples that had been verified to be DARC-high or DARC-low through immunohistochemistry. Our imaging analyses indicated that high DARC/ACKR1 expression correlates with infiltration of monocytes, macrophages, and cytotoxic T cells into the solid tumor microenvironment. Conversely, tumors with low DARC/ACKR1 expression showed monocytes and cytotoxic T cells contained in the tumor stroma. Using single-cell phenotyping, we were also able to identify distinct cell populations between DARC-high and -low. The tSNE analysis and heatmaps performed using Histology Topography Cytometry Analysis Toolbox (histoCAT), allowed us to visualize the spatial distribution of these cell populations, indicating an immune-suppressive tumor microenvironment in DARC-low tumors. These differences may be implicated in the causality of tumor progression as well as how to approach treatment given the cell heterogeneity of TNBC. This work provides greater context on the role that Duffy-null plays in chronic inflammation on the tumor microenvironment. Citation Format: Yanira Guerra, Rachel Martini, Jessica Bensenhaver, Yalei Chen, Joseph K. Oppong, Ishmael Kyei, Frances S. Aitpillah, Michael O. Adinku, Joseph K. Oppong, Ernest K. Adjei, Aisha Jibril, Baffour Awuah, Mahteme Bekele, Engida Abebe, Kwasi Ankomah, Ernest B. Osei-Bonsu, Kofi K. Gyan, Clayton Yates, Kim Blenman, Olivier Elemento, Lisa Newman, Melissa B. Davis. The role of African Duffy-null allele related inflammation on the tumor microenvironment [abstract]. In: Proceedings of the AACR Virtual Conference: 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2021 Oct 6-8. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PO-141.

Serological and Molecular Study of the Duffy Blood Group among Malarial Endemic Region Residents in Brazil.

ABSTRACTBackground: The atypical chemokine receptor 1 (ACKR1) gene encodes the Duffy blood group antigens in two allelic forms: FY*A (FY*01) and FY*B (FY*02), which define the Fy(a+b-), Fy(a-b+), and Fy(a+b+) phenotypes. FY*BES (FY*02N.01) is a single T to C substitution at nucleotide -67 that prevents the FY*B from being expressed in red blood cells (RBCs). Methods: We evaluated 250 residents from a Brazilian malarial endemic region (RsMR). All individuals were phenotyped for Fya and Fyb antigens and genotyped for FY*A, FY*B, FY*B SE , and FY*B weak alleles. Results: Among the 250 individuals, 209 (83.6%) reported previous malaria infection, and 41 (16.4%) did not. The Fy(a+b+) phenotype was present in 97/250 (38.8%), while the Fy(a-b-) was present in 7/250 (2.8%). The FY*A/FY*B was found in 130/250 (52%) and the FY*A/FY*A in 45/250 (18%). The c.1-67>TC was present, in homozygosity, in 11/250 (4.4%). Among 34 individuals with the Fy(a+b-) and FYA*/FYB* mutations, 4/34 (11.8%) had homozygosity for the c.1-67T>C. One individual presented the Fy(a+b-), FY*A/FY*B, and c.1-67T>C in homozygosis, whereas the other presented the Fy(a+b-), FY*A/FY*A, and c.1-67T>C in heterozygosis. Conclusions: We reported a low prevalence of the Fy(a-b-) in persons who had previously been infected with Plasmodium vivax (67.5%). We observed that 102/141 (72.3%) individuals expressing the Fyb antigen had a P. vivax infection, indicating the importance of the Fyb antigen, silenced by a c.1-67T>C mutation in homozygosis, in preventing the P. vivax infection. We showed that the c.1-67T>C mutation in the FY*A did not silence the FY*A expression on RBCs.

Phenotyping of clinically significant blood group antigens among the South Indian donor population

IntroductionData on the prevalence of clinically significant antigens (Rh, Kell, Kidd, Duffy, MNSs, Lewis, P and Lutheran) among the Indian donor population is sparse. ObjectiveThis prospective study was aimed at determining the prevalence of 21 clinically significant antigens for the first time in the South Indian donor population. MethodA total of 672 regular O group blood donors were enrolled for Rh (C,c, E, e) and Kell (K) antigens typing. Of these, 188 donors were typed for other clinically significant antigens (k, Kpa, Kpb, Jka, Jkb, Fya, Fyb, M, N, S, s, P1, Lea, Leb, Lua and Lub). ResultsAntigen frequencies were expressed in percentages. In our study, R1R1 and rr were the most common phenotypes among D+ and D- donors, respectively. Among the Rh antigens, the e antigen was expressed by 97.5% and 100% of D+ and D- donors, respectively. The K antigen was found in only 0.15% of donors. In the Duffy and Kidd blood group system, Fy (a+b+) and Jk (a+b+) were the most frequent phenotypes, respectively. In the MNSs blood group system, M+N+ and S-s+ were the most common phenotypes reported. The Le (a-b+) was found to be the phenotype with the highest prevalence in the Lewis blood group system. The Lu (a-b+) was the only phenotype found in the Lutheran blood group system. ConclusionKnowledge regarding the prevalence of antigens in a given population is essential in developing cost-effective in-house panels and a rare donor registry comprising donors typed negative for a high-frequency antigen or a combination of common multiple antigens.

Instances of Human Genetic Resistance Against Pathogens

This paper will review research on genetic mutations in humans that grant resistance against pathogens. It will describe the characteristics of these genetic traits, which pathogens they grant resistance to, and the mechanism by which these traits provide resistance. It will then discuss the detrimental aspects of these traits, if any, and the potential applications of the genetic resistance mechanisms. Finally, it will cover further research on the genetic trait or pathogen that should be conducted. The following traits will be discussed within this review: sickle cell mutation in the hemoglobin gene and malaria resistance, the Δ32 mutation in the CCR5 gene and HIV resistance, and the erythrocyte silent mutation in the Duffy antigen promoter and malaria resistance. The research conducted on these genetic traits has allowed us to understand more of the pathophysiology of the disease they resist against.

Pichia-Expressed Recombinant D6 and DARC Negatively Affect Cell Migration and Invasion of Breast Cancer Cells

Atypical chemokine receptor proteins are termed ‘decoy proteins’ as their binding to the respective ligands does not lead to a typical signaling pathway but intercepts the action of chemokines. This method of chemokine activity regulation may also function in tumor suppression. D6 and DARC (Duffy Antigen Receptor for Chemokines) have been reported as decoy chemokine receptors in cancer studies. Purified Pichia-expressed D6 and DARC, produced in-house, were used in cell-based studies to test their biological activities. Cell viability tests showed that recombinant D6 and DARC did not affect cell viability significantly, suggesting that they were not involved in breast cancer cell death. Wound healing assays showed that the presence of recombinant D6 or DARC at 10 µg/mL optimally inhibited the migration of breast cancer cells. ELISA showed an inverse relationship between the recombinant proteins and CCL2 levels in the treated cells. Migration assay using Boyden chamber demonstrated the function of the recombinant proteins in inhibiting chemotaxis activity of treated cells. Invasion assay showed the ability of the recombinant proteins in inhibiting the invasion property of treated cells. Comparison of single and combinatorial effects of the recombinant proteins showed that the combination of D6 and DARC at a 1:1 ratio (10 µg/mL) is most effective in reducing CCL2 levels and inhibiting the migration and invasion of treated cells. It was shown that the purified Pichia-expressed recombinant D6 and DARC are the negative regulators of breast cancer cell migration and invasion, and the inhibition effects were greater when they were used in combination.

Red Blood Cell Alloimmunization in Sickle Cell Disease: Advantage of Ethnic Heritage between Donors and Patients in Jeddah, Saudi Arabia

Abstract Introduction/Objective Red blood cell (RBC) transfusion is frequently required for patients with sickle cell disease (SCD). Development of alloantibodies in these patients complicates the blood bank process needed to identify these antibodies and to find compatible RBC units. The rate of alloimmunization has been reported as high as 47% in one study and 34.2% in another study from Eastern region of Saudi Arabia. The purpose of this study was to determine incidence and rate of RBC alloimmunization in the Saudi population in the Western region in SCD. Methods/Case Report A retrospective analysis of the immunohematological and transfusion history of a total of 161 SCD patients was reviewed, of which there 95 males and 66 females. All patients had erythrocytapheresis, ranging from one to 24 full red cell exchange sessions. A total of 490 red cell exchanges were performed and 4,914 units of blood were used. Extended compatibility to RhCcEe and K antigen was performed. Patient who developed alloimmunization to any of RhCcEe and K antigen were matched for Kidd, Duffy and MSN antigens for subsequent RBC requirements. Results (if a Case Study enter NA) The RBC alloimmunization incidence was 18% with a rate of 0.6 antibodies per 100 RBC transfusions. Alloimmunization in females was significantly higher than in the patients. Eighteen (11.2%) female patients demonstrated antibodies as compared to eleven (6.8%) male patients. Twelve patients (7.4%) had a history of at least one alloantibody and 17 (10.6%) had more than one. Antibodies found were directed against E (7.4%), K (5.6%), and D, C, c, S, M, Lea, Jk a, Chido/Rodgers, Fy a. Seven (4.3%) patients also had warm autoantibodies. Conclusion RBC alloimmunization incidence and rate in our study was lower to those reported in less heterogeneous population of donors and patients. Nonetheless, RBC alloimmunization still occurs in patients with SCD, often due to Rh variants or lack of consistency in the application of prophylactic antigen matching between institutions. Therefore, we believe that this rate can still be further reduced if all centers in the region establish transfusion programs to include at least RhCcEe and K phenotypic compatibility and communication mechanisms between major treating centers and transfusion centers in smaller cities to minimize the risks of exposing the patient to different RhCcEe and K phenotype and of developing RBC alloimmunization.

Obesity and the Bidirectional Risk of Cancer and Cardiovascular Diseases in African Americans: Disparity vs. Ancestry.

Cardiovascular disease (CVD) and cancer often occur in the same individuals, in part due to the shared risk factors such as obesity. Obesity promotes adipose inflammation, which is pathogenically linked to both cardiovascular disease and cancer. Compared with Caucasians, the prevalence of obesity is significantly higher in African Americans (AA), who exhibit more pronounced inflammation and, in turn, suffer from a higher burden of CVD and cancer-related mortality. The mechanisms that underlie this association among obesity, inflammation, and the bidirectional risk of CVD and cancer, particularly in AA, remain to be determined. Socio-economic disparities such as lack of access to healthy and affordable food may promote obesity and exacerbate hypertension and other CVD risk factors in AA. In turn, the resulting pro-inflammatory milieu contributes to the higher burden of CVD and cancer in AA. Additionally, biological factors that regulate systemic inflammation may be contributory. Mutations in atypical chemokine receptor 1 (ACKR1), otherwise known as the Duffy antigen receptor for chemokines (DARC), confer protection against malaria. Many AAs carry a mutation in the gene encoding this receptor, resulting in loss of its expression. ACKR1 functions as a decoy chemokine receptor, thus dampening chemokine receptor activation and inflammation. Published and preliminary data in humans and mice genetically deficient in ACKR1 suggest that this common gene mutation may contribute to ethnic susceptibility to obesity-related disease, CVD, and cancer. In this narrative review, we present the evidence regarding obesity-related disparities in the bidirectional risk of CVD and cancer and also discuss the potential association of gene polymorphisms in AAs with emphasis on ACKR1.

Children with Plasmodium vivax infection previously observed in Namibia, were Duffy negative and carried a c.136G\u2009>\u2009A mutation

BackgroundIn a previous study, using a molecular approach, we reported the presence of P. vivax in Namibia. Here, we have extended our investigation to the Duffy antigen genetic profile of individuals of the same cohort with and without Plasmodium infections.MethodsParticipants with P. vivax (n = 3), P. falciparum (n = 23) mono-infections and co-infections of P. vivax/P. falciparum (n = 4), and P. falciparum/P. ovale (n = 3) were selected from seven regions. Participants with similar age but without any Plasmodium infections (n = 47) were also selected from all the regions. Duffy allelic profile was examined using standard PCR followed by sequencing of amplified products. Sequenced samples were also examined for the presence or absence of G125A mutation in codon 42, exon 2.ResultsAll individuals tested carried the − 67 T > C mutation. However, while all P. vivax infected participants carried the c.G125A mutation, 7/28 P. falciparum infected participants and 9/41 of uninfected participants did not have the c.G125A mutation. The exon 2 region surrounding codon 42, had a c.136G > A mutation that was present in all P. vivax infections. The odds ratio for lack of this mutation with P. vivax infections was (OR 0.015, 95% CI 0.001–0.176; p = 0.001).ConclusionWe conclude that P. vivax infections previously reported in Namibia, occurred in Duffy negative participants, carrying the G125A mutation in codon 42. The role of the additional mutation c.136 G > A in exon 2 in P. vivax infections, will require further investigations.

Genotyping of ABO and Duffy blood groups among malaria patients in Thailand.

ABO blood groups have been proposed to influence malaria parasite infection and disease severity in individuals residing in different geographical areas. In Thailand, genetic polymorphisms of blood groups and susceptibility to malaria infection have rarely been investigated. The aim of this study was to assess the genotype frequencies of ABO and Duffy blood groups and susceptibility to malaria infection in two populations residing in malaria-endemic areas of Thailand. 1100 malaria samples and an identical number of samples from healthy subjects were collected from Thai-Malaysian and Thai-Myanmar areas. Genotyping of ABO and Duffy blood groups was performed by sequence specific primer-polymerase chain reaction. The distribution of ABO and Duffy blood groups was similar in malaria-positive and negative subjects. Blood group O was prevalent in both populations followed by blood group B (BO genotype) and A (AO genotype), respectively. In Plasmodium falciparum infections, blood group A frequency was significantly higher in Thai-Malaysian samples (P = 0.042) whereas blood group B frequency was significantly higher in Thai-Myanmar samples (P = 0.022). FY*A/*A frequency was significantly higher in Plasmodium vivax infection (P = 0.036) while FY*A/*B frequency was significantly higher in healthy subjects (P = 0.005). The different ABO blood group frequencies in the two populations may contribute to susceptibility to P. falciparum infection and the high prevalence of FY*A/*A can confer a risk of P. vivax infection. Further research in various ethnic groups is needed to clarify the association between blood groups and pathogenesis of malaria.

Red blood cell frequencies and genetic polymorphisms of various blood grouping systems in the emirati population

AbstractBackground and objectivesData on the frequencies of RBC antigens and their variants in the Arab world are limited. Thus, determining the antigenic profile of the United Arab Emirates (UAE) population by serologic and molecular methods is significant to enhance operational efficiency in donor centres and transfusion services.Study design and methodsThe study is a retrospective retrieval of serologic and genotype data. The serological ABO type data of 30 954 UAE national donors, the serological RHD and RHCE data of 10 036 UAE national donors, and the genotype data of 354 patients and donors of admixed nationalities for determining different blood group systems were retrieved and analysed.ResultsRh D negative (dccee) phenotype in the UAE national donor population is lower compared to the reported Rh D negative phenotype in the European population (6·8% vs. 18%) and there were a high number of variants observed in the patient and donor populations, especially in the RhCE and Duffy blood group systems (12·1% and 59·3%, respectively).ConclusionHigh number of variants and rare blood group profiles were observed and the gene pool of the Emirati nationals, as well as their antigenic frequencies, is an intermediate between the European and African populations rather than the Asian gene pool.

Sequence analysis of Plasmodium vivax Duffy binding proteins reveals the presence of unique haplotypes and diversifying selection in Ethiopian isolates

BackgroundRed blood cell invasion by the Plasmodium vivax merozoite requires interaction between the Duffy antigen receptor for chemokines (DARC) and the P. vivax Duffy-binding protein II (PvDBPII). Given that the disruption of this interaction prevents P. vivax blood-stage infection, a PvDBP-based vaccine development has been well recognized. However, the polymorphic nature of PvDBPII prevents a strain transcending immune response and complicates attempts to design a vaccine.MethodsTwenty-three P. vivax clinical isolates collected from three areas of Ethiopia were sequenced at the pvdbpII locus. A total of 392 global pvdbpII sequences from seven P. vivax endemic countries were also retrieved from the NCBI archive for comparative analysis of genetic diversity, departure from neutrality, linkage disequilibrium, genetic differentiation, PvDBP polymorphisms, recombination and population structure of the parasite population. To establish a haplotype relationship a network was constructed using the median joining algorithm.ResultsA total of 110 variable sites were found, of which 44 were parsimony informative. For Ethiopian isolates there were 12 variable sites of which 10 were parsimony informative. These parsimony informative variants resulted in 10 nonsynonymous mutations. The overall haplotype diversity for global isolates was 0.9596; however, the haplotype diversity was 0.874 for Ethiopia. Fst values for genetic revealed Ethiopian isolates were closest to Indian isolates as well as to Sri Lankan and Sudanese isolates but further away from Mexican, Papua New Guinean and South Korean isolates. There was a total of 136 haplotypes from the 415 global isolates included for this study. Haplotype prevalence ranged from 36.76% to 0.7%, from this 74.2% were represented by single parasite isolates. None of the Ethiopian isolates grouped with the Sal I reference haplotype. From the total observed nonsynonymous mutations 13 mapped to experimentally verified epitope sequences. Including 10 non-synonymous mutations from Ethiopia. However, all the polymorphic regions in Ethiopian isolates were located away from DARC, responsible for junction formation.ConclusionThe results of this study are concurrent with the multivalent vaccine approach to design an effective treatment. However, the presence of novel haplotypes in Ethiopian isolates that were not shared by other global sequences warrant further investigation.

Renal allograft DARCness in subclinical acute and chronic active ABMR.

SummaryGene expression profiling of renal allograft biopsies revealed the Duffy antigen receptor for chemokines (DARC) as being strikingly upregulated in antibody‐mediated rejection (ABMR). DARC has previously been shown to be associated with endothelial injury. This study aimed at assessing the value of DARC immunohistochemistry as diagnostic marker in ABMR. The study was performed on 82 prospectively collected biopsies of a clinically well‐defined population (BORTEJECT trial, NCT01873157) of DSA‐positive patients with gene expression data available for all biopsies. Diagnostic histologic assessment of biopsies was performed according to the Banff diagnostic scheme. DARC expression was focally accentuated, on peritubular capillaries (PTC) mostly in areas of interstitial fibrosis and/or inflammation. DARC positivity was associated with diagnosis of ABMR and correlated with DARC gene expression levels detected by microarray analysis. Still, as previously described, a substantial number of biopsies without signs of rejection showed DARC‐positive PTC. We did not observe significantly reduced graft survival in cases showing histologic signs of ABMR and being DARC‐positive, as compared to DARC‐negative ABMR. In summary, the upregulation of DARC, detected by immunohistochemistry, is associated with but not specific for ABMR. We did not observe reduced graft survival in DARC‐positive patients.

Genetic Polymorphism of Antigens in Twelve Rare Blood Group Systems of Li Nationality in Hainan Province

To explore the distribution characteristics of main antigen gene frequencies of Duffy,Diego,Kidd,Dombrock,MNS,Lutheran,Kell,Colton,Scianna,Yt,Knops and Indian in red blood cell blood group system of Li nationality in Hainan Province. Antigens in twelve rare blood group systems of 214 Li people in Hainan Province were genotyped and analyzed by polymerase chain reaction-sequence specific primers (PCR-SSP). The gene frequency of antigens in twelve rare blood group systems of 214 Li people in Hainan Province including: the gene frequency of Duffy blood group system: fya=0.9556，fyb=0.0444；the gene frequency of Diego blood group system: Dia=0.0678，Dib=0.9322；the gene frequency of Kidd blood group system：JKa=0.4533，JKb=0.5467；the gene frequency of Dombrock blood group system：DOa=0.1051，DOb=0.8949；the gene frequency of MNS blood group system：M=0.8131，N=0.1869,S=0.0327，s=0.9673，Mur+=0.5748，Mur-=0.4252；the gene frequency of Lutheran blood group system：AUa=0.8318，AUb=0.1682；the Kell, Colton, Scianna, Yt, Knops and Indian blood type systems showed a monomorph and the genotype was kk, coacoa, Sc1Sc1, YtaYta, KnaKna and InbInb. The observed and expected genotype values in twelve rare blood group systems of Li nationality in Hainan province were obeyed by the Hardy-Weinberg genitic rules. The difference between the observed and expectated values of the Kidd blood group system showed significant differences（χ2=17.1946，P=0.0002）. The genetic distribution and genetic status in twelve rare blood group systems of Li nationality in Hainan Province are relatively stable. The gene distribution of Duffy, Diego, Kidd, Drombrock, MNS and Lutheran blood group systems are polymorphic and show unique distribution characteristics compared with other regions and different nationalities. The gene frequency distribution of Kell、Colton、Scianna、Yt、Knops、Indian blood group systems are monomorphic.

Distinctive genetic structure and selection patterns in Plasmodium vivax from South Asia and East Africa

Despite the high burden of Plasmodium vivax malaria in South Asian countries, the genetic diversity of circulating parasite populations is not well described. Determinants of antimalarial drug susceptibility for P. vivax in the region have not been characterised. Our genomic analysis of global P. vivax (n = 558) establishes South Asian isolates (n = 92) as a distinct subpopulation, which shares ancestry with some East African and South East Asian parasites. Signals of positive selection are linked to drug resistance-associated loci including pvkelch10, pvmrp1, pvdhfr and pvdhps, and two loci linked to P. vivax invasion of reticulocytes, pvrbp1a and pvrbp1b. Significant identity-by-descent was found in extended chromosome regions common to P. vivax from India and Ethiopia, including the pvdbp gene associated with Duffy blood group binding. Our investigation provides new understanding of global P. vivax population structure and genomic diversity, and genetic evidence of recent directional selection in this important human pathogen.

The effect of erythrocyte transfusion on macrophage pyroptosis and inflammation in a sepsis model.

Sepsis is one of most common causes of death in the intensive care unit (ICU) due to infection and inflammation. The Duffy antigen receptor for chemokines (DARC) regulates pro-inflammatory cytokines, thus playing an important role in inflammation. This study aimed to elucidate the correlation among erythrocyte transfusion, macrophage pyroptosis and inflammation in the progression of sepsis. Alanine aminotransferase (ALT/GPT) activity was measured with the ALT/GPT activity measurement kit (Jiancheng Bio, Nanjing, China) according to the kit manual. The ET-1 concentration was measured with enzyme-linked immunosorbent assay (ELISA) using the endothelin-1 (ET-1) measurement kit (Jiancheng Bio) according to the kit manual. Apoptosis was evaluated using flow cytometry-based Annexin V staining assay. The cells were collected using centrifugation and resuspended in binding buffer. Ultrastructural analysis of pyroptotic body, the levels of interleukin (IL)-1β, IL-18, IL-33, MIP-2, CXCL8, reactive oxygen species (ROS), and LTB4 were measured with ELISA. Our results showed that septic rats had impaired hepatic function and ET-1 levels. Erythrocyte transfusion upregulated DARC expression in the sepsis model. Erythrocyte transfusion also affected pyroptosis in macrophages, reduced the production of inflammatory cytokines, such as IL-1β, IL-18 and IL-33, and alleviated cytotoxicity in the sepsis model. Erythrocyte transfusion may function as a therapeutic tool against sepsis by regulating pyroptosis, inflammation and cytotoxicity.

Contrasting epidemiology and genetic variation of Plasmodium vivax infecting Duffy-negative individuals across Africa

ObjectivesPlasmodium vivax malaria was thought to be rare in Africans who lack the Duffy blood group antigen expression. However, recent studies indicate that P. vivax can infect Duffy-negative individuals and has spread into areas of high Duffy negativity across Africa. Our study compared epidemiological and genetic features of P. vivax between African regions. MethodsA standardized approach was used to identify and quantify P. vivax from Botswana, Ethiopia, and Sudan, where Duffy-positive and Duffy-negative individuals coexist. The study involved sequencing the Duffy binding protein (DBP) gene and inferring genetic relationships among P. vivax populations across Africa. ResultsAmong 1215 febrile patients, the proportions of Duffy negativity ranged from 20–36% in East Africa to 84% in southern Africa. Average P. vivax prevalence among Duffy-negative populations ranged from 9.2% in Sudan to 86% in Botswana. Parasite density in Duffy-negative infections was significantly lower than in Duffy-positive infections. P. vivax in Duffy-negative populations were not monophyletic, with P. vivax in Duffy-negative and Duffy-positive populations sharing similar DBP haplotypes and occurring in multiple, well-supported clades. ConclusionsDuffy-negative Africans are not resistant to P. vivax, and the public health significance of this should not be neglected. Our study highlights the need for a standardized approach and more resources/training directed towards the diagnosis of vivax malaria in Africa.

Rapidly freeze-dried human red blood cells for pre-transfusion alloantibody testing reagents.

Prior to transfusion of red blood cells (RBCs), recipients must be tested for the presence of alloantibodies to avoid immune complications. Liquid-preserved reagent RBCs with known blood group antigen phenotypes are used for testing. However, these reagents have practical constraints, including limited shelf-life and require constant refrigeration. To address these issues, we explore the effects of rapid freeze-drying conditions with trehalose cryoprotectant (0.1-1M concentrations) on human RBCs and storage of freeze-dried RBCs (FDRBCs) at room temperature (RT) for up to 12 months. We report that rapid freeze-drying of RBCs for 2.5hr with 0.5M trehalose achieves recoverable cells with near-normal morphological shape, although size-reduced. The FDRBCs are metabolically active and functional in antibody-agglutination tests by the column agglutination test (CAT) for ABO and Rhesus-D blood group antigens. Expression of the Duffy blood group protein (CD234) decreases by 50% after freeze-drying RBCs. The initial recovery rate is ≤25%; however, 43% of these FDRBCs are still recoverable after RT storage for 12 months. In this proof-of-principle study, we show that rapid freeze-drying can stabilize RBCs. Further refinements to improve the recovery rate and preservation of antigenic epitopes will make FDRBCs a practical alternative source of reagent RBCs for pre-transfusion alloantibody identification.

High frequency of the Duffy-negative genotype and absence of Plasmodium vivax infections in Ghana

BackgroundRecent studies from different malaria-endemic regions including western Africa have now shown that Plasmodium vivax can infect red blood cells (RBCs) and cause clinical disease in Duffy-negative people, though the Duffy-negative phenotype was thought to confer complete refractoriness against blood invasion with P. vivax. The actual prevalence of P. vivax in local populations in Ghana is unknown and little information is available about the distribution of Duffy genotypes. The aim of this study was to assess the prevalence of P. vivax in both asymptomatic and symptomatic outpatients and the distribution of Duffy genotypes in Ghana.MethodsDNA was extracted from dried blood spots (DBS) collected from 952 subjects (845 malaria patients and 107 asymptomatic persons) from nine locations in Ghana. Plasmodium species identification was carried out by nested polymerase chain reaction (PCR) amplification of the small-subunit (SSU) rRNA genes. For P. vivax detection, a second PCR of the central region of the Pvcsp gene was carried out. Duffy blood group genotyping was performed by allele-specific PCR to detect the presence of the FYES allele.ResultsNo cases of P. vivax were detected in any of the samples by both PCR methods used. Majority of infections (542, 94.8%) in the malaria patient samples were due to P. falciparum with only 1 infection (0.0017%) due to Plasmodium malariae, and 2 infections (0.0034%) due to Plasmodium ovale. No case of mixed infection was identified. Of the samples tested for the FYES allele from all the sites, 90.5% (862/952) had the FYES allele. All positive samples were genotyped as FY*B-33/FY*B-33 (Duffy-negative homozygous) and therefore classified as Fy(a−b−).ConclusionsNo cases of P. vivax were detected by both PCRs and majority of the subjects tested carried the FYES allele. The lack of P. vivax infections observed can be attributed to the high frequency of the FYES allele that silences erythroid expression of the Duffy. These results provide insights on the host susceptibility for P. vivax infections that had not been investigated in Ghana before.

An open-source python library for detection of known and novel Kell, Duffy and Kidd variants from exome sequencing.

Next generation sequencing (NGS) has promising applications in transfusion medicine. Exome sequencing (ES) is increasingly used in the clinical setting, and blood group interpretation is an additional value that could be extracted from existing data sets. We provide the first release of an open-source software tailored for this purpose and describe its validation with three blood group systems. The DTM-Tools algorithm was designed and used to analyse 1018 ES NGS files from the ClinSeq® cohort. Predictions were correlated with serology for 5 antigens in a subset of 108 blood samples. Discrepancies were investigated with alternative phenotyping and genotyping methods, including a long-read NGS platform. Of 116 genomic variants queried, those corresponding to 18 known KEL, FY and JK alleles were identified in this cohort. 596 additional exonic variants were identified KEL, ACKR1 and SLC14A1, including 58 predicted frameshifts. Software predictions were validated by serology in 108 participants; one case in the FY blood group and three cases in the JK blood group were discrepant. Investigation revealed that these discrepancies resulted from (1) clerical error, (2) serologic failure to detect weak antigenic expression and (3) a frameshift variant absent in blood group databases. DTM-Tools can be employed for rapid Kell, Duffy and Kidd blood group antigen prediction from existing ES data sets; for discrepancies detected in the validation data set, software predictions proved accurate. DTM-Tools is open-source and in continuous development.

Plasmodium vivax Infections Detected in a Large Number of Febrile Duffy-Negative Africans in Dschang, Cameroon.

The Duffy blood group is a critical receptor for Plasmodium vivax (P. vivax) invasion of red blood cells, and consequently, P. vivax infections were considered rare in sub-Saharan Africa where the prevalence of Duffy-negativity is high. However, recently, P. vivax infections have been found in Duffy-negative Africans throughout the malaria transmission area of sub-Saharan Africa, raising important questions concerning the molecular composition of these P. vivax clones and the red blood cell receptors that facilitate their invasion. Here, we describe an unusually high number of P. vivax infections in febrile Duffy-negative Africans in Dschang, Cameroon (177 of 500 outpatients), as compared with Santchou (two of 400 outpatients) and Kyé-ossi (two of 101 outpatients), in other areas in Cameroon. In the discussion, we speculate on the possible reasons why Dschang might account for the unusually large numbers of P. vivax infections in Duffy-negative individuals living there.