Browse the corpus

The Duffy blood group system, regulated by the ACKR1 gene, includes the key antigens Fya and Fyb, which are expressed on red blood cells as well as on the linings of blood vessels, lungs, kidney tubules, and Purkinje cells in the brain. These antigens function as chemokine receptors, which are vital in modulating inflammation and immune responses. Antibodies directed against Duffy antigens can cause hemolytic transfusion reactions and hemolytic disease of the fetus and newborn. The Duffy-null phenotype, characterized by the absence of both Fya and Fyb antigens, protects against Plasmodium vivax but has also been associated with increased susceptibility to certain infections, such as HIV. Understanding and recognizing a patient’s Duffy status is essential to ensure safe transfusion practices, assess prenatal risk, and guide personalized care. This activity reviews the Duffy blood group system and its clinical implications in transfusion medicine, hematology, and infectious diseases. This activity also explores the genetic diversity and immunological function of Duffy antigens, including their roles in immune modulation and malaria resistance. In addition, this activity also helps healthcare professionals integrate laboratory findings into clinical practice to support safer, more informed decision-making and promote personalized, equitable healthcare delivery. This activity also emphasizes the importance of interprofessional collaboration among healthcare providers to develop skills in interpreting Duffy antigen testing, managing transfusion-related complications, and applying this knowledge to various clinical scenarios. Objectives: Identify the key components of the Duffy blood group system, including the Fya and Fyb antigens and their role in immune response. Implement appropriate transfusion protocols based on a patient’s Duffy antigen status to minimize the risk of hemolytic transfusion reactions. Select appropriate laboratory tests to evaluate Duffy antigen status and interpret results in clinical practice. Collaborate with the interprofessional healthcare team to ensure safe transfusion practices and accurate risk assessment in patients with different Duffy phenotypes. Access free multiple choice questions on this topic.

Blood group antigens are substances found on the surface of red blood cells (RBCs) that serve as markers, distinguishing different blood types. Common blood group antigens include the ABO system, the Rhesus (Rh) factor, Duffy, and Kell. The Duffy blood group system is determined by the ACKR1 gene (OMIM 613665), which is located on chromosome 1q23.2.[1] The 2 main codominant alleles, FY*A and FY*B, produce the Fya and Fyb antigens, which are expressed on the surface of RBCs, vasculature endothelial cells, alveolar epithelial cells, collecting tubules in the kidneys, and the surface of Purkinje cells in the brain. Duffy antigens are absent on platelets, lymphocytes, monocytes, and granulocytes.[2][3] Single-nucleotide differences in the ACKR1 coding region result in a change in a single amino acid, which determines the presence of the Fya and Fyb antigens. Fya contains a guanine at nucleotide 125 and a glycine at amino acid 42. Alternatively, Fyb has an adenine at nucleotide 125 and an aspartate at amino acid 42.[4] Patients lacking Fya and Fyb antigens are considered Duffy-null. These individuals are typically heterozygous for a genetic variation, rs2814778-C (c.-67T>C), in the ACKR1 promoter region, which results in the loss of Duffy antigens on the surface of RBCs without affecting their expression on other cells. In most Duffy-null individuals, a mutation in the FY*B allele, sometimes referred to as FY*BES or the erythrocyte silent allele, specifically the 67T>C mutation (or position 46, depending on the numbering system) near the gene's transcription initiation site, causes this phenotype. This mutation disrupts a binding site for the erythroid transcription factor GATA1, which is crucial for expressing the ACKR1 gene in erythroid cells. This mutation prevents the expression of Duffy glycoproteins on erythrocytes while allowing the expression of Fyb on nonerythroid cells.[4] Rarely, the mutation may also involve the FY*A allele.

Patients lacking Fya and Fyb antigens are considered Duffy-null. These individuals are typically heterozygous for a genetic variation, rs2814778-C (c.-67T>C), in the ACKR1 promoter region, which results in the loss of Duffy antigens on the surface of RBCs without affecting their expression on other cells. In most Duffy-null individuals, a mutation in the FY*B allele, sometimes referred to as FY*BES or the erythrocyte silent allele, specifically the 67T>C mutation (or position 46, depending on the numbering system) near the gene's transcription initiation site, causes this phenotype. This mutation disrupts a binding site for the erythroid transcription factor GATA1, which is crucial for expressing the ACKR1 gene in erythroid cells. This mutation prevents the expression of Duffy glycoproteins on erythrocytes while allowing the expression of Fyb on nonerythroid cells.[4] Rarely, the mutation may also involve the FY*A allele. The Duffy antigens, also known as the atypical chemokine receptor 1 (ACKR1), are glycoproteins that function as chemokine receptors. They bind to chemokines released during inflammation and attract immune system cells to areas of damage. These chemokines include acute inflammation (C-X-R) and chronic inflammation (C-C) chemokines, interleukin (IL)-8, and regulated on activation, normal T expressed and secreted (RANTES). The ACKR1, previously the Duffy antigen receptors for cytokines (DARC) or CD234, is the primary attachment site for the malarial parasite Plasmodium vivax. Patients who are phenotypically Fy(a−b−) are resistant to infection. Duffy Antibodies Although Fya and Fyb are the main determinants of the Duffy system, a total of 5 antigens are present in the Duffy blood group system: Fya, Fyb, Fy3, Fy5, and Fy6.[5][6][7] Anti-Fya and anti-Fyb are the most clinically significant antibodies. These antibodies are the leading causes of immediate or delayed hemolytic transfusion reactions (HTRs). Anti-Fy3 is a less common cause of delayed HTRs. Anti-Fya is the most common cause of hemolytic disease of the fetus and newborn (HDFN), whereas anti-Fy3 and anti-Fyb are uncommon causes of HDFN.[8]

Although Fya and Fyb are the main determinants of the Duffy system, a total of 5 antigens are present in the Duffy blood group system: Fya, Fyb, Fy3, Fy5, and Fy6.[5][6][7] Anti-Fya and anti-Fyb are the most clinically significant antibodies. These antibodies are the leading causes of immediate or delayed hemolytic transfusion reactions (HTRs). Anti-Fy3 is a less common cause of delayed HTRs. Anti-Fya is the most common cause of hemolytic disease of the fetus and newborn (HDFN), whereas anti-Fy3 and anti-Fyb are uncommon causes of HDFN.[8] Antibodies against Duffy blood group antigens are primarily immunoglobulin G (IgG), and IgM type is uncommon. These antibodies typically develop following exposure to Duffy antigens during blood transfusions, pregnancy, or organ transplantation. Anti-Fya antibodies are the most common among Duffy antibodies.[9][10] Most Duffy antibodies react at body temperature, which can cause hemolysis and make them clinically significant. These antibodies can lead to both acute and delayed types of HTRs and HDFN.[11][12] The Duffy blood group system demonstrates a dosage phenomenon, where individuals with a homozygous phenotype have more antigens per RBC than those with a heterozygous phenotype. As a result, Duffy antibodies react more strongly in patients with homozygous phenotypes, Fy(a−b+) or Fy(a+b−), than in those with the heterozygous phenotype Fy(a+b+).[13] Duffy Phenotypes The predominant Duffy phenotypes are Fy(a+b−), Fy(a+b+), Fy(a−b+), and Fy(a−b−). The Fya and Fyb antigens are most commonly found in White patients and patients of Asian descent, and least commonly in Black patients. Additionally, 67% of Black individuals have the Duffy-null phenotype, which is rare in White patients (see the Table below).[14][15][16] An additional minor Duffy phenotype, the Fyx or [Fy(b+x)], is a variant caused by a missense mutation in ACKR1. The FY*X allele encodes the Fyb antigen and weakly expresses Fyb, which may not be detected by anti-Fyb. Table Table. Worldwide Duffy Blood Group Antigenic Frequencies .

The Duffy blood group system, encoded by the ACKR1 gene, includes antigens expressed on RBCs and other tissues, such as endothelial cells. The primary antigens, Fya and Fyb, are determined by a single-nucleotide variation and are clinically significant in transfusion medicine, as antibodies against them can lead to HTRs and HDFN. Beyond transfusion compatibility, Duffy antigens, also called ACKR1, are crucial in modulating inflammatory responses. ACKR1 is a non-signaling chemokine receptor that binds many proinflammatory chemokines, including CCL2, CCL5, and IL-8. By functioning as a "chemokine sink," ACKR1 sequesters excess chemokines, thereby regulating their availability and controlling the extent of leukocyte recruitment to sites of inflammation. ACKR1 also facilitates the transcytosis of chemokines across the endothelium, aiding neutrophil migration into tissues, such as the lungs, during respiratory inflammation. This regulatory role makes ACKR1 crucial in balancing an effective immune response and excessive inflammation. For example, altered Duffy antigen expression is associated with varying responses in conditions such as malaria, HIV infection, and possibly SARS-CoV-2, where inflammation is central to disease severity. Understanding the function of Duffy antigens in immune regulation and transfusion medicine is essential for optimizing patient care, especially in individuals with the Duffy-null phenotype.

Beyond transfusion compatibility, Duffy antigens, also called ACKR1, are crucial in modulating inflammatory responses. ACKR1 is a non-signaling chemokine receptor that binds many proinflammatory chemokines, including CCL2, CCL5, and IL-8. By functioning as a "chemokine sink," ACKR1 sequesters excess chemokines, thereby regulating their availability and controlling the extent of leukocyte recruitment to sites of inflammation. ACKR1 also facilitates the transcytosis of chemokines across the endothelium, aiding neutrophil migration into tissues, such as the lungs, during respiratory inflammation. This regulatory role makes ACKR1 crucial in balancing an effective immune response and excessive inflammation. For example, altered Duffy antigen expression is associated with varying responses in conditions such as malaria, HIV infection, and possibly SARS-CoV-2, where inflammation is central to disease severity. Understanding the function of Duffy antigens in immune regulation and transfusion medicine is essential for optimizing patient care, especially in individuals with the Duffy-null phenotype. Effective healthcare regarding Duffy blood group antigens requires clinical expertise, strategic planning, interprofessional communication, and coordinated care among healthcare professionals. Physicians and advanced practitioners must recognize the clinical significance of Duffy antigens, particularly in the context of transfusion safety, susceptibility to infectious diseases, and the risk of HDFN. Nurses play a crucial role in verifying the compatibility of the patient's identity and blood type with the donor blood. They also monitor for transfusion reactions and educate patients about potential adverse effects, as well as the need for Duffy antigen-negative blood in future transfusions for those with the Duffy-null phenotype. Blood bank personnel are essential to patient safety by performing blood typing, antibody identification, and crossmatching to ensure compatibility between donor and recipient blood. Pharmacists offer guidance on safe medication use and assist in supporting transfusion protocols.

Effective healthcare regarding Duffy blood group antigens requires clinical expertise, strategic planning, interprofessional communication, and coordinated care among healthcare professionals. Physicians and advanced practitioners must recognize the clinical significance of Duffy antigens, particularly in the context of transfusion safety, susceptibility to infectious diseases, and the risk of HDFN. Nurses play a crucial role in verifying the compatibility of the patient's identity and blood type with the donor blood. They also monitor for transfusion reactions and educate patients about potential adverse effects, as well as the need for Duffy antigen-negative blood in future transfusions for those with the Duffy-null phenotype. Blood bank personnel are essential to patient safety by performing blood typing, antibody identification, and crossmatching to ensure compatibility between donor and recipient blood. Pharmacists offer guidance on safe medication use and assist in supporting transfusion protocols. Effective communication among healthcare team members, including laboratory staff, clinicians, and pharmacists, is crucial for accurately interpreting blood typing and antibody screens while maintaining consistent documentation. Coordinated care is vital in situations such as prenatal care, chronic transfusion management, or surgical preparation, where knowledge of a patient's Duffy status can significantly impact outcomes. In such cases, collaboration with specialists in hematology, infectious disease, obstetrics, pediatrics, neonatology, and blood banking ensures proper planning and intervention. By collaborating and leveraging shared expertise, healthcare teams can enhance patient safety, reduce the risk of adverse events such as HTRs, and deliver more patient-centered care.

The Duffy blood group system requires coordinated care from nursing, allied health, and interprofessional healthcare teams. Nurses ensure safe transfusions by administering Duffy antigen-negative blood to patients with anti-Fy antibodies, preventing hemolytic reactions, and educating patients on post-transfusion care. Allied health professionals conduct phenotyping and antibody screening to identify compatible blood units and assess malaria susceptibility. The interprofessional team collaborates on targeted treatments, enhancing transfusion safety and improving patient outcomes through timely, evidence-based care.

Effective management of the Duffy blood group system in clinical settings depends on the collaborative efforts of nursing, allied healthcare professionals, and the interprofessional healthcare team to ensure patient safety and optimize outcomes. Nurses are crucial in monitoring patients with Duffy antibodies, ensuring that Duffy antigen-negative, crossmatch-compatible blood units are used during transfusions to prevent HTRs or HDFN. They also educate patients on the importance of adhering to transfusion protocols and monitor for delayed reactions, which can occur weeks after transfusion due to the body's unique immunogenicity. Allied healthcare professionals, such as laboratory technologists, play a key role in accurately identifying Duffy phenotypes and antibodies through serological and molecular testing, providing essential data for informed treatment decisions. The interprofessional healthcare team, including physicians, advanced practice providers, pharmacists, and transfusion specialists, uses this information to tailor interventions, such as intrauterine transfusions for HDFN or selecting Duffy-negative blood for patients with the Duffy-null phenotype. This coordinated approach supports accurate diagnostics, safe transfusion practices, and improved patient outcomes across a range of clinical scenarios involving the Duffy blood group system.