Decreased rate of blood donors with high ABO antibody titers in Japan and the underlying factors: Comparisons between 2010 and 2021.

BACKGROUND AND OBJECTIVES: Previously (2007), it was reported that ABO antibody titers in Japanese blood donors had decreased significantly compared to 20 years before. Here we evaluated whether further decrease of antibody titers had occurred in recent years, and the potential factors associated with changes in antibody titers. MATERIALS AND METHODS: Serum/plasma from random blood donors in 2010 and 2021 (2010: 3369, 2021: 5796 donors) was classified into low, middle, and high ABO antibody titers according to the reactivity of diluted serum/plasma (2.5-fold and 20-fold) by an automated microplate system. The rates of low/high titer in the two periods were compared. Logistic regression and age-gender-BMI subgroup analyses were conducted to identify the factors that contributed to changes in antibody titers. RESULTS: Compared to 2010, the rate of donors with high ABO antibody titers was　decreased in 2021 for both anti-A and anti-B (anti-A, 2010: 23.8%, 2021: 19.3%; anti-B, 2010: 23.8%, 2021: 16.4%). In logistic regression analysis, age was found to significantly affect both anti-A and anti-B antibody titers (anti-A, adjusted odds ratio 0.36, 95% CI 0.31-0.41; anti-B, 0.42, 0.37-0.47), and BMI (0.82, 0.73-0.92) and other time-related factors (0.79, 0.71-0.88) significantly affect anti-B antibody titers. Subgroup analysis revealed decreased rate of high anti-B titers in the higher age group in 2021. CONCLUSION: The rate of high ABO antibody titers, especially high anti-B titers, was significantly decreased in 2021, and our results suggested an association with aging and obesity of blood donors as well as other time-related factors.

Anti-A and anti-B titers, age, gender, biochemical parameters, and body mass index in Japanese blood donors.

It has been reported that anti-A and anti-B (ABO antibody) titers decrease with age, but little is known about the association between ABO antibody titers and physiologic/biochemical parameters such as body mass index (BMI), gamma-glutamyl transpeptidase (GGT), and total cholesterol (T-Cho). We investigated the present situation of ABO antibody titers among healthy blood donors in Japan and the physiologic/biochemical factors that may be associated with changes in ABO antibody titers. Plasma from 7450 Japanese blood donors was tested for ABO antibody titers using ABO reverse typing reagents by an automated microplate system; donor samples were classified into low, middle, and high titers according to the agglutination results obtained with diluted plasma samples. Multivariate regression analysis was performed to analyze the association between ABO antibody titers and age, gender, biochemical parameters (alanine transaminase [ALT], GGT, globulin, T-Cho, and glycosylated albumin [GA]), and BMI according to the ABO blood groups. A significant correlation between ABO antibody titers and age/gender, except for gender in anti-A of blood group B donors, was observed. BMI showed significant but negative correlations with anti-A and anti-B (ß = -0.085 and -0.062, respectively; p < 0.01) in blood group O donors. In addition, significant but negative correlations between GGT and T-Cho with anti-B of blood group A donors (ß = -0.055 and -0.047, respectively; p < 0.05) were observed. Although differences existed among the ABO blood groups, ABO antibody titers seem to be associated with physiologic and biochemical parameters of healthy individuals.

Characteristics of ABO Antibodies in Group O Malaysian Blood Donors.

Background: Haemolytic transfusion reactions (HTRs) due to anti-A and anti-B antibodies in Group O blood products are rare but potentially fatal. This study aimed to identify the prevalence of high ABO antibody titre and the immunoglobulin (Ig) classes (IgM only or with IgG) and the prevalence of haemolysin antibodies in Group O blood donors. Methods: Plasma from Group O blood donors was tested by using antibody titration at room temperature. Titres ≥ 64 were considered high. The plasma was treated with 0.01 M dithiothreitol (DTT) to determine the presence of IgG antibodies and titre. IgG titres ≥ 64 were considered high. Tests for haemolysis were conducted by mixing the plasma with 3% fresh A1 and B cell suspensions and incubating at 37 °C. The haemolysis was observed macroscopically. Results: Of 311 donors, 238 (76.5%) showed high anti-A and/or anti-B antibody titres. The highest antibody titre obtained was 256. Female and younger donors (< 40 years old) had higher anti-A and anti-B titres. The anti-B titre showed an association with gender (P < 0.001), and was high in female donors (77.8%). Males aged over 50 years old were found to have low mean titre antibodies. Most donors had both IgM and IgG ABO antibodies. The prevalence of haemolysins in our population was 3.5%. Conclusion: Most of our O blood donors had a high ABO antibody titre but a low prevalence of haemolysins. Males aged over 50 years old are the best O donors for preventing HTRs, particularly when mismatch transfusion is required. We recommend a transfusion unit screen for ABO antibody titre in younger female donors (< 40 years old), to prevent the transfusion of high titre O blood products into non-O recipients.

Identification of Cyclic Dipeptides and a New Compound (6-(5-Hydroxy-6-methylheptyl)-5,6-dihydro-2H-pyran-2-one) Produced by Streptomyces fungicidicus against Alternaria solani.

As an important microbial resource, Actinomycetes, especially Streptomyces, have important application values in medicine and biotechnology. Streptomyces fungicidicus SYH3 was isolated from soil samples in tomato-growing areas and showed good inhibitory effects on Alternaria solani in tomato. To obtain pure active compounds, SYH3 fermentation broth was subjected to XAD-16 macroporous resin and silica gel column chromatography. Combined with the repeated preparation and separation of preparative high-performance liquid chromatography (HPLC), a total of four monomer compounds were obtained after activity tracking. Compound 4 was identified as a new six-membered lactone ring compound named 6-(5-hydroxy-6-methylheptyl)-5,6-dihydro-2H-pyran-2-one by 1D and 2D nuclear magnetic resonance (NMR) data and mass spectrometry (MS). The other three active compounds belong to the cyclodipeptide, and their half maximal inhibitory concentration (IC50) values against A. solani were 43.4, 42.9, and 30.6 µg/mL, respectively. Compound 4 significantly inhibited the spore germination and induced swollen and deformed local hyphae of A. solani with an IC50 value of 24.9 µg/mL. Compound 4 also had broad-spectrum antifungal activity and had a good antifungal effect on the tested plant-pathogenic fungi. The modes of action of new compound (4) still require further investigation, representing a novel and effective anti-fungal agent for future application.

Quantification of anti-A of IgM or IgG isotype using three different methodologies.

BACKGROUND: Reliability of ABO-antibody measurement is important in the context of supplying low-titer ABO incompatible plasma-containing blood products. This study investigated the correlation of anti-A measurements between three different titer methodologies. METHODS: Thirty-four blood group O individuals were included. IgM and IgG anti-A was measured by three different methods: (1) manual method (Bio-Rad ID-gel card), (2) automated method (Immucor NEO), (3) flow cytometry (FC) with calibration in molecules of equivalent fluorochrome (MEF). Data were log2 transformed to titer steps (TS) and log2 MEF, respectively. All three methods were benchmarked against the 14/300 WHO anti-A/anti-B standard reagent. RESULTS: The correlation between the manual and automated methods was statistically significant for both IgM (Spearman's rs  = 0.89, p < .0001) and IgG (rs  = 0.95, p < .0001). The mean TS difference between the manual and automated methods was 0.61 for IgM (p = .0033) and 2.1 for IgG (p < .0001). The manual method yielded IgM titer results that were generally 1 titer step higher than the automated method, whereas for the IgG titrations the difference was generally a median of 2 TS higher. The FC median log2 MEF level was significantly correlated with TS of IgG and IgM for both manual and automated agglutination-based titer methods (0.69 ≤ r2  ≤ 0.91). With the WHO standard reagent, the manual method produced the expected results while the automated method's results were 1 TS lower for both IgM and IgG at all dilutions tested. CONCLUSION: These results indicate that all three methods are suitable for measuring anti-A in group O whole blood.

Anti-A and SARS-CoV-2: an intriguing association.

BACKGROUND: Blood groups and anti-A isohemagglutinin may be involved in susceptibility to SARS-CoV-2 infection. MATERIALS AND METHODS: We retrospectively studied 268 COVID-19 convalescent plasma donors and 162 COVID-19 inpatients (total 430 subjects, confirmed by RT-PCR) and 2,212 healthy volunteer first-time blood donors as a control group. These were further divided into two groups: those with anti-A (blood types O and B) and those without it (types A and AB). Titres of nucleoproteins, and neutralizing SARS-CoV-2 antibody were measured in the convalescent plasma donors and inpatients. Multivariate logistic regression and non-parametric tests were applied. RESULTS: Persons having types O or B showed less infection prevalence than those of types A or AB (OR = 0·62, 95% CI 0·50-0·78; P < 0·001), but there was no difference when COVID-19 inpatients were analysed. Immunoglobulins M, G and A were lower in COVID-19 subjects of types O or B group than those of A or AB (0·16 vs. 0·19; P = 0·03, 2·11 vs. 2·55; P = 0·02, 0·23 vs. 0·32; P = 0·03, respectively). CONCLUSION: In this retrospective cohort, COVID-19 individuals were less likely to belong to blood types O and B, and also had lower SARS-CoV-2 antibody titres than A and AB individuals. COVID-19 severity did not associate with the blood groups.

Feasibility of Immunoadsorption plasmapheresis in an infant for ABO-incompatible solid organ transplant-A reality.

BACKGROUND: Immunoadsorption (IA) plasmapheresis is standard modality for pretransplant desensitization in ABO-incompatible solid organ transplants though technically challenging when considered for an infant or a child less than 10 kg due to non-availability of pediatric immunoadsorption (IA) columns. The major challenge is to maintain hemodynamic stability considering the large extracorporeal circuit volume meant for adults. To our best knowledge after extensive search in acclaimed global medical journals, this is the first successful attempt in an underweight (6 kg) infant of less than 1 year of age using adult size IA Column thus making it a reality. CASE CHARACTERISTICS: We report an 8-month-old male infant (A positive) of 6 kg with decompensated liver disease secondary to extrahepatic biliary atresia requiring urgent live donor liver transplantation with AB positive donor with significantly elevated pretransplant anti-B IgG/ IgM antibody titers >1:1024. Baby underwent multiple sessions of anti-B immunoadsorption plasmapheresis to lower anti-B IgM / IgG titers using available adult anti-B immunoadsorption column. Postprocedure, the antibody titers reduced to 1:8 (anti-IgG) 1:16 (anti-IgM) followed by successful ABO-incompatible live donor liver transplant (LDLT). OUTCOME: Anti-B titers remained in normal range in the immediate and post-transplant period with satisfactory liver functions and no rejection. CONCLUSION: Immunoadsorption plasmapheresis for ABO-incompatible solid organ transplantation in infants gives desirable results and can be offered to small sized infants using currently available adult sized IA columns when conducted with adequate technical expertise.

Complement activating ABO anti-A IgM/IgG act synergistically to cause erythrophagocytosis: implications among minor ABO incompatible transfusions.

BACKGROUND: Typically minor ABO incompatible platelet products are transfused without any incident, yet serious hemolytic transfusion reactions occur. To mitigate these events, ABO 'low titer' products are used for minor ABO incompatible transfusions. We sought to understand the role of IgM/IgG and complement activation by anti-A on extravascular hemolysis. METHODS: Samples evaluated included (i) Group O plasma from a blood donor whose apheresis platelet product resulted in an extravascular transfusion reaction, (ii) Group O plasma from 12 healthy donors with matching titers that activated complement (N = 6) or not (N = 6), and (iii) Group O sera from 10 patients with anti-A hemolysin activity. A flow cytometric monocyte erythrophagocytosis assay was developed using monocytes isolated by immunomagnetic CD14-positive selection from ACD whole blood of healthy donors. Monocytes were frozen at - 80 °C in 10% dimethyl sulfoxide/FBS and then thawed/reconstituted on the day of use. Monocytes were co-incubated with anti-A-sensitized fluorescently-labeled Group A1 + RBCs with and without fresh Group A serum as a source of complement C3, and erythrophagocytosis was analyzed by flow cytometry. The dependency of IgM/IgG anti-A and complement C3 activation for RBC erythrophagocytosis was studied. Anti-A IgG subclass specificities were examined for specific samples. RESULTS: The plasma and sera had variable direct agglutinating (IgM) and indirect (IgG) titers. None of 12 selected samples showed monocyte-dependent erythrophagocytosis with or without complement activation. The donor sample causing a hemolytic transfusion reaction and 2 of the 10 patient sera with hemolysin activity showed significant erythrophagocytosis (> 10%) only when complement C3 was activated. The single donor plasma and two sera demonstrating significant erythrophagocytosis had high IgM (≥ 128) and IgG titers (> 1024). The donor plasma anti-A was IgG1, while the patient sera were an IgG3 and an IgG1 plus IgG2. CONCLUSION: High anti-A IgM/IgG titers act synergistically to cause significant monocyte erythrophagocytosis by activating complement C3, thus engaging both Fcγ- and CR1-receptors.

Retrospective analysis of HDFN due to ABO incompatibility in a single institution over 6 years.

OBJECTIVES: To study the rate of ABO haemolytic anaemia of fetus and newborn (HDFN) in one institution over 6 years. BACKGROUND: ABO major incompatibility between mothers and their newborns occurs in about 10% of births. So, mothers with an O blood group may form IgG-class antibodies against A and B antigens, which could pass across the placenta and lead to a variable degree of HDFN in the newborn. METHODS: At our institution, we have reviewed data regarding ABO-based HDFN in the last 6 years. RESULTS: We found that, in 28 089 deliveries, an ABO major incompatibility between mothers and newborns occurs in 11% of cases, with 72% of O/A and 28% of O/B incompatibility. In turn, 23% of these newborns had an eluate-confirmed positive direct antiglobulin test [DAT; 74% (511) were due to anti-A and 26% (179) to anti-B], with 1·0% requiring invasive treatments (exchange transfusion or intravenous immunoglobulin). Overall, 2·5% of the total newborns had a positive DAT for an anti-A or anti-B antibody, and 0·11% required invasive treatment in addition to phototherapy for their HDFN. CONCLUSIONS: Serological ABO HDFN is a relatively frequent event when an O-A/O-B incompatibility between mothers and their newborn occurs and, in most cases, translates into a self-limiting disease, with a small number of newborns requiring invasive treatments. The DAT test, although not predictive of disease severity, appears to be a useful tool to monitor babies born from O-A/O-B-incompatible pregnancies and to identify those who may require treatment.

Modeling-based optimization approaches for the development of Anti-Agrobacterium tumefaciens activity using Streptomyces sp TN71.

A new aerobic bacterium TN71 was isolated from Tunisian Saharan soil and has been selected for its antimicrobial activity against phytopathogenic bacteria. Based on cellular morphology, physiological characterization and phylogenetic analysis, this isolate has been assigned as Streptomyces sp. TN71 strain. In an attempt to increase its anti-Agrobacterium tumefaciens activity, GYM + S (glucose, yeast extract, malt extract and starch) medium was selected out of five different production media and the medium composition was optimized. Plackett-Burman design (PBD) was used to select starch, malt extract and glucose as parameters having significant effects on antibacterial activity and a Box-Behnken design was applied for further optimization. The analysis revealed that the optimum concentrations for anti-A. tumefaciens activity of the tested variables were 19.49 g/L for starch, 5.06 g/L for malt extract and 2.07 g/L for glucose. Several Artificial Neural Networks (ANN): the Multilayer perceptron (MLP) and the Radial basis function (RBF) were also constructed to predict anti-A. tumefaciens activity. The comparison between experimental with predicted outputs from ANN and Response Surface Methodology (RSM) were studied. ANN model presents an improvement of 12.36% in terms of determination coefficients of anti A. tumefaciens activity. To our knowledge, this is the first work reporting the statistical versus artificial intelligence based modeling for optimization of bioactive molecules against phytopathogens.

The lignicolous fungus Trametes versicolor (L.) Lloyd (1920): a promising natural source of antiradical and AChE inhibitory agents.

This study aimed to determine antiradical (DPPH• and •OH) and acetylcholinesterase (AChE) inhibitory activities along with chemical composition of autochtonous fungal species Trametes versicolor (Serbia). A total of 38 phenolic compounds with notable presence of phenolic acids were identified using HPLC/MS-MS. Its water extract exhibited the highest antiradical activity against •OH (3.21 µg/mL), among the rest due to the presence of gallic, p-coumaric and caffeic acids. At the concentration of 100 µg/mL, the same extract displayed a profound AChE inhibitory activity (60.53%) in liquid, compared to donepezil (89.05%), a drug in clinical practice used as positive control. The flavonoids baicalein and quercetin may be responsible compounds for the AChE inhibitory activity observed. These findings have demonstrated considerable potential of T. versicolor water extract as a natural source of antioxidant(s) and/or AChE inhibitor(s) to be eventually used as drug-like compounds or food supplements in the treatment of Alzheimer's disease.

Transplantation of ABO A2 kidneys into O recipients: do IgM anti-A1 titers matter?

BACKGROUND: The ABO blood subgroup A2 expresses lower levels of A antigen on the cell surface and is less immunogenic toward anti-A immunoglobulin present in blood type O or B recipients. Previous studies have shown successful kidney transplantation from A2 donors into O or B recipients with low pre-transplant anti-A titers. Previous studies suggest good results with recipient IgG titers <1:8. Few studies have specifically evaluated the importance of anti-A1 IgM titers on early outcomes following A2 to O or B kidney transplantation. METHODS: We performed a single center, retrospective review of all A2 to O living donor kidney transplants. All recipients had pre-transplant anti-A IgG titers <1:8. IgM titers were measured in all recipients and were reported but not used to determine eligibility for transplant. RESULTS: From 2001 to 2013, we performed seven consecutive A2 to O living donor kidney transplants. Early allograft dysfunction, acute rejection or thrombotic microangiopathy, occurred in four patients and were associated with high IgM titers despite low IgG titers. CONCLUSIONS: Our data show a high incidence of early acute rejection or thrombotic microangiopathy in A2 to O kidney transplants with high recipient anti-A IgM titers despite low IgG titers. Steps to lower anti-IgM pre-transplant may reduce the risk of early allograft dysfunction in A2 to O or B kidney transplants. Attention should be paid to IgM titers in establishing individual center selection criteria for A2 to B kidney transplants under the new UNOS kidney allocation system.

High resolution respirometry analysis of polyethylenimine-mediated mitochondrial energy crisis and cellular stress: Mitochondrial proton leak and inhibition of the electron transport system.

Polyethylenimines (PEIs) are highly efficient non-viral transfectants, but can induce cell death through poorly understood necrotic and apoptotic processes as well as autophagy. Through high resolution respirometry studies in H1299 cells we demonstrate that the 25kDa branched polyethylenimine (25k-PEI-B), in a concentration and time-dependent manner, facilitates mitochondrial proton leak and inhibits the electron transport system. These events were associated with gradual reduction of the mitochondrial membrane potential and mitochondrial ATP synthesis. The intracellular ATP levels further declined as a consequence of PEI-mediated plasma membrane damage and subsequent ATP leakage to the extracellular medium. Studies with freshly isolated mouse liver mitochondria corroborated with bioenergetic findings and demonstrated parallel polycation concentration- and time-dependent changes in state 2 and state 4o oxygen flux as well as lowered ADP phosphorylation (state 3) and mitochondrial ATP synthesis. Polycation-mediated reduction of electron transport system activity was further demonstrated in 'broken mitochondria' (freeze-thawed mitochondrial preparations). Moreover, by using both high-resolution respirometry and spectrophotometry analysis of cytochrome c oxidase activity we were able to identify complex IV (cytochrome c oxidase) as a likely specific site of PEI mediated inhibition within the electron transport system. Unraveling the mechanisms of PEI-mediated mitochondrial energy crisis is central for combinatorial design of safer polymeric non-viral gene delivery systems.

A rare case report of chronic variable immunodeficiency divulged by ABO discrepancy.

ABO discrepancy refers to incongruence between the results of red cell and serum groupings. One such case is described here; the discrepant results of whose routine ABO grouping led to the diagnosis of common variable immunodeficiency. There was no reaction in the reverse grouping of a young patient presenting with recurrent bacterial infections, pointing towards an absence of antibodies in the serum. Diagnosis was made on the basis of markedly decreased serum immunoglobulin levels and by serum protein electrophoresis showing scanty gamma regions.

Anti-A and anti-B haemagglutinin levels in intravenous immunoglobulins: are they on the rise? A comparison of four different analysis methods and six products.

Recent reports of severe haemolytic reactions upon high dose treatment with new generation intravenous immunoglobulins (IVIGs) prompted us to examine the anti-A and anti-B haemagglutinin content of these therapeutics. We compared four different test methods, namely the indirect and direct haemagglutination test as described in the European Pharmacopoiea (Ph. Eur.) and two commercial gelcard systems with the aim to define the most reliable method for a large-scale comparison of different IVIG products. Absolute titres varied when the same samples were analyzed by the four methods, while the relative ranking of six different IVIG preparations representing different manufacturing classes was identical. New generation IVIGs showed 1-2 titre steps higher anti-A titres than the older products. Haemagglutinin titres of all 48 IVIG batches analyzed were within the current Ph. Eur. specification of ≤1:64 when tested by the official pharmacopoeial method. Based on efficiency, reliability and lower costs, the direct gelcard method could be a valid alternative to the official Ph. Eur. method to serve as a limit test. However, due to the highest intermediate precision, the official Ph. Eur. method seems to be most suitable to compare haemagglutinin titres of different IVIG products.

Severe Hemolytic Disease of a Newborn with Bilirubin of 37.3 mg/dL and High anti-A Titer: Corrected with Reconstituted Whole Blood Exchange.

High neonatal bilirubin is a common phenomenon responding to phototherapy. We report a case of a newborn with a highly elevated bilirubin of 37.3 mg/dL due to ABO incompatibility between the mother (Group O) and the newborn (Group A) requiring whole blood exchange, a procedure performed rarely to treat newborn hyperbilirubinemia. The newborn (38.8 weeks of gestation) initially showed a total bilirubin of 8.4 mg/dL and was discharged after being stabilized by phototherapy. However, the baby returned to the hospital with highly elevated bilirubin and was admitted to the Neonatal Intensive Care Unit (NICU). Emergent reconstituted whole blood exchanger therapy was initiated due to refractoriness to phototherapy and IVIG. Markedly elevated anti-A titer was found in the mother's blood (1:512) and cord blood (1:128). The baby was stabilized and eventually discharged with a serum bilirubin of 13.8 mg/dL. This case demonstrates the possible predictive value of mother/cord blood anti-A titers in severe newborn hyperbilirubinemia, which may prevent premature discharge and trigger early initiation of lifesaving therapy.

Anti-A and anti-B titers in A, B and O whole blood donors: Beyond "dangerous O".

BACKGROUND AND OBJECTIVES: Hemolytic transfusion reactions (HTRs) pose significant risks in transfused patients, with anti-A and anti-B antibodies in donor plasma being potential contributing factors. Despite advancements in component preparation, HTRs remain a concern, particularly with apheresis-derived platelets. This study aimed to determine the prevalence of high anti-A and anti-B titers among A, B, and O blood group donors and to explore factors associated with high titers. MATERIALS AND METHODS: A cross-sectional observational study was conducted over 18 months, enrolling 978 participants from a tertiary care teaching hospital in Western India. Anti-A and anti-B titers were determined using the Conventional Tube Technique (CTT). Statistical analysis assessed correlations between high titers and demographic factors. RESULTS: The majority of participants were young males (98.8%). Prevalence of high titers for IgM anti-A was 12.2% and IgG anti-A was 2.5%. For anti-B, IgM titers were 2.3% and IgG titers were 0.2%. The prevalence of dangerous O was found to be 14.1%, while 3.52% and 10.5% of A and B blood group donors were found to have high titers, respectively. Factors associated with high titers included female gender, vegetarian diet, age <30 years, and O blood group. CONCLUSION: The study sheds additional light and provides supplementary information regarding the prevalence and correlation of high anti-A and anti-B titers among O, A and B blood donors. Understanding these factors is crucial for optimizing transfusion safety protocols, including selective screening of platelet units and tailored transfusion strategies based on donor characteristics.

Prevention of Blood Incompatibility Related Hemagglutination: Blocking of Antigen A on Red Blood Cells Using In Silico Designed Recombinant Anti-A scFv.

Critical blood shortages plague healthcare systems, particularly in lower-income and middle-income countries. This affects patients requiring regular transfusions and creates challenges during emergencies where universal blood is vital. To address these shortages and support blood banks during emergencies, this study reports a method for increasing the compatibility of blood group A red blood cells (RBCs) by blocking surface antigen-A using anti-A single chain fragment variable (scFv). To enhance stability, the scFv was first modified with the addition of interdomain disulfide bonds. The most effective location for this modification was found to be H44-L232 of mutant-1a scFv. ScFv was then produced from E.coli BL21(DE3) and purified using a three-step process. Purified scFvs were then used to block maximum number of antigens-A on RBCs, and it was found that only monomers were functional, while dimers formed through incorrect domain-swapping were non-functional. These antigen-blocked RBCs displayed no clumping in hemagglutination testing with incompatible blood plasma. The dissociation constant KD was found to be 0.724 µM. Antigen-blocked RBCs have the potential to be given to other blood groups during emergencies. This innovative approach could significantly increase the pool of usable blood, potentially saving countless lives.

Rapid and label-free A2 peptide epitope decorated CoFe2O4-C60 nanocomposite-based electrochemical immunosensor for detecting Visceral Leishmaniasis.

Diagnosis of Visceral Leishmaniasis is challenging due to the shared clinical features with malaria, typhoid, and tuberculosis. A CoFe2O4-C60 nanocomposite-based immunosensor decorated with a sensitive A2 peptide antigen was fabricated to detect anti-A2 antibodies for application in visceral leishmaniasis diagnosis. The flame-synthesised nanocomposite was characterised using Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX), Raman spectroscopy and electrochemical impedance spectroscopy (EIS) techniques. N terminated specific A2 peptide epitope antigen (NH2-QSVGPLSVGP-OH) was synthesised and characterised by high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectroscopy (LC-MS). Using EDC/NHS, A2 peptide antigen (Apg) was immobilised on the CoFe2O4-C60-modified electrode. The performance of the immunosensor, Apg-CoFe2O4-C60NP/GCE, was evaluated by testing its ability to detect varying concentrations of anti-A2 antibody solution in PBS and spiked serum with 1 mM [Fe(CN)6]3-/4- in 0.01 M PBS (pH 7.4) as supporting electrolyte. using differential pulse voltammetry. The immunosensor showed excellent reproducibility and a linear range of 10-10-10-1 µg/mL, with an experimental detection limit of 30.34 fg/mL. These results suggest that the fabricated sensor has great potential as a tool for diagnosing visceral leishmaniasis.