anti-A Titers Research Articles

Case study: Use of A2 and donor red blood cells for anti ABO a titer

ABO incompatibility (ABOi) is no longer an absolute contraindication for kidney transplantation. Recipients who are either blood group O or B have successfully received kidney transplants from donors who are blood group A, as long as their titer against the donor A antigen is low. Although the predominant A antigen subtype in the population is A1, less than 20% of blood group A individuals are of other subtypes, with weaker antigen expression, A2 being the most common of these. Accurate quantification of the amount of Anti A antibody titer in the recipient against the intended donor is important to determine compatibility for ABOi transplants. A review of the literature demonstrated that there is a high degree of technique variability, especially concerning the target cells utilized to determine such titers. Accordingly, we decided to use A2 and donor RBCs as well as our standard A1 RBCs in our assays, in order to determine the differences in titer when various A subtype cells are utilized as the target. Our case is a 54 year old male; 0% CPRA, blood group O recipient, whose donor was ABO typed as a non-A1. Flow T and B cell crossmatch negative. The transplant program decided to move forward with the ABO incompatible transplant since no other live donors were available. Determination of the Anti-A titer was as follows: Recipient sera was serially diluted with saline from 1:1 to 1:512. One drop of RBC suspension is added to 2 drops (100 ul) of each sera dilution. Three different titrations were performed using commercially produced A1 and A2 RBC as well as donor RBC. Tubes were incubated at RT for 30 minutes, centrifuged and agglutination macroscopically observed and recorded. Tubes were then incubated at 37C for 30 minutes, washed 4 times with saline, IgG added then centrifuged and agglutination recorded again. This procedure allows for determination of both IgM and IgG antibodies against blood group A antigens. IgG titers were 1:16 with A1 RBC; 1:8 with A2 RBC; and 1:8 with donor RBC. Our transplant program considers an IgG titer less than or equal to 1:8 acceptable and the transplant was performed. Recipient is out 11 weeks with no rejection episodes.

Anti-A/B Antibody Titers in Group O Healthy Donors in Hainan Province Area

To detect the IgM anti-A (B) and IgG anti-A (B) antibody titers of group O healthy donors in Hainan province area, to understand the distribution of O-type blood donor IgM and IgG antibody titers and to analyze the relationship between antibody titers, so as to provide experimental evidences for the safety and feasibility of urgent transfusion of uncrossmatched group O RBCs. Group O whole blood sample was collected from 80 volunteers blood donors. IgM antibody titrations was performed using the immediate spin (IS) tube, and IgG antibody titration were performed using the column agglutination technique with anti-human globulin (AHG). Using two-way ANOVA, paired t-test and correlation analysis, the different types of antibodies were compared. The IgM antibody titers distributed in 4-1 024, IgG antibody titer distributed in 2-2 048. Anti-A antibody titers of IgG were significantly higher than that of IgM anti-B, IgG anti-B and IgM anti-A titers (P < 0.05). There was a positive correlation bewteen IgM anti-A and anti-B, IgM anti-B and IgG anti-B, IgG anti-A and anti-B (P < 0.05). Group O blood donors have high antibody titers in Hainan province area, type O RBC suspensions should be first screened through screening the anti-A titer of IgG, so that can significantly improve the pass rate of O-type universal blood and reduce testing costs.

Therapeutic plasma exchange as a therapeutic modality for the treatment of IVIG complications

Intravenous immunoglobulin (IVIG) is used for the treatment of a number of inflammatory conditions. Hemolysis due to passive transfer of blood group antibodies is a well recognized complication of IVIG therapy. Therapy is largely supportive and consists of blood product support and hemodialysis. We report the use of therapeutic plasma exchange (TPE) as adjunct therapy for three patients with complications attributed to IVIG. Two patients had hemolysis attributed to IVIG; one patient was blood group A and the other blood group O. The third patient was an orthotopic heart transplant recipient with a type A donor heart, and anti-A antibodies detected after infusion of IVIG for suspected antibody mediated rejection. Two patients had anti-A titers available that decreased after initiation of plasma exchange. The blood group O patient with hemolysis had a gradual stabilization of hemoglobin and resolution of the positive DAT. TPE may be useful therapy for patients with severe hemolysis caused by IVIG or at risk for tissue damage by blood group antibodies.

Adverse effects of immunoglobulin G therapy: thromboembolism and haemolysis.

Adverse effects of immunoglobulin G therapy: thromboembolism and haemolysis.

Transplantation of ABO A2 Kidneys Into O Recipients: Do IgM Anti-A1 Titers Matter?

Purpose: Previous studies have shown successful kidney transplantation from ABO A2 donors into O or B recipients with low anti-A titers. To increase organ availability the new UNOS kidney allocation system (KAS) will incorporate A2 to B allocation. Criteria for A2 to O or B kidney transplants (txs) vary, from anti-A IgG titers (DTT treated serum) <1:8 (1) to anti-A IgM/G <1:16 or IgM/G > 1:8 with pre-tx plasmapharesis (2). Some report higher early graft failure with IgG titers >1:8, others found no correlation between IgG titers and acute rejection (AR) or allograft loss (1,2). The UNOS KAS does not provide anti-A titer criteria for A2 to B transplants. We report a high incidence of early AR or thrombotic microangiopathy (TMA) in A2 to O living donor (LD) transplant recipients with low IgG but high IgM/G titers. Methods: A retrospective review identified seven A2 to O LD kidney txs over 12 years at our institution. Both IgM/G and IgG (DTT treated) titers were reported. All patients (pts) received antibody induction and Tac/MMF/Pred maintenance. Results: Results are summarized in Table 1. All pts transplanted had pre-tx IgG anti-A titers <1:8. 4 pts had early allograft dysfunction with AR or TMA or both (mean 7 days post tx; range 2-16 d) with one graft loss POD 8 due to accelerated AR and cortical necrosis. Of these 4 pts, 3 had IgM/G titers >1:8 and the 4th had IgM/G=1:8. Of the three pts without rejection, one had IgM/G > 1:8.Table: No Caption available.Conclusions: Although good long term outcomes were achieved, our data show a high incidence of early AR and/or TMA and suggest caution in A2 to O kidney txs with high recipient anti-A IgM/G titers despite low IgG titers. Steps to lower anti-IgM/G pre-tx may reduce the risk of early AR or TMA. 1. Transpl 2005;80:75 2 Trans Proc 2001;33:3327 DISCLOSURES:Shaffer, D.: Grant/Research Support, Novartis, Astellas.

Subcutaneous bortezomib is highly effective for pure red cell aplasia after ABO‐incompatible haematopoietic stem cell transplantation

Subcutaneous bortezomib is highly effective for pure red cell aplasia after <scp>ABO</scp>‐incompatible haematopoietic stem cell transplantation

G372(P) Early relapse of atypical HUS following ABO incompatible living related paediatric renal re-transplant successfully treated with eculizumab

AimWe present a paediatric case of successful treatment of an early relapse of atypical haemolytic uraemic (aHUS) syndrome following ABO incompatible (ABOi) living related renal transplant using eculizumab. The female...

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.

Hemolysis After High Dose IVIG In Blood Group A Women With Alloimmune Thrombocytopenia

IntroductionHemolysis after IVIG infusion has been observed in clinical trials and case reports. Certain factors seem to place a patient receiving IVIG at higher risk for hemolytic anemia: 1) having blood type A, B, or AB and 2) receiving high doses of IVIG (≥ 2g/kg).IVIG contains isohemagglutinins that coat red blood cells and may cause red cell clearance by the RES (Table 1). Anti-A, Anti-B, and Anti-D titers have been detected in IVIG products at varying concentrations by different IVIG manufacturers. It has been suggested that Anti-A titers > 1:16 are more likely to cause clinically significant hemolysis and thus anemia in recipients.Table 1Anti-A Titer Levels by IVIG PreparationIVIG BrandAnti-A TiterGammagard liquid1:64Privigen 10%1:64Gamunex 10%1:32Octagam 10%1:8 - 1:32Gamimune-N1:8Octagam 5%1:2 - 1:8Carimune 9%1:4Table 2IVIG-Associated Hemolysis by Blood Type (BT)Blood TypePercent Experiencing HemolysisBlood Type Prevalence in USA61.9%40%B17.5%11%AB12.7%4%O4.8%45%15 summarized studies reported 63 patients who experienced hemolysis after IVIG infusion and showed the higher risk of non-group O recipients to hemolyze with IVIG:In the current study, we sought to explore the degree of anemia as related to ABO blood types in mothers treated with IVIG for fetal alloimmune thrombocytopenia (AIT). MethodsA retrospective chart review was conducted on 84 women who had received IVIG for AIT treatment during their pregnancy to increase the fetal platelet count. Women were randomized to receive IVIG 2g/kg/wk (arm A, n=43) or IVIG 1g/kg/wk + prednisone (arm B, n=41) starting at 20-30 weeks of gestation until delivery. One CBC per month was collected from each mother from the start of treatment until delivery. Hemoglobins and mean corpuscular volumes (MCVs) were tracked and development of anemia was compared among women with blood types (BT) A, B, AB and O in each treatment arm. Patients who non-randomly received IVIG 2g/kg/wk + prednisone together as rescuetreatment were excluded from this study. Results36 of the 84 women had hemoglobins less than 10 on at least one CBC during IVIG treatment. All 36 had MCV values in the normocytic range (80-100). The degree of anemia was significantly greater in Arm A (IVIG 2g/kg) than Arm B (IVIG 1g/kg + pred) (Fisher's exact test, p=0.016; table 3).Table 3Degree of Hemolysis among treatment armsArm A (IVIG 2g/kg/wk)Arm B (IVIG 1g/kg/wk + Prednisone 0.5 mg/kg/d)Hg<102412Hg≥101929Among women in arm A (IVIG 2g/kg), BT non-O had a significantly higher incidence of marked anemia (Hg<10) than those with BT O (Fisher's exact test, p=.001; table 4), with BT A having the highest number of women with Hg<10 (A=16, B=1, AB=1, O=4, unknown=2).There was no significant difference among women by blood type O (n=4) versus non-O (A=4,B=2,AB=0,unknown=2) in the incidence of anemia in arm B (IVIG 1g/kg + pred); both BT groups showed a low incidence of hemolysis (table 5).Table 4IVIG 2g/kg/wk (Arm A)Blood type OBlood type Non-OHg<10420Hg≥10136Table 5IVIG 1g/kg/wk + Pred (Arm B)Blood type OBlood type Non-OHg<1048Hg≥101415 ConclusionsPatients who were on 2g/kg/wk IVIG became substantially more anemic than those on the 1g/kg/wk IVIG + prednisone dose, which supports reported findings that higher dose (HD) IVIG is associated with a greater risk of anemia. Note: receiving IVIG 2g/kg/wk for multiple weeks is very high dose IVIG. In particular, those patients receiving HD IVIG who were BT A had a greater risk of developing a greater extent of anemia than those of blood type O. This finding is consistent with the hypothesis that blood-group specific antibodies in IVIG result in immune hemolysis primarily in BT A recipients because of the higher anti-A titers. Furthermore, while 1 g/kg/wk of IVIG is not “low dose”, the concomitant use of prednisone 0.5mg/kg/d may protect against development of a greater degree of anemia in these patients.IVIG is the standard of care treatment for AIT; however 1 g/kg/wk is known not sufficiently effective in severely thrombocytopenic fetuses (Berkowitz, OB-GYN 2006). Therefore we believe appropriate treatment of women whose previous babies did not have an ICH needs to be > 1g/kg/wk. Our study found that hemolytic anemia in non-O blood types may be an important side effect of 2g/kg/wk IVIG treatment, indicating that patient blood type should be considered when deciding which IVIG regimen to use. Disclosures:Bussel:Shionogi: Membership on an entity's Board of Directors or advisory committees, Research Funding; Eisai: Membership on an entity's Board of Directors or advisory committees, Research Funding; Ligand: Membership on an entity's Board of Directors or advisory committees, Research Funding; Immunomedics: Research Funding; IgG of America: Research Funding; Genzyme: Research Funding; Cangene: Research Funding; GlaxoSmithKline: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Research Funding; Sysmex: Research Funding; Symphogen: Membership on an entity's Board of Directors or advisory committees.

Bortezomib Is Highly Effective For Pure Red Cell Aplasia After ABO-Incompatible Hematopoietic Stem Cell Transplantation

Introduction Pure red cell aplasia (PRCA) is an uncommon complication of ABO-incompatible hematopoietic stem cell transplantation. It is characterized by anemia, reticulocytopenia and absence of erythroid precursors in a morphologically normal-appearing bone marrow. Most cases of PRCA resolve spontaneously within weeks to months. A small subset of patients has a protracted disease course requiring continued red blood cell (RBC) transfusions. There is no approved standard of care for PRCA. Tapering of immunosuppressives such as steroids and calcineurin inhibitors, plasma exchange, rituximab, and anti-thymocyte globulin have all been employed with varying success rates. We report a case of PRCA after ABO-incompatible transplant that responded remarkably to treatment with bortezomib. Case Presentation A 60 year old female received a non-myeloablative HLA-matched ABO-mismatched sibling donor transplant for lenalidomide-refractory myelodysplastic syndrome (5q-). She received fludarabine/busulfan conditioning and tacrolimus/methotrexate for GVHD prophylaxis. The donor was blood type A Rh-positive and the recipient was O Rh-positive. The patient's post-transplant course was complicated by delayed engraftment, thrombocytopenia and autoimmune hemolytic anemia. When seen at our institution 22 months post-transplant, she had transfusion-dependent anemia requiring RBC transfusions every 2-3 weeks and reticulocytopenia. Bone marrow biopsy showed erythroid aplasia and preserved hematopoiesis in other cell lines, dysplasia was absent and parvovirus testing was negative. The patient had evidence of complete engraftment based on short tandem repeat analysis. Blood typing reflected transfused type O Rh-negative RBCs. Neither A cells from the donor nor Rh-positive cells from the patient were detected. High titers of anti-A and anti-B isohemagglutinins were detected despite transfusion with washed RBCs to reduce passive transfer. She was treated with prednisone 60mg/day, rituximab 375 mg/m2 weekly x4 and methylprednisolone 1g weekly x6 without response. Eventually, all immunosuppressive medications were discontinued to induce a graft versus recipient response. Two subsequent bone marrow biopsies continued to show nearly absent erythropoiesis, and the rare erythroid cells present lacked the blood group A antigen. Since PRCA was thought to be due to the recipient's plasma cells making anti-A antibodies, bortezomib, a potent inducer of apoptosis in plasma cells, was initiated. Subcutaneous bortezomib 1.3 mg/m2 was administered weekly x4. The patient responded well to therapy. A month after completion of bortezomib, the patient's hemoglobin measured 12.1 g/dL, reticulocyte count was 174 x109/L and IgM and IgG anti-A titers were both &lt; 1. Bone marrow biopsy showed relative erythroid hyperplasia, and the majority of the erythroid precursors expressed blood group A. The patient continues to do well and at the time of her most recent evaluation, her hemoglobin was 13.9 g/dL. She has also remained transfusion-independent. Discussion PRCA after major ABO-incompatible transplant is thought to be caused by persistence of recipient plasma cells that continue to secrete anti-donor isohemagglutinins. Antibody titers may remain elevated for a longer duration in patients receiving non-myeloablative preparatory regimens. Bortezomib is a proteasome inhibitor that selectively induces apoptosis in plasma cells. Bortezomib has been used successfully to treat anti-body mediated rejection in both renal and liver transplant patients. A case of PRCA following ABO-mismatched hematopoietic transplant that was successfully treated with IV bortezomib has also been reported. To our knowledge, this is the first reported case of isohemagglutinin-mediated PRCA after ABO-mismatched transplant that responded favorably to subcutaneous bortezomib. Limitation The lack of long-term follow-up data precludes any assessment about the durability and persistence of response to bortezomib. Conclusion Bortezomib is an effective treatment for patients with PRCA mediated by residual host isohemeagglutinins after ABO-incompatible hematopoietic transplantation. Disclosures: Off Label Use: Our presentation describes the use of bortezomib for treatment of pure red cell aplasia after ABO-incompatible hematopoeitic stem cell transplantation. Vercellotti:Sangart Inc.: Research Funding; Seattle Genetics, Inc.: Research Funding.

Maternal alloimmunization as a risk factor of haemolytic disease of the foetus and newborn in Owerri metropolis, Nigeria

Blood group incompatibility between mother and her foetus which usually arises as a result of heterospecific pregnancy causes haemolytic disease of the foetus and newborn (HDN). Five hundred (500) pregnant women attending antenatal clinic at Federal Medical Centre (FMC), Owerri were recruited for this research work. They were aged between 17 and 40 years. All subjects gave informed consent to participate in the study. They were screened for ABO blood groups RhD status and immune alloantibodies. Anti-A and anti-B from group O subjects compared with anti-A from group B women and anti-B from group A women among the trimester. The rate of RhD negativity (5.4%) was significantly lower than the RhD positively (94.6%) (P<0.005). Haemolysin tests were positive in 110 (22.0%) cases and negative in 390 (78.0%) cases. Group O women produced more alpha and / or beta haemolysins than either A or B women (P<0.005). Anti-A titres were higher in the trimesters than anti-B. Indirect antiglobulin test (IAT) was positive in 12(80.0%) cases among ABO group and positive in 3(20.0%) cases among RhD group. There was a higher prevalence of ABO HDN than RhD HDN in the ratio of 3:1 respectively. This study illustrates the presence of immune alloantibodies in the sera of allominiunized pregnant women and the rise in the antibody titres has helped to identify pregnancies at risk of foetal and neonatal HDN. Anti-D immunoprophylaxis has made HDN caused by sensitization to the D-antigen a preventable disease and prenatal deaths from allominization by immunoprophylaxis has been primarily responsible for the dramatic reduction in the diseases, although changes in family size and the quality of prenatal care have also contributed.

Successful Treatment of Severe ABO Antibody-Mediated Rejection Using Bortezomib: A Case Report

BackgroundOur program for ABO-incompatible renal transplantation includes antigen-specific immunoadsorption (extracorporeal columns with the A or B trisaccharides), rituximab, and standard maintenance immunosuppression. Anti-A or -B titers ≤8 in the indirect antiglobulin test (IAT) against panel A1 or B RBC are acceptable for transplantation. Case ReportA previously healthy, 15-month-old girl was diagnosed with Wilms' tumor and proteinuria. Denys–Drash syndrome was confirmed. Bilateral nephrectomy was performed. At 3.5 years of age she received an ABO-incompatible renal transplant from her father (A1 to O). The anti-A titers before transplantation were low. She was treated preoperatively with rituximab, immunoadsorption, immunoglobulin and mycophenolate mofetil (MMF). The maintenance immunosuppression protocol included basiliximab, tacrolimus, MMF, and prednisolone. The initial postoperative course was uncomplicated with rapid normalization of serum creatinine. The anti-A titers started to increase on postoperative day 5 (8 NaCl/16 IAT). Despite daily immunoadsorptions the titers rose to 1024 NaCl/1024 IAT on day 9. Renal function deteriorated and hemodialysis was started. A renal biopsy on day 9 showed acute severe antibody-mediated rejection. Additional treatment with bortezomib was given and after 2 doses the titers started to decline, renal allograft function improved and hemodialysis was stopped. On day 21 posttransplant the titers went down, creatinine was 28 μmol/L, and no more immunoadsorptions were performed. ConclusionBy using bortezomib, we were able to successfully reverse a severe ABO antibody-mediated rejection.

Blood Group A Transgenic Mice: A Model for ABO-Incompatible (ABOi) Heart Transplantation (HTx)

Purpose Our group demonstrated that infant ABOi HTx results in development of immune tolerance to donor ABO antigen(s). We recently developed mice transgenic for expression of A- and H-glycosyltransferases (AH-Tg, C57BL/6 (B6) background). By lectin staining, AH-Tg mice express blood group A-antigen on vascular endothelium of solid organs including heart. Human ‘A into O’ HTx can be approximated using AH-Tg mice as donors and B6 wild-type (WT) mice as recipients. Herein we sought to characterize ‘natural’ and induced anti-A antibodies (Abs) in WT mice and binding to A-expressing AH-Tg hearts, and to investigate AMR following transplantation of AH-Tg heart grafts into WT mice with high anti-A titre. We hypothesize that serum from WT mice with high anti-A titre will bind to AH-Tg cardiac tissue, and that AH-Tg heart grafts will undergo AMR following transplantation into WT recipients with high anti-A Abs. Methods and Materials Juvenile WT B6 mice were induced to produce anti-A Abs by i.p. injection of blood group A red blood cells. Sera from WT and AH-Tg mice of different ages were assessed for anti-A Ab by hemagglutination assay. Binding of serum anti-A Abs to AH-Tg hearts was determined by immunohistochemistry (IHC). WT mice with high anti-A titres received AH-Tg heart transplants; AMR was assessed by IHC. Results Increasing anti-A Abs were detected with age in WT mice (n=108). No AH-Tg mice had detectable anti-A Abs (n=19). Using a commercial anti-A Ab, we detected A-antigen on vascular endothelium of hearts, kidneys, livers, and lungs from AH-Tg mice. Serum from older WT mice with natural anti-A Abs or from younger A-antigen-sensitized WT mice bound to AH-Tg but not WT cardiac tissue. Conclusions This study provides insight into the development of anti-A Abs in WT mice and confirms A-antigen expression on AH-Tg cardiac endothelium by serum anti-A Abs. Studies are ongoing to examine AMR following transplantation of AH-Tg heart grafts into WT mice with high anti-A titres.

Belatacept Used as Rescue Maintenance Immunosuppression in ABO-Incompatible Living Donor Kidney Transplant

Introduction: Belatacept (Nulojix) is the first T-cell co-stimulation blocking immunosuppressive agent licensed for use in transplantation. It is an effective alternative to ciclosporin in ABO and HLA-antibody compatible adult kidney transplantation. Here we describe a patient successfully maintained on Belatacept following an ABO and HLAantibody incompatible live donor renal transplant. Case report: The patient is a 30-year old male diagnosed with IgA nephropathy in 2008. He became dialysis dependent in January 2011. In September 2011 he received a 2-1-1 mismatched transplant from his wife. He was ABO group O with an anti-A tire of 1:256 against the group A1 donor. CDC and flow cross matching were negative but HLA A3 and A11 DSA were detected by Luminex with MFI of 4754 and 2567 respectively. There was no known allosensitizing stimulus. Immunosuppression comprised IV Rituximab 500mg 3 weeks prior to transplantation, 7 cycles of immunoabsorption and induction with 30mg Alemtuzumab, followed by Tacrolimus, Mycophenolate Mofetil (MMF) and prednisolone. On the day of transplant anti-A titre was 1:8 and DSA undetectable. Surgery was uncomplicated with primary graft function. On post-operative day 5 serum creatinine (SCr) reached 240mmol/L, but on day 7 rose to 289mmol/L. Biopsy demonstrated severe thrombotic microangiopathy (TMA) with multiple microthrombi in glomerular afferent arterioles and capillaries. C4d was diffusely positive, but without peritubular capillaritis, glomerulitis or evidence of T-cell mediated rejection. Anti-A titre was 1:4 and DSA undetectable. A diagnosis of Tacrolimus-related TMA was made, without systemic features of TMA. Tacrolimus was discontinued, 10 cycles of plasma exchange with FFP replacement administered, and sirolimus added to MMF and prednisolone. SCr fell to 140mmol/L. On day 36, the patient developed a swollen leg ipsilateral to his graft. SCr was stable at 136mmol/L but there was significant proteinuria with a urinary ACR of 198mg/mol. CT demonstrated a lymphocele compressing the external iliac vessels. Surgical drainage and fenestration of the collection into the peritoneal cavity resulted in immediate resolution of both the lymphocele and the swollen leg. Both proteinuria and lymphocele were attributed to Sirolimus, which was discontinued. Since Tacrolimus was contraindicated Belatacept was added, initially as a monthly infusion (10mg/kg). Since commencing Belatacept, proteinuria has resolved (ACR 14.5) and SCr remained stable at 130mmol/L. DSA have returned to pre-transplant levels, and anti-A titre is 1:64. Immunosuppression comprises Belatacept 5mg/kg monthly, MMF 1000mg BD and prednisolone 5mg OD. Conclusion: Belatacept use was necessitated by serious adverse reactions to both Tacrolimus and Sirolimus. This case demonstrates the utility of Belatacept as rescue maintenance immunosuppression in an ABO and HLA antibody incompatible transplant.

Betwixt Scylla and Charybdis

Betwixt Scylla and Charybdis

Rescue Kidney Paired Donation as Emergency Salvage for Failed Desensitization

Rescue Kidney Paired Donation as Emergency Salvage for Failed Desensitization

Titers of ABO antibodies in group O blood donors

Overt hemolysis from the transfusion of ABO incompatible plasma containing high titer anti-A or anti-B is a rare event. Plasma from group O donors and the transfusion of single donor platelets are most often associated with these reactions when transfused to group A or AB recipients. Several studies over the years have evaluated donor ABO antibody class, titer, and subclass in an effort to understand the breadth of the problem and reduce or eliminate this potentially serious immune complication of transfusion. In this regard, de Franca et al.(1) in this issue of the Revista Brasileira de Hematologia e Hemoterapia underscore the lack of a national standard of practice to guide the transfusion of incompatible ABO plasma transfusions. They point out that seminal work, started more than 2 decades ago, has yet to set policy and safety guidelines with the use of plasma that potentially contain life-threatening levels of anti-A or anti-B.(2) de Franca et al. examined over 5% of their blood donors included males and females across all age groups in an effort to understand which donors pose the biggest risk for the transfusion of high-titer anti-A or anti-B. Not surprising they found that ABO antibody titers decrease with age, with older males having the lowest titers by age 50. Cumulatively, nearly 1 in 10 plasma contain anti-A titers ≥ 128. Their work suggests that targeting ABO incompatible plasma and platelets from older males would lower the risk, if one assumes titers over 64 by the doublingdilution method (generally titers = 100 are regarded as critical) pose significant risk of hemolysis. However, there is still a 1:20 (5.3%) chance that plasma from males over 50 will contain a titer ≥ 128. Thus, targeting sex and specific age groups as surrogate markers for the transfusion of ABO incompatible platelets could hardly be considered safe practice, although it would be a step in the right direction. The lack of a standardized test and the impact on blood product availability is having an effect on the ability to drive policy and develop meaningful guidelines. Methodology appears to be a major issue. de Franca et al. used direct agglutination, however, other studies have used a test tube indirect antiglobulin test (IAT), gel microcolumn agglutination in an IAT, and flow cytometry to measure the amount of anti-A,B, anti-A and anti-B. The measurement of anti-A,B does not appear to provide any additional information on titers when compared to anti-A (de Franca et al.(1) Table 1). One problem with defining a standard may be the lack of studies necessary to correlation these methods and thus an agreement on the critical titer for which non-ABO matched platelet transfusions should be avoided. European blood centers have addressed the issue of titers and have identified low-risk titers for ABO incompatible plasma transfusions. It is important to establish critical ABO antibody titers by population (national), using the most clinically relevant method, since it appears that diet and ethnicity may result in significant differences in titers.(3,4) Performing population estimates for anti-A and anti-B levels across blood donors determines the frequency of high titers and help estimate the cost of implementing a nationalized testing policy. de Franca et al. have made a significant contribution in this regard. However, the challenge remains to quantify the impact that such a policy will have on the provision of plasma containing platelet products to recipients.(5)

High anti-A titres may not preclude ABO-incompatible renal transplantation: an autoantibody could be the culprit

ABO-incompatible live donor renal transplantation is a growing field. To avoid hyperacute rejection, pre-operative ABO antibody titres should be < 8. There are a number of therapeutic measures used to reduce these titres if they are high. This case report describes a patient initially found to have an extremely high anti-A IgG titre (512). The high titre results were concomitant with a positive atypical antibody screen, which showed no specificity on identification. A strategy to assess true titre levels and remove sub-clinical autoantibodies was devised, leading to successful transplantation.

Investigation into A antigen expression on O2 heterozygous group O–labeled red blood cell units

There are two principal types of group O alleles; deletional alleles feature 261delG leading to nonfunctional truncated protein. Nondeletional alleles have the consensus guanosine at residue 261. The major nondeletional allele, O2, encodes full-length protein with Gly268Arg. While reports vary, O2 has been proposed to encode weakly functional A-glycosyltransferase (GTA). The main objective of this study was to evaluate if GTA activity is detectable in O2 donors. Donor samples from Pittsburgh and Lund were ABO typed by automated methods. DNA was extracted from 779 group O donors whose red blood cells (RBCs) were available for transfusion. ABO genotyping identified those with O2 alleles. The following tests were performed on randomly selected O2 samples (number): adsorption-elution with anti-A (3), flow cytometry (15), plasma enzyme activity (4), and attempts to convert group O RBCs to A (2) with O2 plasma and titration of plasma anti-A/-A1 (3). Forty O2-heterozygous donors were identified (5.1%). Adsorption-elution and sensitive flow cytometry did not reveal A antigens on O2 RBCs. Plasma enzyme analysis failed to show GTA activity above baseline; O2 plasma was unable to add measurable A antigens to O RBCs. Titers of anti-A/-A1 appeared reduced in O2 plasma but did not cause ABO typing discrepancies. No immediate hemolysis or adverse reactions were reported following transfusion of O2 RBCs to six evaluable group O recipients. Other than lower plasma anti-A titers, GTA activity was not found in these O2 samples. Neither automated blood grouping discrepancies nor clinical problems related to transfusing these O2 units were observed.

Reducing the variation in performance of antibody titrations.

Abstract Background.—Antibody titration is difficult to standardize. We investigated whether a detailed, uniform procedure for antibody titration would reduce variation in both tube-based and gel card titres in an international study. Methods.—Laboratories (n = 35) tested proficiency testing material provided by the College of American Pathologists each according to (i) their routine method; (ii) a detailed, uniform method; and (iii) the uniform method titrating the serum sample against a red cell of specified phenotype (D+ C− c+ E+ e− for anti-D; A1 for anti-A) instead of the red cell of the same phenotype provided in the proficiency testing kit. Uniform method results were reported with 1+ and w+ end-points. Paired statistical analyses of variance were conducted using the F-test. Results.—The variance between laboratories was not significantly reduced with the uniform method using a 1+ end-point. However, a statistically significant reduction in the variance of anti-D and anti-A titres by the tube-based...