ABO Antibody Titers Research Articles

Long-term isoagglutinin monitoring after ABO-incompatible kidney transplantation.

This study aimed to evaluate whether a 2-week period of daily isoagglutinin titer testing after ABO-incompatible kidney transplantation (ABOi-KT) is sufficient to ensure successful engraftment and to advocate for an extension of the monitoring duration in specific situations. We reviewed patients from January 2022 to December 2023 at Asan Medical Center who underwent therapeutic plasma exchange (TPE) due to elevated ABO antibody titers and suspected acute antibody-mediated rejection (AMR) after ABOi-KT. Data collected included pre- and posttransplantation laboratory results, clinical and procedural information, imaging studies, and needle biopsy results of the renal graft. We encountered 3 cases of acute AMR 2 weeks after transplantation. All cases exhibited simultaneous increases in anti-ABO antibody isoagglutinin titers, creatinine, and C-reactive protein levels. Clinical signs, including fever, suggested possible infection, and renal graft biopsy, confirmed AMR in all cases. Two cases underwent graftectomy, while the third recovered renal function after conservative treatment, including TPE. Our findings suggest that a 2-week monitoring period for isoagglutinin titers after ABOi-KT may not be sufficient to detect late AMR. Extending the monitoring duration and considering lifelong fresh-frozen plasma transfusion with graft-compatible blood types, along with periodic isoagglutinin titer testing in cases of suspected AMR, may improve long-term graft outcomes.

In-vitro Dilution of Human Plasma to Reduce ABO Antibody Titer Levels While Preserving Coagulation Factors

In-vitro Dilution of Human Plasma to Reduce ABO Antibody Titer Levels While Preserving Coagulation Factors

Estimation of ABO Anti-A and Anti-B Agglutinin Titers among Blood Donors at a Tertiary Care Referral Teaching Hospital Blood Centre in Southern India: A Cross-sectional Study

Introduction: Transfusion of blood Group O and its components with high ABO antibody titers to non O recipients has been shown to cause acute transfusion reactions, especially in platelet transfusions, as platelets contain significant amounts of ABO antigen on their surface as well as Anti-ABO alloisogglutinins in plasma. Aim: To estimate the ABO Anti-A and Anti-B agglutinin titers among blood donors at a tertiary care referral teaching hospital blood centre. Materials and Methods: This cross-sectional observational study was conducted at the Immunohaematology laboratory of the Department of Transfusion Medicine, Sri Venkateswara Institute of Medical Sciences, Tirupati, Andhra Pradesh, India, from March 2021 to June 2022. All blood donors presenting to the blood centre were screened for eligibility for blood donation. Donors who fulfilled the eligibility criteria as per the Drugs and Cosmetics Act, 1940, and Rules, 1945 were included. Anti-A and Anti-B titers were determined by the conventional tube method with dilutions of 1 in 2, 1 in 4, 1 in 8, 1 in 16, 1 in 32, 1 in 64, 1 in 128, 1 in 256, 1 in 512, and 1 in 1024. A titer of <64 was considered as a low titer, while a titer of >64 was considered as a high titer. Results: A total of 399 donors were included in the study, with 393 (98.5%) being males and 6 (1.5%) being females. The mean age of the study population was 28.49 years. Among blood group A, the percentage of individuals with an IgM anti-B titer of <64 was 85.44% (88) and >64 was 14.56% (15), whereas in blood group B, IgM anti-A titers of <64 were 65.5% (93) and >64 were 34.5% (49). In blood group O, the percentage of individuals with <64 and >64 titers of IgM anti-A were 52.60% (81) and 47.40% (73), respectively, whereas for anti-B, <64 and >64 titers were 77.92% (120) and 22.08% (34), respectively. Conclusion: It is recommended that a database be maintained in all institutes by estimating antibody titers for every A, B, O blood group donors. Whole blood or platelets from group O donors with IgM Anti-A and Anti-B antibody titers <64 can only be transfused across the ABO barrier. As the majority of group A donors had titers <64, group A platelets may be transfused across the ABO barrier in emergency situations.

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 (β = -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 (β = -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.

Pretransplant immunologic risk assessment in high baseline ABO antibody titers and donor-specific anti-human leukocyte antigen antibodies in ABO incompatible kidney transplantation

Pretransplant immunologic risk assessment in high baseline ABO antibody titers and donor-specific anti-human leukocyte antigen antibodies in ABO incompatible kidney transplantation

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

Background and ObjectivesPreviously (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 MethodsSerum/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. ResultsCompared 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. ConclusionThe 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.

Platelet Additive Solutions as an Alternative Storage Medium of Apheresis Platelets to Reduce ABO Antibody Titer for ABO-Incompatibility Platelet Transfusion.

Introduction Platelet additive solutions (PASs) are nutrient media commonly used to replace and reduce the need for storage plasma. They are an alternative medium to maintain high-quality platelets lasting longer on the shelf for about seven days. Platelets with high titer of ABO antibody can pose a hemolytic transfusion reaction (HTR) risk if units are given across the ABO barrier. The risk of complication is greater when group O platelet is released to non-group O patients. The PAS has been known as a safe medium, where the titer of ABO antibodies is expected to be diluted. In this study, we compared the anti-A and anti-B antibody titers of apheresis platelets in PAS and non-PAS (plasma) as the suspending media. Methods A total of 20apheresis platelet donors were selected, with seven from blood group A, eight from blood group B, and five from blood group O. The platelets were collectedusing an Amicus cell separator. They were suspended in PAS and plasma before being stored at a temperature range of 22-24ºC. Anti-A (blood group B and O)and Anti-B(blood group A and O) antibody titers were measured and compared between the two suspending media. Wilcoxon signed-rank test is used for statistical analysis, and a p-value <0.05 is considered significant. Results The median titer of the anti-A antibody of apheresis platelets showed a significant difference between suspended in PAS (2.50) and plasma (4.00), p=0.002. Similar findings were also seen with the median titer of the anti-B antibody of apheresis platelet, in which it showed a significant difference between suspended in PAS (2.00) and plasma (4.00), p=0.004. It was observed that there was a significant reduction in both anti-A and anti-B antibody titers in the PAS as compared to the plasma group. Conclusion The decrease in ABO antibody titer in apheresis platelets stored with PAS can be beneficial for patients. This reduces the risk of HTRs if ABO-incompatible platelet units need to be issued. Thus, using PAS as a storage medium significantly improves platelet inventory management without compromising patient safety.

A prospective observational study to evaluate effect of heat inactivation on ABO titers performed by column agglutination technology and conventional tube technique.

When determining ABO antibody titers, immunoglobulin G (IgG) antibodies can be masked by immunoglobulin M (IgM) antibodies. Hence, the measurement of actual concentration of IgG requires methods like heat inactivation (HI) of plasma. This study was aimed at determining the effects of HI on IgM and IgG titers performed by conventional tube technique (CTT) and column agglutination technique (CAT). This was a prospective, observational study conducted from October 2019 to March 2020. All consecutive A, B, and O group donors who gave consent for participation were included. All samples were consecutively tested by CTT and CAT, before and after HI (pCTT, pCAT). A total of 300 donors were included. IgG titers were found to be more than IgM titers. For group O, IgG titer results were higher for both anti-A and anti-B compared to group A and B. For group A, B, and O, pretreatment results were higher than posttreatment IgG titer results. Median anti-A titers were similar to median anti-B titers across all categories. Median IgM and IgG titers were higher for group O individuals than nongroup O individuals. There was reduction in IgG and IgM titers after HI of plasma. One log reduction in median titers was observed when ABO titers were performed by CAT and CTT. There is one log difference between median antibody titers estimated using heat inactivated and nonheat inactivated plasma. The use of HI for ABO isoagglutinin titer estimation can be considered in low resource settings.

Progress in perioperative management of ABO-incompatible pediatric liver transplantation

ABO incompatible(ABO-I) liver grafts will affect the prognosis of liver transplantation. With the improvement of perioperative treatment,including plasma exchange,rituximab,splenectomy,etc.,the prognosis of ABO-I liver transplantation has been greatly improved. Because children's immune systems are not fully developed,the perioperative management of ABO-I pediatric liver transplantation is significantly different from that of adults. Reducing the perioperative anti-donor ABO antibody titer is the key to the perioperative management of ABO-I liver transplantation. This article summarizes literatures on the perioperative management of ABO-I pediatric liver transplantation, including the perioperative anti-rejection regimen in pediatric recipients of different ages, splenectomy, postoperative monitoring and postoperative complications, etc.

A prospective observational study to compare abo isoagglutinin titer by conventional test tube and column agglutination technique after heat inactivation of plasma in O blood group individuals

Background and Aims: When determining ABO antibody titers, IgG antibodies can be masked by immunoglobulin M (IgM) antibodies. Hence, the measurement of actual concentration of IgG requires methods such as heat inactivation (HI) of plasma. This study was aimed at determining the effects of HI on IgM and IgG titers performed by conventional test tube (CTT) technique and column agglutination technique (CAT). Materials and Methods: This was a prospective, observational study conducted from October 2018 to March 2020. All consecutive O group donors who gave consent for participation were included in the study. All samples were consecutively tested by CTT and CAT, before and after HI (pCTT and pCAT). Results: A total of 2005 donors were included. IgG titers were found to be more than IgM titers. pCTT IgG results are similar or lower when compared to results obtained by solid-phase red cell adherence (SPRCA), whereas pCAT IgG titers were higher with pCAT when compared to hemagglutination (HA)/SPRCA. The results of titers obtained by pCTT were lower as compared to pCAT and HA/SPRCA, with majority giving results <64. The median IgG and IgM titers for both anti-A and anti-B were highest in pCAT, whereas the median IgG and IgM anti-A and anti-B titers were similar to HA and pCTT. Conclusion: Results obtained by HA/SPRCA were closer to results obtained by pCTT, with the advantage of less time consumption, automation requiring less expertise, and no interobserver variation. Titers obtained by pCAT were higher in comparison to HA/SPRCA and pCTT results, due to high sensitivity.

Transplant outcomes of 100 cases of living-donor ABO-incompatible kidney transplantation.

Although ABO-incompatible (ABOi) kidney transplantation (KT) has been performed successfully, a standard preconditioning regimen has not been established. Based on the initial antidonor ABO antibody titers, an individualized preconditioning regimen is developed, and this study explored the efficacy and safety of the regimen. From September 1, 2014, to September 1, 2020, we performed 1668 consecutive living-donor KTs, including 100 ABOi and 1568 ABO-compatible (ABOc) KTs. ABOi KT recipients (KTRs) with a lower antibody titer (≤1:8) were administered oral immunosuppressive drugs (OIs) before KT, while patients with a medium titer (1:16) received OIs plus antibody-removal therapy (plasma exchange/double-filtration plasmapheresis), patients with a higher titer (≥1:32) were in addition received rituximab (Rit). Competing risk analyses were conducted to estimate the cumulative incidence of infection, acute rejection (AR), graft loss, and patient death. After propensity score analyses, 100 ABOi KTRs and 200 matched ABOc KTRs were selected. There were no significant differences in graft and patient survival between the ABOi and ABOc groups (P = 0.787, P = 0.386, respectively). After using the individualized preconditioning regimen, ABOi KTRs showed a similar cumulative incidence of AR (10.0% υs . 10.5%, P = 0.346). Among the ABOi KTRs, the Rit-free group had a similar cumulative incidence of AR ( P = 0.714) compared to that of the Rit-treated group. Multivariate competing risk analyses revealed that a Rit-free regimen reduced the risk of infection (HR: 0.31; 95% CI: 0.12-0.78, P = 0.013). Notably, antibody titer rebound was more common in ABOi KTRs receiving a Rit-free preconditioning regimen ( P = 0.013) than those receiving Rit. ABOi KTRs with antibody titer rebound had a 2.72-fold risk of AR (HR: 2.72, 95% CI: 1.01-7.31, P = 0.048). ABOi KTRs had similar serum creatinine and estimated glomerular filtration rate compared to those of ABOc KTRs after the first year. An individualized preconditioning regimen can achieve comparable graft and patient survival rates in ABOi KT with ABOc KT. Rit-free preconditioning effectively prevented AR without increasing the risk of infectious events in those with lower initial titers; however, antibody titer rebound should be monitored.

The effect of probiotic use on ABO antibody titers.

The use of probiotics brings numerous benefits to the immune system, including an increase in antibody production. The development of ABO antibodies may occur naturally due to the bacteria of the intestinal microbiota. However, high titers of ABO antibodies can lead to hemolytic disease of the fetus and newborn and can cause immune transfusion reactions. In this context, this study aimed to evaluate the effect of probiotic consumption on ABO antibody titers in humans. ABO blood group, ABO antibody titer, and fecal pH and Bifidobacteria concentration were determined for 126 healthy individuals before and after daily consumption of yogurt containing Lactobacillus acidophilus and Bifidobacterium lactis over a 1-month period. No changes in fecal pH were observed after probiotic consumption, regardless of ABO blood group. There was, however, an increase in the fecal concentration of Bifidobacteria in individuals with blood group A but not for those with group B or O. A decrease in the titer of anti-B was observed, despite the increase in the concentration of Bifidobacteria in feces being unrelated to fecal pH, in blood group A individuals. Our study, therefore, sought to understand the relationship between probiotics and the antibody titer of the ABO blood system. Despite our findings, further human studies are needed with other probiotic strains and molecular analyses of the intestinal microbiota.

Effect of serial plasma exchange sessions with albumin replacement on ABO antibody titers

Background Donor shortage in kidney transplantation stimulates trails of live-related transplants across the ABO antibody barrier. Successful desensitization was achieved by repeated plasmapheresis with intensified immunosuppression. This study estimates the effect of serial sessions of plasma exchange on different blood group antibody titers. Patients and methods This is a pilot study that included 25 prescribed plasma exchange treatments with albumin replacement for miscellaneous indications. Patients using plasma as a replacement during sessions, positive direct and indirect antiglobulin test and AB blood group were excluded. Blood group antibody titers were measured by the gel card method before starting plasma exchange and after each session for five sessions. Results The study included a total of 25 patients, 12 (48%) had A1 blood group, eight (32%) had blood group B, and five (20%) had blood group O. The baseline anti-(A) and anti-(B) antibody titers before plasma exchange were median (interquartile range) 128.00 (192) and 64 (64) with significant reduction after five sessions with median (interquartile range) 1 (4) and 2 (1), respectively, with P value less than 0.001. Anti-(A) and anti-(B) antibody titer percent reduction from baseline to fifth session were mean±SD=99.04 ± 0.72 and =97.93 ± 0.99%, respectively. Anti-(A) and anti-(B) antibody titers were negatively correlated with patient's age (r=0.731, P=0.005; r=0.793, P&lt;0.001, respectively). Patients with age less than 50 (n=13) years have higher anti-(A) and anti-(B) antibodies compared with patients with age more than 50 years (N=12) with P value less than 0.001. Also, on comparing patients on immunosuppressive drugs with patients not on immunosuppressive drugs as regards baseline antibody titers before exchange sessions and after five plasma exchange sessions, there was no significant difference in anti-(B) while anti-(A) titer was higher in patients without immunosuppressive drugs with P valueless than 0.05 and on fifth session, P value of 0.01. Conclusion Serial plasma exchange sessions with albumin replacement is an effective method for ABO antibody titer reduction. Baseline titers seem to be affected by age and adjuvant immunosuppressive therapy.

Determination of ABO antibody titre and haemolysin test of group O whole blood used for exchanged transfusion in a teaching hospital

Background: Group O blood donor is more readily available and is frequently used as a universal red cell donor and emergency O whole blood (EM O) for exchange transfusion in neonates. Sera from group O donors contains two separable haemolysin antibodies, anti-A and anti-B, and a cross-reacting antibody called anti-A, B (mostly IgG). The presence of haemolysins in the donors may lead to haemolysis in the recipients. Objectives: This study aims to determine the prevalence of anti-A and anti B haemolysins and titer among group O donors that we screened for emergency group O (EM O) whole blood Methodology: A cross sectional study was done to determine the prevalence of anti-A and anti B haemolysin and titer among group O blood donors screened for EM O whole blood for exchange transfusion in neonates at a teaching hospital from January to December 2018. Samples of 350 voluntary group O regular donors were selected for ABO antibodies titration and haemolysin test using the conventional tube technique at room temperature. Donors were screened for titer of 1:50 and 1:100 only. ABO antibody titer of ≥1:100 was considered as a high titer and not suitable for exchange transfusion. Titer of ≤1:50 were labeled as EM O whole blood and will be suitable for exchange transfusion. Results: A total of 350 group O blood donors were screened for the anti A and anti B haemolysin and titer. The majority of blood group O donors were male (n=215, 61%) and were age from 18-30 years old (51%). Malay was the predominant group (83%). About 52.9% of the donors were low titer (≤1:50), and 47.1% were high titer (≥1:100). Low titer was seen predominantly among male donors (61.8%). The prevalence of haemolysins in group O donors was 5.4% (n=19). Anti A and anti B haemolysins were seen in 0.57% and 2.28% of the donors, respectively, while donors having both A and B haemolysins in their sera was 2.57%. Conclusion: Prevalence of anti-A and anti-B haemolysins were low among group O blood donors. However, a significant percentage of group O donors have high titer of anti-A or anti-B. Therefore, despite the labour intensiveness of haemolysis titration technique and the frequent transfusion of group O blood for exchange transfusion, there is the need to routinely screen our donors for haemolysins in order to identify those posing the greatest risk to recipients. Bangladesh Journal of Medical Science Vol. 21 No. 02 April’22 Page : 368-372

Acute Anti-A/B Antibody-Mediated Rejection After ABO-Incompatible Kidney Transplantation Treated With Bortezomib and Plasmapheresis: A Case Report

ABO-incompatible kidney transplantation (KTP) is effective for avoiding transplantation-related issues. It is a viable alternative to ABO-compatible KTP, as both techniques have similar patient and graft survival rates. However, anti-A/B antibody-mediated rejection (AMR) can occur, resulting in poor long-term graft survival. A 45-year-old man with end-stage renal disease presented with a serum creatinine level of 10.2 mg/dL. We decided to perform KTP with spousal donation. He had panel-reactive antibody class I and II and cross matching test negativity, a 3/6 mismatch on human leukocyte antigen typing, an ABO antibody titer of 1:256, and no donor-specific antibodies. The patient and donor blood types were O+ and A+, respectively. The anti-A/B antibody titer was reduced preoperatively with rituximab (200 mg/body), plasmapheresis, and intravenous immunoglobulin (0.2 mg/kg). Basiliximab and methylprednisolone were used for induction immunosuppression, and tacrolimus, mycophenolate mofetil, and prednisolone were used for maintenance immunosuppression. KTP was successful, and graft function was initially normal. On postoperative day (POD) 5, the serum creatinine level and anti-A/B antibody titer increased from 0.9 mg/dL to 1.9 mg/dL and 1:16 to 1:64, respectively. Graft biopsy revealed acute AMR and tubular injury. We started steroid pulse therapy, plasmapheresis, and subcutaneous bortezomib (2.6 mg, twice a day, every 3 days) with no side effects. The serum creatinine level decreased from 5.7 mg/dL to 1.5 mg/dL on POD 28. Graft biopsy showed no rejection, and normal function was maintained for 40 months. Acute, early anti-A/B AMR was successfully treated with plasmapheresis and bortezomib.

ABO antibody titer performance characteristics and correlates between two automated platforms

BackgroundAABB standards require a policy for assessing transfusing ABO-incompatible plasma. After a fatal hemolytic event with incompatible plasma, our institution instituted platelet donor population titer method for ABO antibodies on the PK7300, with high-titer being defined as having isohemagglutinin titers greater than 256. We recently switched titering platforms to the Neo Iris and we seek to determine the equivalent isohemagglutinin high-titer cutoff on the Neo Iris as compared to the PK7300. MethodsWe measured the titers on 299 apheresis platelet donors and compared its performance characteristics at various cutoffs to the PK7300 reference standard. Discrepant results were manually diluted and retested on the Neo Galileo. Furthermore, since the Neo Iris is able to determine isotype and antigen specific titers, we also characterized these features in our donor population. ResultsIgM titer of 128 on the Neo Iris has better accuracy compared to the titer of 64 (94 % vs 93.6 %). Eleven of sixteen discordant results were in agreement with Neo Iris. Blood group O had the highest IgG antibody titers for both anti-A and anti-B (p = 8.4E-17 and 4.3E-09, respectively). Additionally, group O donors exhibited lower anti-A2 than anti-A1 IgG titers. DiscussionThe Neo Iris titer cut-off of 128 had the best overall accuracy and correlation with a 256 cut-off on our laboratory developed test on the PK7300 platform. Additionally, we found that group O donors had the highest titer antibodies, with typically higher IgG titers than IgM, and generally multiple dilution levels greater than other blood types.

Evaluation of Erythrocytes Magnetized Technology for Measurement of ABO Isoagglutinin Titers.

Background A variation in the measurement of ABO antibody titer has been seen among different laboratories due to lack of standardization. In our study, we aim to evaluate automated ABO isoagglutinin titer measurements by erythrocytes magnetized technology (EMT) and compare with conventional tube technique (TT). Methods We performed ABO isoagglutinin titration on samples received in a reference laboratory during a period of 2 months. A total of 134 tests for immunoglobulin G (IgG) titer and 116 for immunoglobulin M (IgM) for anti-A or anti-B were included in the study. Samples were processed for ABO isoagglutination titers by both TT and EMT by QWALYS-3 (DIAGAST, France). Microsoft Excel was used to compile data, for all calculations, and to draw graphs and plots. The number and percentage of cases within ±1, ±2, or ±3 titer difference (TT-EMT) were calculated. Results Median titers and their ranges obtained by EMT were higher or equal to those by TT for all IgM and IgG ABO-antibodies in all blood group (BGs), except anti-A IgM in (BG) O that was lower by EMT (32 [4:128]) than TT (48 [8:256]). One twenty one (121/134, 90.3%) cases of IgG titer showed an agreement by both methods (within ± one titer difference). One hundred seven cases (107/116, 92.2%) for IgM titer were within one titer difference by both the methods. Conclusion Results of titration by EMT-based automated instrument QWALYS-3 and conventional TT may vary by one titer dilution in the majority of cases. Use of consistent method for patient management is, therefore, advised.

A longitudinal study of convalescent plasma (CCP) donors and correlation of ABO group, initial neutralizing antibodies (nAb), and body mass index (BMI) with nAb and anti-nucleocapsid (NP) SARS-CoV-2 antibody kinetics: Proposals for better quality of CCP collections.

IntroductionLittle is known about the neutralizing (nAb) and binding antibody kinetics in COVID‐19 convalescent plasma donors, especially during the first 100 days after disease onset.Materials and MethodsA cohort of previously RT‐PCR positive (detected by nasopharyngeal swab during the acute phase), male convalescent patients, all with mild symptoms, were enrolled in serial blood sample collection for a longitudinal nAb titers and anti‐nucleocapsid (NP) antibodies (IgM, IgG and IgA) evaluation. NAbs were detected by a cytopathic effect‐based virus neutralization test (CPE‐based VNT), carried out with SARS‐CoV‐2 (GenBank: MT350282).ResultsA total of 78 male volunteers provided 316 samples, spanning a total of 4820 days of study. Although only 25% of donors kept nAb titers ≥160 within 100 days after the onset of disease, there was >75% probability of sustaining nAb titers ≥160 in volunteers whose initial nAb titer was ≥1280, weight ≥ 90 kg or obese, according to their body mass index (BMI), as evidenced by Kaplan–Meier analysis and Cox hazard regression (all p < .02). There was no correlation between the ABO group, ABO antibody titers and persistent high nAb titers. High IgG anti‐NP (S/CO ≥5.0) is a good surrogate for detecting nAb ≥ 160, defined by the ROC curve (sensitivity = 90.5%; CI95%: 84.5%–94.7%).ConclusionSelection of CCP donors for multiple collections based on initial high nAb titers (≥1280) or BMI ≥ 30 kg/m2 provides a simple strategy to achieve higher quality in CCP programs. High IgG anti‐NP levels can also be used as surrogate markers for high nAb screening.

Prevalence of ABO blood group phenotypes and antibody titers of the blood donor population in and around Puducherry

Background: For any blood transfusion services, knowing the prevalence and distribution of blood groups in their corresponding geographical area is essential. Hence, this study was done to know the prevalence and distribution of the ABO blood group and the antibody titer levels of blood donors at a premier tertiary care center in Southern India. Methodology: This was a cross-sectional study conducted over 22 months from September 2015 to June 2017 in the Department of Transfusion Medicine, JIPMER, Puducherry, among blood donors in a single tertiary care teaching hospital blood center. The ABO blood group and Rhesus factors (Rh) were determined by the antigen-antibody agglutination test by the test tube method. Titration of anti-A and anti-B antibodies was also done for selected “O” group donors by the doubling dilution technique in the tube method. Results: It was found that the most common blood group in our blood donor population was the “O” blood group with 11,904 (38.43%) followed by “B” 10,643 (34.37%), “A” 6,201 (20.02%), and “AB” 2,219 (7.17%). We had 4 Bombay blood group donors during the study period (0.01%). A titer of 1:32 was the most frequently encountered for IgM anti-A and anti-B antibodies; in Group “O” donors and IgG antibodies, it was 1:8. Conclusion: The prevalence of ABO in and around Puducherry is comparable to those published from other regions in Southern India, with the “O” group being the most common. The distribution of antibody titers for anti-A and anti-B is similar to other studies in India.

Impact of ABO-Incompatible Living Donor Kidney Transplantation on Patient Survival

Compared with recipients of blood group ABO-compatible (ABOc) living donor kidney transplants (LDKTs), recipients of ABO-incompatible (ABOi) LDKTs have higher risk for graft loss, particularly in the first few weeks after transplantation. However, the decision to proceed with ABOi LDKT should be based on a comparison of the alternative: waiting for future ABOc LDKTs (eg, through kidney paired exchange) or for a deceased donor kidney transplant (DDKT). We sought to evaluate the patient survival difference between ABOi LDKTs and waiting for an ABOc LDKT or an ABOc DDKT. Retrospective cohort study of adults in the Scientific Registry of Transplant Recipients. 808 ABOi LDKT recipients and 2,423 matched controls from among 245,158 adult first-time kidney-only waitlist registrants who did not receive an ABOi LDKT and who remained on the waitlist or received either an ABOc LDKT or an ABOc DDKT, 2002 to2017. Receipt of ABOi LDKT. Death. We compared mortality among ABOi LDKT recipients versus a weighted matched comparison population using Cox proportional hazards regression and Cox models that accommodated for changing hazard ratios over time. Compared with matched controls, ABOi LDKT was associated with greater mortality risk in the first 30 days posttransplantation (cumulative survival of 99.0% vs 99.6%) but lower mortality risk beyond 180 days posttransplantation. Patients who received an ABOi LDKT had higher cumulative survival at 5 and 10 years (90.0% and 75.4%, respectively) than similar patients who remained on the waitlist or received an ABOc LDKT or ABOc DDKT (81.9% and 68.4%, respectively). No measurement of ABO antibody titers in recipients; eligibility of participants for kidney paired donation is unknown. Transplant candidates who receive an ABOi LDKT and survive more than 180 days posttransplantation experience a long-term survival benefit compared to remaining on the waitlist to potentially receive an ABOc kidney transplant.