Red cell antigens: Structure and function

Blood Group Type Association with Head and Neck Cancer

Background: We conducted an analysis to check whether the ABO blood group impacts the susceptibility or protection against different types of head and neck cancers. Method: We analyzed the medical records of 61,899 cancer patients from “Prof. Dr. Alexandru Trestioreanu” Institute of Oncology from Bucharest, along with the corresponding blood group type. Data were scraped using Python. For analysis, we used Chi-square test. Results: The blood group count was A (245, 45.12%) followed by 0 (160, 24.66%), B (110, 20.26%), and AB (28, 5.16%). Hypopharyngeal cancer was associated with B group, oral cavity cancer was associated with a lower risk in patients with B group while AB patients had a higher risk for oral cavity cancer (χ² = 36.136, df = 18, p = 0.007). Conclusion: Blood group B is associated with an increased incidence for hypopharyngeal cancer, whereas, for the oral cavity, was associated lower incidence. Blood antigen A is associated with a higher risk of oral cavity cancer development, independent of B blood antigen.

Distribution of Kell antigens K, k, Kpa, and Kpb among blood donors in Jeddah city of Western Saudi Arabia

CONTEXT:

Kell blood group system is considered as the third clinically significant blood group in blood transfusion due to the highly immunogenetic of their antigens. No data are available regarding the frequencies of the Kell blood group antigens in Jeddah city. Knowledge of the antigen and phenotype frequencies is crucial to assess the risk of alloimmunization and to guide the probability of finding antigen-negative donor blood, which can be useful when blood transfusion is required for a patient who has multiple red cell alloantibodies.

AIMS:

The aim of this study was to determine the distribution of Kell blood group: K, k, Kp^a, and Kp^b antigens and phenotypes among blood donors in Jeddah city, western Saudi Arabia, to improve the transfusion services in the area.

SUBJECTS AND METHODS:

Seven hundred and fifty-eight blood samples from blood donors were used in the study. The samples were collected from different national blood bank centers in Jeddah city hospitals. Kell antigens were typed through gel card method using commercial antisera.

STATISTICAL ANALYSIS USED:

The gathered data were analyzed using the SPSS program. Frequency and crosstab tests were completed to achieve the objectives of the current study.

RESULTS:

The most frequent Kell phenotype in this study was Kp^(a−b+), followed by K−k+, K+k+, and then Kp^(a+b+), and the less frequent was K+k−. K−k− and Kp^(a+b−) phenotypes were not observed in studied donors.

CONCLUSIONS:

This study is the first report to determine the frequency of Kell antigens and phenotypes among blood donors in Jeddah city. These results appear to be useful in providing better care for patients by implementing tests that should become a routine in blood banks. The Kell system is very important in transfusion medicine practice.

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 (0.1-1 M 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 2.5 hr with 0.5 M 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.

Pharmacogenomics with red cells: a model to study protein variants of drug transporter genes

The PharmacoScan pharmacogenomics platform screens for variation in genes that affect drug absorption, distribution, metabolism, elimination, immune adverse reactions and targets. Among the 1,191 genes tested on the platform, 12 genes are expressed in the red cell membrane: ABCC1, ABCC4, ABCC5, ABCG2, CFTR, SLC16A1, SLC19A1, SLC29A1, ATP7A, CYP4F3, EPHX1 and FLOT1. These genes represent 5 ATP-binding cassette proteins, 3 solute carrier proteins, 1 ATP transport protein and 3 genes associated with drug metabolism and adverse drug reactions. Only ABCG2 and SLC29A1 encode blood group systems, JR and AUG, respectively. We propose red cells as an ex vivo model system to study the effect of heritable variants in genes encoding the transport proteins on the pharmacokinetics of drugs. Altered pharmacodynamics in red cells could also cause adverse reactions, such as haemolysis, hitherto unexplained by other mechanisms.

Silent red blood cell autoantibodies: Are they naturally occurring or an effect of tolerance loss for a subsequent autoimmune process?

Unexpected anti-red blood cell (RBC) alloantibodies are routinely investigated in immunohematology and blood banking since their existence in pregnant women may induce haemolytic disease of the foetus and newborn, and their presence in donors may induce haemolytic transfusion reactions or hyperacute rejection in solid organ transplantation. Unexpected anti-RBC alloantibodies may target antigens of the most blood types excluding the expected antibodies targeting the ABO antigens. Their incidence in humans was originally linked to alloimmunization events such as blood transfusions, transplants, or pregnancies. But later, many findings revealed their existence in pathogenic processes such as malignancies, infections, and autoimmune diseases; and usually (but not always) associated to autoimmune haemolytic anaemia (AIHA). Nevertheless, unexpected anti-RBC autoantibodies are also occasionally found in healthy individuals in the absence of AIHA and with no history of alloimmunization or the associated pathologic processes. Hence, they are generally known as non-clinically significant, are excluded for typification and called "silent red blood cell autoantibodies (SRBCAA)". This review highlights evidence related to genetic predisposition, molecular mimicry, immune dysregulation, and immune tolerance loss surrounding the existence of anti-RBC antibodies, describing the presence of SRBCAA as possible early witnesses of the development of autoimmune diseases.

Temporal sequence of the human RBCs' vesiculation observed in nano-scale with application of AFM and complementary techniques

Based on the multimodal characterization of human red blood cells (RBCs), the link between the storage-related sequence of the nanoscale changes in RBC membranes in the relation to their biochemical profile as well as mechanical and functional properties was presented. On the background of the accumulation of RBCs waste products, programmed cell death and impaired rheological properties, progressive alterations in the RBC membranes including changes in their height and diameter as well as the in situ characterization of RBC-derived microparticles (RMPs) on the RBCs surface were presented. The advantage of atomic force microscopy (AFM) in RMPs visualization, even at the very early stage of vesiculation, was shown based on the results revealed by other reference techniques. The nanoscale characterization of RMPs was correlated with a decrease in cholesterol and triglycerides levels in the RBC membranes, proving the link between the lipids leakage from RBCs and the process of vesiculation.

Antibody-mediated immunosuppression can result from RBC antigen loss independent of Fcγ receptors in mice

BACKGROUND

Anti-RhD administration can prevent de novo anti-RhD formation following RhD+ red blood cell (RBC) exposure, termed antibody-mediated immunosuppression (AMIS). Recent studies suggest that AMIS may occur through target antigen alterations, known as antigen modulation. However, studies suggest that AMIS may occur independent of antigen modulation. In particular, AMIS to RBCs that transgenically express the fusion hen egg lysozyme-ovalbumin-Duffy (HOD) antigen have been shown to occur independent of activating Fcγ receptors (FcγRs) thought to be required for antigen modulation. Therefore, we sought to determine the mechanism behind AMIS following HOD RBC exposure.

STUDY DESIGN AND METHODS

Following transfer of HOD RBCs into wild-type or FcγR-chain knockout recipients in the presence or absence of monoclonal anti-hen egg lysozyme (HEL) antibody, individually or in combination, HOD antigen levels and anti-HOD antibody formation were examined.

RESULTS

Our results demonstrate that anti-HEL antibodies individually or in combination suppressed anti-HOD IgM, which correlated with the rate of detectable decrease in HEL on HOD RBCs. Furthermore, exposure to anti-HEL antibodies alone or in combination equally suppressed anti-HOD IgG formation. Unexpectedly, combination or individual anti-HEL antibodies induced AMIS and antigen modulation in an FcγR-independent manner. Pre-exposure of HOD RBCs to anti-HEL antibodies reduced antigen levels and suppressed anti-HOD antibody formation following HOD RBC exposure.

CONCLUSION

These results suggest that antibody-mediated antigen modulation may reflect a mechanism of AMIS that can occur independent of activating FcγRs and may provide a surrogate to identify antibodies capable of inducing AMIS against different RBC antigens.

Complement serves as a switch between CD4+ T cell-independent and -dependent RBC antibody responses

RBC alloimmunization represents a significant immunological challenge for patients requiring lifelong transfusion support. The majority of clinically relevant non-ABO(H) blood group antigens have been thought to drive antibody formation through T cell-dependent immune pathways. Thus, we initially sought to define the role of CD4+ T cells in formation of alloantibodies to KEL, one of the leading causes of hemolytic transfusion reactions. Unexpectedly, our findings demonstrated that KEL RBCs actually possess the ability to induce antibody formation independent of CD4+ T cells or complement component 3 (C3), two common regulators of antibody formation. However, despite the ability of KEL RBCs to induce anti-KEL antibodies in the absence of complement, removal of C3 or complement receptors 1 and 2 (CR1/2) rendered recipients completely reliant on CD4+ T cells for IgG anti-KEL antibody formation. Together, these findings suggest that C3 may serve as a novel molecular switch that regulates the type of immunological pathway engaged following RBC transfusion.

A retrospective study: ABO and Rh phenotype blood group distribution among blood donors in H.N.B. Base Hospital, Srinagar, Uttarakhand, India

Objective:

To determine the prevalence of ABO and Rh blood groups based on the antigenic presence on the surface of red blood cells with respect to gender and calculate allele frequency of the blood groups. Globally, approximately 700 type red cell antigens have been identified till now. ABO and Rh blood groups play an important role in the process of blood transfusion, resolving certain medicolegal issues, parental testing, and various genetic studies.

Methods:

This study was conducted in H.N.B. Base Hospital, Srinagar, Uttarakhand, from January 2012 to December 2016. Relevant data of blood donors were collected from blood bank department of the hospital. Blood grouping was conducted using commercially available standard monoclonal antisera applying test tube and column agglutination techniques.

Results:

Out of 9883 individuals, 9333 (92.4%) were males and 750 (7.6%) were female individuals. The most common blood group found was B (31.68%) and least common being AB (11.70%). The prevalence of Rhesus positive and negative distribution in the present studied population was found as 93.51% and 6.49%, respectively. Overall, male ABO group pattern found was shown by formula B > A > O > AB which was similar among Rh-positive male individuals while Rh-negative males' pattern was found as A > B = O > AB. In females, ABO group pattern was B > O > A > AB which was similar to Rh-positive female pattern while differs in Rh negative. The estimated allele frequencies were found as 0.2403, 0.2475, and 0.5122 for I^A (p), I^B (q), and I^O (r), respectively.

Conclusion:

The most common blood group found among the Gharwali donors was B positive while the least common was AB negative, which plays an important contribution for making government policies to develop National Health Program.