BACKGROUND: Pure red cell aplasia (PRCA) following allogeneic hematopoietic stem cell transplantation (allo-HSCT) with ABO major incompatibility is characterized by transfusion dependent anemia. No standard treatment existed for PRCA following allo-HSCT yet.
METHODS: We conducted a retrospective study, and reported our experience with the use of avatrombopag and lower dose rituximab to treat five patients with PRCA subsequent to major ABO-incompatible allo-HSCT.
RESULTS: Five cases of PRCA were identified from 72 patients who underwent allo-HSCT with major or bidirectional ABO mismatch. Cumulative incidence at Day +60 was 6.9% (5/72) at our center. All donor and recipient blood groups were A+  and O+ , respectively. In the first three cases we reported, patients received erythropoietin, plasma exchange, and donor lymphocyte infusion, but none of them had any effect. After 4 weeks of treatment with low dose rituximab (100 mg/week) combined with avatrombopag (40 mg/day), favorable outcomes were obtained. According to the aforementioned experience, Cases 4 and 5 were administered low-dose rituximab and avatrombopag in 3 months after transplantation, and erythroid response was observed on 3 weeks after treatment. Our patients tolerated low-dose rituximab and avatrombopag well and experienced rapid efficacy, with a median duration of 3 weeks. Furthermore, no severe infection or thrombocytosis necessitated a dose adjustment.
CONCLUSIONS: Low-dose rituximab and avatrombopag may be an effective treatment for patients with PRCA after major ABO-incompatible allo-HSCT. The patients should be treated at least 90 days post transplantation if conventional erythropoietin therapy fails.

OBJECTIVE: The current study aimed to examine the incidence of perioperative infections and graft viability in ABO-compatible and ABO-incompatible renal transplant recipients.
METHODS: We included 643 living donor renal transplant recipients registered in the Michinoku Renal Transplant Network from 1998 to 2021. Patients were divided into the ABO-compatible and ABO-incompatible kidney transplantation groups. We compared the characteristics of the two groups and evaluated the incidence of postoperative viral infections (cytomegalovirus and BK virus), graft loss-free survival, and overall survival between the two groups.
RESULTS: Of 643 patients, 485 (75%) and 158 (25%) were ABO-compatible and ABO-incompatible renal transplant recipients, respectively. Postoperative viral infections, rituximab use, and plasma exchange were significantly more common in ABO-incompatible than in ABO-compatible transplant recipients. However, there were no significant differences in terms of other background characteristics. The ABO-incompatible group was more likely to develop viral infections than the ABO-compatible group. Graft loss-free survival and overall survival did not significantly differ between the two groups. According to the multivariate Cox regression analysis, ABO compatibility was not significantly associated with graft loss-free survival and overall survival.
CONCLUSIONS: Although the incidence of postoperative viral infections in ABO-incompatible renal transplant recipients increased, there was no significant difference in terms of rejection events, graft loss-free survival, and overall survival.

Hemolysis is a positive agglutination reaction and is primarily associated with high anti-A or anti-B antibody titers. This high titer may result in no agglutination due to the \"prozone\" phenomenon. Platelet concentrate of high titer has an adverse effect on the recipient of the non-identical ABO blood group. Similarly, the blood products with higher titers of isoagglutinin have recently increased the incidence of intravenous immunoglobulins-related hemolysis. In this Asian subcontinent, the impact of O blood donors with high antibody titers or ABO incompatible platelets is hardly addressed. Blood was collected from two healthy donors and subjected to blood grouping as done routinely. Hemolysis was observed in the reverse grouping with the \"B-\"cell. Blood grouping was repeated with the conventional tube technique (CTT) where there was no agglutination with the \"B\"-cell. Suspecting the \"prozone\" phenomenon, serial dilution of anti-B was done by CTT, and the titer was found to be 1:256 and 1:128 in both cases. Then, the reverse grouping was repeated with a diluted serum (1:8), and the blood group was confirmed to be A RhD-positive and O RhD-positive, respectively. The absence of agglutination in a reverse grouping is not only an indicator of weak antibody but also a presentation of the \"prozone\" phenomenon. This could be differentiated by doing the titer of isoagglutinin. Hemolysis due to high agglutinin levels should be documented and evaluated, and blood components should be properly labeled to ensure that the product is transfused to the same blood group patients.

BACKGROUND: Clinical factors predicting graft survival (GS) after ABO-incompatible (ABOi) liver transplantation (LT), and differences between recipients with and without hepatocellular carcinoma (HCC) are unclear.
OBJECTIVE: To analyze the impact of serial serum tacrolimus trough concentration in recipients with or without HCC) in ABOi living-donor liver transplantation (LDLT).
METHODS: We analyzed a historical cohort of 89 recipients who underwent ABOi LDLT, including 47 patients with HCC.
RESULTS: The 1-, 3-, 5-, and 10-year GS rates were 85.9%, 73.3%, 71.4%, and 71.4%, respectively, and there were no significant differences between HCC and non-HCC recipients. In multivariate Cox-regression analyses, tacrolimus trough concentrations below 5.4 ng/mL at 24 wk post-LT, in addition to the antibody-mediated rejection (AMR) were associated with poor-graft outcomes. In HCC patients, AMR [hazard ratio (HR) = 63.20, P < 0.01] and HCC recurrence (HR = 20.72, P = 0.01) were significantly associated with poor graft outcomes. HCCs outside Milan criteria, and tacrolimus concentrations at 4 wk post-LT > 7.3 ng/mL were significant predictive factors for HCC recurrence. After propensity score matching, patients with high tacrolimus concentrations at 4 wk had significantly poor recurrence-free survival.
CONCLUSIONS: Elevated tacrolimus levels at 4 wk after ABOi LDLT have been found to correlate with HCC recurrence. Therefore, careful monitoring and control of tacrolimus levels are imperative in ABOi LT recipients with HCC.

Kidney transplantation from blood type A2/A2B donors to type B recipients (A2→B) has increased dramatically under the current Kidney Allocation System (KAS). Among living donor transplant recipients, A2-incompatible transplants are associated with an increased risk of all-cause and death-censored graft failure. In light of this, we used data from the Scientific Registry of Transplant Recipients from December 2014 until June 2022 to evaluate the association between A2→B listing and time to deceased donor kidney transplantation (DDKT) and post-DDKT outcomes for A2→B recipients. Among 53 409 type B waitlist registrants, only 12.6% were listed as eligible to accept A2→B offers (\"A2-eligible\"). The rates of DDKT at 1-, 3-, and 5-years were 32.1%, 61.4%, and 72.1% among A2-eligible candidates and 14.1%, 29.9%, and 44.1% among A2-ineligible candidates, with the former experiencing a 133% higher rate of DDKT (Cox weighted hazard ratio (wHR) = 2.192.332.47; P < .001). The 7-year adjusted mortality was comparable between A2→B and B-ABOc (type B/O donors to B recipients) recipients (wHR 0.780.941.13, P = .5). Moreover, there was no difference between A2→B vs B-ABOc DDKT recipients with regards to death-censored graft failure (wHR 0.771.001.29, P > .9) or all-cause graft loss (wHR 0.820.961.12, P = .6). Following its broader adoption since the implementation of the kidney allocation system, A2→B DDKT appears to be a safe and effective transplant modality for eligible candidates. As such, A2→B listing for eligible type B candidates should be expanded.

Kidney transplantation is considered an ideal treatment for end-stage renal disease (ESRD) because it provides a longer and better quality of life than dialysis. ABO-incompatible (ABO-I) kidney transplantation relies on two principles: (i) removal of antibodies from a blood group; and (ii) inhibition of reappearance of blood group antibodies by intensifying the induction and maintenance of immunosuppression. This systematic review aimed to analyze the success and safety of ABO-I live-donor kidney transplantation.
Databases, including Google Scholar, PubMed, Embase, Web of Science, and Medline were searched. Search duration was from the database establishment to December 2022. A thorough search was performed for relevant studies investigating the success and safety of ABO-I live-donor kidney transplantation. Two investigators independently extracted literature information and assessed the quality of the included studies. Heterogeneity test was performed using Cochrane\'s Q and chi-squared tests. All statistical analyses were performed using R software (version 4.2.1).
The search for relevant literature in the five electronic databases yielded 1238 articles. Of the 1238 articles, only 15 were included. Meta-analysis of outcomes from five studies showed a survival rate of 0.93 (95% confidence interval [CI]: 0.88 to 0.97, P < 0.001) after ≥3 years, while outcomes from 12 studies revealed a short-term patient survival rate of 0.94 (95% CI: 0.92 to 0.96, P = 0.75). In contrast, long- and short-term graft survival rates were 0.89 (95% CI: 0.75 to 0.96, P < 0.001) and 0.94 (95% CI: 0.90 to 0.97, P < 0.001), respectively. Incidence rates of infectious, surgical, and medical complications were 0.31 (95% CI: 0.22 to 0.41, P < 0.001), 0.12 (95% CI: 0.05 to 0.25, P < 0.001), and 0.38 (95% CI: 0.17 to 0.66, P < 0.001), respectively.
Good long- and short-term patient outcomes and graft survival rates were observed after ABO-I kidney transplantation. Similarly, the safety of performing kidney transplantations from living donors with ABO-I blood groups was established by the results of the current meta-analysis. Therefore, ABO-I live-donor kidney transplantations should be encouraged to reduce the time recipients spend on waiting lists and supplement the existing paired-exchange donor program.

The current approach for preventing hemolysis of red blood cells (RBCs) in major ABO-incompatible bone marrow (BM) grafts after infusion is to deplete RBCs from BM products before transplantation. Traditionally, manual density separation (MDS) using Ficoll-Hypaque (Cytiva Sweden AB, Uppsala, Sweden has been used to accomplish RBC depletion. This process yields good CD34+ cell recovery, but it requires open manipulation and is labor-intensive and time-consuming. We hypothesized that an alternative automated method using Haemonetics Cell Saver 5+ (Haemonetics Corporation, Boston, MA, USA) would offer equivalent RBC depletion and CD34+ cell recovery. Small marrow volumes from pediatric donors can be processed using Cell Saver (CS) without adding the third-party RBCs necessary for other automated methods.
This retrospective analysis comprised data from 58 allogeneic BM grafts. RBC depletion and CD34+ cell recovery from BM using MDS (35 grafts) were compared with CS (14 grafts). Nine products underwent RBC depletion using CS with Ficoll (CS-F) when RBC volume was less than 125 mL.
Linear regression analysis of log transformation of CD34+ cell recovery adjusted for log transformation of both baseline CD34+ cell content and baseline total volume showed no significant difference between MDS and CS (estimated coefficient, -0.121, P = 0.096). All products contained an RBC volume of less than 0.25 mL/kg post-processing. CD34+ cell recovery with CS-F was comparable to MDS and CS and suitable for pediatric recipients of allogeneic hematopoietic cell transplantation.
We provide evidence that an automated method using Haemonetics Cell Saver 5+ achieves RBC depletion and CD34+ cell recovery comparable to MDS when adjusting for baseline factors.

BACKGROUND: Pathologic diagnosis of antibody-mediated rejection (ABMR) in ABO-incompatible (ABOi) transplantation patients is often challenging because patients without ABMR are frequently immunopositive for C4d. The aim of this study was to determine whether C4d positivity with microvascular inflammation (MVI), in the absence of any detectable donor-specific antibodies (DSAs) in ABOi patients, could be considered as ABMR.
METHODS: A retrospective study of 214 for-cause biopsies from 126 ABOi kidney transplantation patients was performed. Patients with MVI score of ≥2 and glomerulitis score of ≥1 (n = 62) were divided into three groups: the absolute ABMR group (DSA-positive, C4d-positive or C4d-negative; n = 36), the C4d-positive group (DSA-negative, C4d-positive; n = 22), and the C4d-negative group (DSA-negative, C4d-negative; n = 4). The Banff scores, estimated glomerular filtration rates (eGFRs), and graft failure rates were compared among groups.
RESULTS: C4d-positive biopsies showed higher glomerulitis, peritubular capillaritis, and MVI scores compared with C4d-negative specimens. The C4d-positive group did not show significant differences in eGFRs and graft survival compared with the absolute ABMR group.
CONCLUSIONS: The results indicate that C4d positivity, MVI score of ≥2, and glomerulitis score of ≥1 in ABOi allograft biopsies may be categorized and treated as ABMR cases.

ABO-incompatible transplantation has been successfully performed in the kidney and liver. However, lungs are subject to strong rejection and are vulnerable to infection because they are directly exposed to air. Therefore, lung transplantation from organs with incompatible blood types has been considered a significant challenge. Due to the severe shortage of donors, ABO-incompatible lung transplantation might be a viable method to save critically ill patients with end-stage respiratory diseases. Herein, we review the worldwide published reports about both minor and major ABO-incompatible lung transplantations. In North America, major ABO-incompatible lung transplants have been performed in cases with clerical errors in blood typing. But they were successful with additional treatments following the protocol for ABO-incompatible transplants in other organs (multiple plasma exchanges and additional immunosuppressive therapy such as anti-thymocyte globulin administration). In Japan, major ABO-incompatible living-donor lobar lung transplantations have also been performed successfully when the recipient does not have an ABO antibody against the donor. This unique situation sometimes occurs when the recipient undergoes hematopoietic stem cell transplantation before lung transplantation, in which the recipient\'s blood type changes after hematopoietic stem cell transplantation. One infant and one adult had successful intentional major ABO-incompatible lung transplantation with both induction therapy and aggressive maintenance antibody-depletion therapy. Furthermore, an experimental antibody-depletion study has also been conducted to overcome ABO incompatibility. Even though intentional major ABO-incompatible lung transplantation has rarely been performed, several significant pieces of evidence have been accumulated to prepare for ABO-incompatible lung transplantation in selected cases. In the future, this challenge can potentially expand the donor organ pool and lead to improvements in the fairness of organ allocation.

UNASSIGNED: Liver transplantation (LT) using ABO-incompatible (ABOi) grafts can extend the donor pool to a certain extent and hence reduce the waiting time for transplantation. However, concerns of the impending prognosis associated with this option, especially for patients with liver failure and higher model for end-stage liver disease (MELD) scores, who tend to be more fragile during the waiting period before LT.
UNASSIGNED: Recipients undergoing LT for acute-on-chronic liver failure or acute liver failure were retrospectively enrolled at four institutions. Overall survival was compared and a Cox regression analysis was performed. Propensity score matching was performed for further comparison. Patients were stratified by MELD score and cold ischemia time (CIT) to determine the subgroups with survival benefits.
UNASSIGNED: Two hundred ten recipients who underwent ABOi LT and 1,829 who underwent ABO compatible (ABOc) LT were enrolled. The 5-year overall survival rate was significantly inferior in the ABOi group compared with the ABOc group after matching (50.6% vs. 75.7%, p<0.05). For patients with MELD scores ≤30, using ABOi grafts achieved a comparable overall survival rate as using ABOc grafts (p>0.05). Comparison of the survival rates revealed no statistically significant difference for patients with MELD scores ≥40 (p>0.05). For patients with MELD scores of 31-39, the overall survival rate was significantly inferior in the ABOi group compared with the ABOc group (p<0.001); however, the rate was increased when the liver graft CIT was<8 h.
UNASSIGNED: For recipients with MELD scores ≤30, ABOi LT had a prognosis comparable to that of ABOc LT and can be regarded as a feasible option. For recipients with MELD scores ≥40, ABOi should be adopted with caution in emergency cases. For recipients with MELD scores of 31-39, the ABOi LT prognosis was worse. However, those patients benefited from receiving ABOi grafts with a CIT of <8 h.