A reassessment of ABO incompatibility in pediatric liver transplantation

Outcomes after ABO incompatible pediatric liver transplantation are comparable to ABO identical/compatible transplant

Background

ABO incompatible (ABOi) liver transplantation (LT) was initially associated with a higher incidence of vascular, biliary, and rejection complications and a lower survival than ABO compatible (ABOc) LT. Various protocols have been proposed to manage anti-isohemagglutinin antibodies and hyperacute rejection. We present our experience with a simplified protocol using only plasmapheresis.

Methods

A retrospective review of all patients who received an ABOi LT at our institution was performed. Comparisons were made based on era (early: 1997-2008, modern: 2009-2020) and severity of disease (status 1 vs. exception PELD at transplant). A pair-matched comparison was done to patients who received an ABOc LT. p < 0.05 was considered significant.

Results

17 patients received 18 ABOi LT (3 retransplants). Median age at transplant was 7.4 months (1.1-28.9). 66.7% patients were listed as status 1. Hepatic artery thrombosis (HAT) occurred in one patient (5.6%), there were 2 cases of portal vein thrombosis (PVT) (11.1%), and 2 biliary strictures (11.1%). Patient and graft survival improved in the ABOi modern era, although not significantly. In the pair-matched comparison, complications (HAT p = 0.29; PVT p = 0.37; biliary complications p = 0.15) and survival rates were similar. Patient and graft survivals were 100% in the non-status 1 ABOi patients compared to 67% (p = 0.11) and 58% (p = 0.081) respectively for patients who were transplanted as status 1.

Conclusion

ABO incompatible liver transplants in infants with a high PELD score have excellent outcomes. Indications for ABO incompatible transplants should be liberalized to prevent deaths on the waiting list or deterioration of children with high PELD scores.

Clinical outcomes after ABO-incompatible liver transplantation: A systematic review and meta-analysis

BACKGROUND

ABO-incompatible liver transplantation (ABOi-LT) is increasingly used to overcome donor shortage. Evidence about disadvantage and advantage in comparison with ABO-compatible liver transplantation (ABOc-LT) needs to be performed in the early and late periods. Herein, We compared the short-term and long-term outcomes between ABOi-LT and ABOc-LT cohorts.

METHODS

We performed a meta-analysis based on the observation studies which included outcomes at ≥1 year after ABOi-LT and ABOc-LT procedures, based on the MEDLINE (via Pubmed), the Cochrance Central Register of Controlled Trials (CENTRAL), and EMBASE (via Ovid) systems. Two researchers independently screened each study according to the pre-established inclusion and exclusion criteria to assess the quality of each study and extracted data from published studies. The primary outcome indicators were all-cause mortality and graft survival at 1, 3 and 5 years after transplantation. In the meta-analysis, we based on the value of heterogeneity using a fixed-effect and a random-effect. A fixed-effect model was used if the value of I2 was less than or equal 50%; and a random-effect model was used if the value of I2 was greater than 50%.

FINDINGS

Out of 335 identified records, 29 records with 10,783 patients with liver transplants; 2137 of them were ABOi-LTs and the remaining 8646 were ABOc-LTs. There was no significant difference at 1-year, 3-year, and 5-year in all-cause mortality, death-censored graft survival and complication incidence rate between ABO-incompatible living donor liver transplantation (ABOi-LDLT) group and ABO-compatible living donor liver transplantation (ABOc-LDLT) group. Compared with ABO-compatible deceased donor liver transplantation (ABOc-DDLT), ABO-incompatible deceased donor liver transplantation (ABOi-DDLT) had a higher 1-year all-cause mortality, and the value of totally pooled odds ratio (OR) was 1.89 (1.28,2.80). However, there was no significant difference at 3-year and 5-year all-cause mortality between ABOi-DDLT and ABOc-DDLT groups. ABOi-DDLT group had a lower 1-year and 5-year death-censored graft survival than ABOc-DDLT, as the value of totally pooled OR was 1.91 (1.41,2.60) and 1.52 (1.12,2.05), respectively. No significant difference was detected at 3-year death-censored graft survival between ABOi-DDLT and ABOc-DDLT groups. ABOi-DDLT group had a higher complication incidence rate than ABOc-DDLT, and the value of totally pooled OR was 2.26 (1.53,3.33). We found no obvious bias except for the complication of living donor liver transplantation (LDLT; P = 0.038).

IN CONCLUSION

The short-term and long-term outcomes were worse after ABOi-DDLT than ABOc-DDLT in the all-cause mortality, death-censored graft survival, and complication incidence rate. However, the same outcomes were essentially comparable between ABOi-LDLT vs. ABOc-LDLT cohorts. Considering the current shortage of liver donors, we believe that ABOi-LT from living donor and deceased donors can save lives under emergency situations.

Is ABO-Incompatible Living Donor Liver Transplantation Really a Good Alternative for Pediatric Recipients?

BACKGROUND

ABO-incompatible (ABOi) living donor liver transplantation (LDLT) has been proposed to compensate for donor shortage. To date, few studies have reported detailed ABOi LDLT results in large series of pediatric patients. C4d complement deposition in graft capillaries has been reported to be associated with antibody-mediated rejection in solid organ transplantation.

METHODS

A retrospective case-control study was conducted, comparing clinical outcomes of each of 34 consecutive pediatric ABOi LDLT recipients with those of 2 non-ABOi pairs (n = 68), matched according to pre-transplant diagnostic criteria, age, and date of transplantation. In addition, we studied the C4d immunostaining pattern in 22 ABOi and in 36 non-ABOi recipients whose liver biopsy was performed within the first 4 post-transplant weeks for suspected acute rejection.

RESULTS

The incidence of biliary complications was higher in ABOi recipients (p < 0.05), as were the incidence of acute humoral rejection (p < 0.01) and the incidence of retransplantation (p < 0.05). All children who required retransplantation were older than 1 year at the time of ABOi LDLT. Positive C4d immunostaining was observed in 13/22 (59%) ABOi recipients versus 3/36 (8.3%) non-ABOi recipients (p < 0.0001).

CONCLUSIONS

ABOi LDLT is a feasible option for pediatric end-stage liver disease but carries increased risks for the recipient, especially for children older than 1 year, even with a specific preparation protocol. C4d immunostaining may be a hallmark of acute humoral rejection in ABOi liver transplantation.

Comparison of clinical outcomes between ABO-incompatible and ABO-compatible pediatric liver transplantation: a systematic literature review and meta-analysis

PURPOSE

ABO-incompatible (ABO-i) liver transplantation (LT) is a life-saving method for pediatric patients in emergency situations that has the potential to expand the pool of liver donors. However, the risks of ABO-i compared to ABO-compatible (ABO-c) LT are unclear. To address this clinical uncertainty, we conducted a systematic review and meta-analysis to compare clinical outcomes between ABO-i and ABO-c LT in pediatric patients.

METHODS

A systematic search for studies comparing outcomes between ABO-i and ABO-c LT was performed in the MEDLINE (PubMed), EMBASE, and Cochrane Library databases through May 2020. Outcomes evaluated included graft survival rate, patient survival rate, rejection, infection, biliary complications, and vascular complications. Quality of evidence was assessed using the Newcastle-Ottawa scale. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using RevMan 5.3.

RESULTS

A total of 12 studies involving 7461 patients were included in the review. Meta-analysis of these studies showed significantly lower 1 year, 3 year, and 5 year graft survival rates for ABO-i vs. ABO-c LT (1 year: OR = 0.46, 95% CI 0.35-0.59, P < 0.00001; 3 years: OR = 0.47, 95% CI 0.36-0.63, P < 0.00001; 5 year: OR = 0.48, 95% CI 0.37-0.63, P < 0.00001) as well as significantly lower 1 year, 3 year, 5 year, and 10 year patient survival rates for ABO-i vs. ABO-c (1 year: OR = 0.34, 95% CI 0.24-0.49, P < 0.00001; 3 years: OR = 0.24, 95% CI 0.14-0.40, P < 0.00001; 5 years: OR = 0.47, 95% CI 0.35-0.64, P < 0.00001; 10 years: OR = 0.59, 95% CI 0.38-0.90, P = 0.02). No significant differences were observed between the groups in incidence of cytomegalovirus infection, acute cellular rejection, acute rejection, biliary complications, or hepatic artery thrombosis.

CONCLUSIONS

Our systematic review and meta-analysis showed consistently lower patient survival and graft survival in pediatric ABO-i LT compared to ABO-c LT. However, ABO-i LT is still a life-saving emergency option for pediatric patients waiting for a suitable liver source.

Challenge to ABO blood type barrier in living donor liver transplantation

ABO incompatible living donor liver transplantation has the potential to expand the donor pool for patients with end stage liver diseases on the expense of challenges to overcome immunological barriers across blood type. There is a profound impact of age on incidence and severity of antibody mediated rejection (AMR). Even children older than 1 year have chances of AMR; children aged 8 years or older have risks of hepatic necrosis similar to adult liver recipients. The mechanism of AMR is based on circulatory disturbances secondary to inflammation and injury of the vascular endothelium caused by an antibody-antigen-complement reaction. The strategy to overcome ABO blood type barrier is based on both pre-transplant desensitization and adequate treatment of this phenomenon. Nowadays, rituximab is the standard means of desensitization but unfortunately an insufficient aid to treat AMR. Because of low incidence (less than 5% in the rituximab era), in practice of AMR only some case reports about the treatment of clinical AMR are available in the literature. Initial experiences revealed that the proteasome inhibitor, bortezomib might be a promising treatment based on its capacity to deplete plasma cell agents. Although ABO blood type barrier has been counteracted in 95% of patients by applying "rituximab-desensitization", many issues, such as prediction of high-risk patients of infection and AMR and secure treatment strategies for evoked AMR, remain to be resolved.

Outcomes after liver transplantation in accordance with ABO compatibility: A systematic review and meta-analysis

AIM

To evaluate the differences in outcomes between ABO-incompatible (ABO-I) liver transplantation (LT) and ABO-compatible (ABO-C) LT.

METHODS

A systematic review and meta-analysis were performed by searching eligible articles published before No-vember 28, 2016 on MEDLINE (PubMed), EMBASE, and Cochrane databases. The primary endpoints were graft survival, patient survival, and ABO-I-related complications.

RESULTS

Twenty-one retrospective observational studies with a total of 8247 patients were included in this meta-analysis. Pooled results of patient survival for ABO-I LT were comparable to those for ABO-C LT. However, ABO-I LT showed a poorer graft survival than ABO-C LT (1-year: OR = 0.66, 95%CI: 0.57-0.76, P < 0.001; 3-year: OR = 0.74, 95% CI 0.64-0.85, P < 0.001; 5-yearr: OR =0.75, 95%CI: 0.66-0.86, P < 0.001). Furthermore, ABO-I LT was associated with more incidences of antibody-mediated rejection (OR = 74.21, 95%CI: 16.32- 337.45, P < 0.001), chronic rejection (OR =2.28, 95%CI: 1.00-5.22, P = 0.05), cytomegalovirus infection (OR = 2.64, 95%CI: 1.63-4.29, P < 0.001), overall biliary complication (OR = 1.52, 95%CI: 1.01-2.28, P = 0.04), and hepatic artery complication (OR = 4.17, 95%CI: 2.26-7.67, P < 0.001) than ABO-C LT. In subgroup analyses, ABO-I LT and ABO-C LT showed a comparable graft survival in pediatric patients and those using rituximab, and ABO-I LT showed an increased acute cellular rejection in cases involving deceased donor grafts.

CONCLUSION

Although patient survival in ABO-I LT was comparable to that in ABO-C LT, ABO-I LT was inferior to ABO-C LT in graft survival and several complications. Graft survival of ABO-I LT could be comparable to that of ABO-C LT in pediatric patients and those using rituximab.

Case-matched comparison of ABO-incompatible and ABO-compatible living donor liver transplantation

BACKGROUND

ABO-incompatible (ABO-I) living donor liver transplantation (LDLT) has a high success rate. There are few detailed comparisons regarding biliary complications, infective complications and patient survival between ABO-compatible (ABO-C) and ABO-I LDLT. The aim was to compare the outcomes of ABO-I LDLT with those of ABO-C LDLT using the matched-pairs method.

METHODS

Patients who underwent ABO-I LDLT procedures between 2010 and 2013 were studied. They were matched for significant variables with patients who had ABO-C LDLT (1:2 matching).

RESULTS

Forty-seven ABO-I LDLT procedures were included. Ninety-four patients who had ABO-C LDLT were selected as a comparator group. The incidence of cytomegalovirus, bacterial and fungal infections during the first 3 months was similar after ABO-I LDLT and ABO-C LDLT (85 versus 76 per cent, 28 versus 37 per cent, and 13 versus 20 per cent, respectively). Antibody-mediated rejection occurred after two procedures within 2 weeks of transplantation, but liver function improved with plasma exchange in both patients. There were no differences in the rate of acute rejection and biliary complications between ABO-I and ABO-C groups (P = 0.478 and P = 0.511 respectively). Three patients who had ABO-I LDLT developed diffuse intrahepatic biliary complications and progressed to graft failure. The 1-, 2- and 3-year patient survival rates after ABO-I LDLT and ABO-C LDLT were 89 versus 87 per cent, 85 versus 83 per cent, and 85 versus 79 per cent, respectively.

CONCLUSION

The short-term outcomes of ABO-I LDLT were comparable to those of ABO-C LDLT in this study. ABO-I LDLT is an effective and safe transplant option with the potential to expand the pool of live donors.

The Role of Liver Sinusoidal Endothelial Cells in Induction of Carbohydrate Reactive B Cells Tolerance Through the Programmed Death 1/Programmed Death Ligand 1 Pathway

BACKGROUND

A spontaneous tolerance of B cells responding to blood group antigens frequently develops in ABO-incompatible pediatric liver transplantation (LT). Liver sinusoidal endothelial cells (LSECs), which exclusively express blood group antigens in the liver, possess a capacity to induce alloantigen-specific tolerance. In this study, we elucidated the role of LSECs in the tolerance induction of blood group antigen-reactive B cells after ABO-incompatible LT using mice that lack galactose-α(1,3)galactose (Gal) epitopes resembling blood group carbohydrate antigens.

METHODS

Using adoptive transfer of LSECs from wild type (WT) C57BL/6J mice to congenic α1,3-galactosyltransferase gene knockout (GalT) mice, we established orthotropic GalT → GalT LSEC chimera mice. Anti-Gal Ab (antibody) production was evaluated after immunization of GalT → GalT LSEC chimera mice with Gal rabbit RBC.

RESULTS

Adoptive transfer of LSECs isolated from WT GalT mice via the portal vein resulted in persistent engraftment of Gal LSECs in congenic GalT mouse livers. Only when GalT mice were splenectomized before LSEC inoculation, the GalT → GalT LSEC chimera lost the ability to produce anti-Gal Abs. The administration of blocking monoclonal Abs (mAbs) against programmed death ligand 1 to the splenectomized GalT → GalT LSEC chimera resulted in the recovery of anti-Gal Ab production.

CONCLUSIONS

These findings suggest that LSECs take a part in tolerization of immature but not mature B cells specifically for Gal. Furthermore, the programmed death 1/programmed death ligand 1 pathway likely plays a crucial role in the mechanisms underlying spontaneous tolerization of B cells responding to ABO-blood group antigens in LT.

ABO-incompatible pediatric liver transplantation in very small recipients: Birmingham's experience

Liver transplantation (LT) for very small recipients is challenging but in experienced centres, good results can be achieved. Despite the risk of antibody-mediated acute rejection, some studies have demonstrated the safety of ABO incompatible liver transplantation (ILT) in children and particularly in infants. The aim of our study was to describe the outcome of liver transplantation in infants <5 kg and the safety of using ILT in this group. All LT performed between 1991 and 2010 in children <5 kg were reviewed. Twenty-nine patients were included, five of whom had an ILT. Acute liver failure was encountered in 20 cases. The recipient age and weight at transplantation were respectively 63 days (range: 14-268 days) and 4 kg (range: 2.4-5 kg). The graft-to-recipient ratio was 6.1% (range 2.3-9%). An aortic conduit and delayed abdominal closure were used respectively in 76% and 81% of the procedures. The ABO compatible liver transplantation (CLT) and ILT groups were similar regarding recipient's demographics, graft types or technical transplantation data. The one- and five-yr patient and graft survival were respectively 62%, 62% and 62%, 57.9% with a median follow-up of 95 months. Vascular complications occurred in six cases (21.4%) and biliary complications were encountered in five patients (17%). Acute and chronic rejection developed respectively in 37% and 26% of the recipients. The five patients undergoing ILT are all alive without graft lost after a median follow-up of 34 months (range 7-55 months). When compared with the CLT group, no significant differences were found regarding patient or graft survival, vascular or biliary complications and rejection rates. In our experience, ILT in small infants has short and long term outcomes comparable to ABO-compatible grafts and excellent results can be achieved with a standard immunosuppressive protocol. To avoid mortality on the waiting list for neonatal recipients, ABO-incompatible liver grafts can be used safely.

Recipient outcomes after ABO-incompatible liver transplantation: a systematic review and meta-analysis

Background

ABO-incompatible live transplantation (ILT) is not occasionally performed due to a relative high risk of graft failure. Knowledge of both graft and patient survival rate after ILT is essential for donor selection and therapeutic strategy. We systematically reviewed studies containing outcomes after ILT compared to that after ABO-compatible liver transplantation (CLT).

Methodology/Principal Findings

We carried out a comprehensive search strategy on MEDLINE (1966–July 2010), EMBASE (1980–July 2010), Biosis Preview (1969–July 2010), Science Citation Index (1981–July 2010), Cochrane Database of Systematic Reviews (Cochrane Library, issue 7, 2010) and the National Institute of Health (July 2010). Two reviewers independently assessed the quality of each study and abstracted outcome data. Fourteen eligible studies were included which came from various medical centers all over the world. Meta-analysis results showed that no significantly statistical difference was found in pediatric graft survival rate, pediatric and adult patient survival rate between ILT and CLT group. In adult subgroup, the graft survival rate after ILT was significantly lower than that after CLT. The value of totally pooled OR was 0.64 (0.55, 0.74), 0.92 (0.62, 1.38) for graft survival rate and patient survival rate respectively. The whole complication incidence (including acute rejection and biliary complication) after ILT was higher than that after CLT, as the value of totally pooled OR was 3.02 (1.33, 6.85). Similarly, in acute rejection subgroup, the value of OR was 2.02 (1.01, 4.02). However, it was 4.08 (0.90, 18.51) in biliary complication subgroup.

Conclusions/Significance

In our view, pediatric ILT has not been a contraindication anymore due to a similar graft and patient survival rate between ILT and CLT group. Though adult graft survival rate is not so satisfactory, ILT is undoubtedly life-saving under exigent condition. Most studies included in our analysis are observational researches. Larger scale of researches and Randomized-Control Studies are still needed.

De novo cholangiocarcinoma after liver transplantation in a pediatric patient

To date, no child has been reported to develop de novo CCA after liver transplantation although patients with transplants have a significantly higher risk of malignancy than the general population. CCA is extremely rare in the pediatric age group, seen mostly in patients with a history of choledochal cysts, Caroli's disease, or PSC. We report the first case of pediatric de novo CCA in the liver allograft 12 yr after liver transplantation.

The persistent elimination of B cells responding to blood group A carbohydrates by synthetic group A carbohydrates and B-1 cell differentiation blockade: novel concept in preventing antibody-mediated rejection in ABO-incompatible transplantation

We demonstrated a novel strategy for specific and persistent inhibition of antibody (Ab) production against blood group A or B carbohydrate determinants necessary for successful ABO-incompatible transplantation. Similar to human blood group O or B individuals, mice have naturally occurring Abs against human blood group A carbohydrates in their sera. B cells with receptors for A carbohydrates in mice belonging to the CD5+CD11b+B-1a subset have phenotypic properties similar to those of human B cells. These cells could be temporarily eliminated by injecting synthetic A carbohydrates (GalNAcα1–3, Fucα1–2Gal) conjugated to bovine serum albumin (A-BSA) and anti-BSA Abs. In mice that received the injection of A-BSA/anti-BSA Abs, the serum levels of anti-A IgM were reduced, but immunization with human A erythrocytes resulted in increased serum levels of anti-A Abs. When combined with cyclosporin A (CsA) treatment, which blocks B-1a cell differentiation, and treatment with A-BSA/anti-BSA Abs, the serum levels of anti-A Abs were persistently undetectable in the mice even after the immunization. B cells with receptors for A carbohydrates were markedly reduced in these mice. These results are consistent with the hypotheses that treatment with A-BSA/anti-BSA Abs temporarily depletes B cells responding to A determinants, and CsA treatment prevents the replenishment of these cells.

Successful liver transplantation across the ABO incompatibility barrier in 6 cases of biliary atresia

BACKGROUND

The problem of ABO-incompatible liver transplantation still remains unsolved in older children. In this article, we report on our experience of 6 successful ABO-incompatible liver transplantations in patients with biliary atresia.

MATERIAL AND METHODS

Six patients (ABO incompatibility type A-->O:1 case, B-->O:2 cases, A-->B:3 cases) were enrolled in this study; 3 patients were aged approximately 1 year and the other 3 ranged in age from 9 to 24 years at the time of transplantation. Each patient received perioperative plasma exchange, until the anti-donor blood-type antibody titers became less than 1:16, and also systemic multidrug immunosuppressive therapy (cyclophosphamide, prednisolone, and tacrolimus). We applied the protocol of intraportal infusion therapy (local administration of prostaglandin E(1), steroid, and gabexate mesilate via a portal vein catheter), splenectomy, and rituximab administration for the older group.

RESULTS

Both the patient and graft survival rates remain at 100%, with the follow-up period of the patients ranging from 12 and 123 months. Acute cellular rejection occurred in 2 cases, and both were steroid sensitive. There was no incidence of humoral rejection. Although all cases developed viral infection, all recovered uneventfully with the administration of antiviral agents.

CONCLUSION

ABO-incompatible liver transplantation can be performed with a low risk of humoral rejection or late biliary complications using this combined antirejection strategy, even in older children.

Isotype-specific detection of ABO blood group antibodies using a novel flow cytometric method

Several methods to detect anti-A/B antibodies based on haemagglutination and haemolysis have been described. These methods measure predominantly anti-A/B immunoglobulin (Ig)M, whereas anti-A/B IgG and IgG subclasses are less well examined. We established a flow cytometry method (ABO-fluorescence-activated cell sorting; ABO-FACS) to quantify binding of anti-A/B IgM, IgG and IgG subclasses to human A or B red blood cells. Anti-A/B IgM were present in the majority of 120 blood donors, as expected from blood group typing. The sensitivity and specificity of anti-A/B IgM to predict the blood group was 93% and 96% respectively. Anti-A/B IgG was found in 34/38 blood group O samples (89%). Anti-B IgG in blood group A or anti-A IgG in blood group B was present in 4/28 (14%) and 1/28 (4%) samples, respectively, and absent in 26 AB sera. IgG2 was the predominant IgG subclass. The correlation of anti-A/B IgM and IgG in the ABO-FACS with haemagglutination titres was 0.870 and 0.783, respectively (n = 240; P < 0.001) whereas the comparison of ABO-FACS with ABO-enzyme-linked immunosorbent assay was less significant. In conclusion, ABO-FACS is a valid method to quantify anti-A/B IgM, IgG and IgG subclasses. It opens the possibility of isotype-specific monitoring of anti-A/B antibodies levels after ABO-incompatible solid organ and stem cell transplantation.

Characterization of the humoral immune response in two paediatric patients transplanted with split livers from ABO-incompatible living-related donors: appearance of cytomegalovirus-induced ABO antibodies

Two blood group O paediatric patients, 12 and 6 months old, were transplanted with liver segments from their blood group A2Le (a(-)b+) Se and blood group A1Le (a(-)b+) Se fathers, respectively. Recipient anti-A antibody titres were reduced prior to transplantation by blood exchange. Both patients had rejection episodes in the post-transplant period that were reversed by anti-rejection therapy. No anti-A antibody titre rise occurred concomitant with these rejections. Postoperatively both patients had cytomegalovirus (CMV) infections, and simultaneous with these infections, a strong increase in anti-A antibody titres was seen, but no rejection occurred. The anti-A antibody titre increase seemed to be specific for A antigens, because the anti-B and anti-alphaGal (anti-pig) antibody titres did not show any changes. CMV infection is a serious cause of morbidity and mortality in immunosuppressed patients, and the virus can influence glycosylation of infected cells. Whether this can explain the importance of the infection in relation to the increase in titre remains to be elucidated.

Studies of Pediatric Liver Transplantation: 2002 update. An overview of demographics, indications, timing, and immunosuppressive practices in pediatric liver transplantation in the United States and Canada

Studies of Pediatric Liver Transplantation (SPLIT) was initiated in 1995 for the purpose of collecting comprehensive data from children undergoing liver transplantation. As of May 31, 2002, 1761 children were registered in SPLIT from 38 participating centers in the United States and Canada. This report focuses on the demographics, primary diagnoses, clinical indications for transplant, and probability of obtaining liver transplantation for the 1187 children receiving a liver transplant after registration in SPLIT. Demographic information is also provided for the 1092 children who received their first ever liver transplantation. For this cohort, we also describe immunosuppressive practices at the time of transplant, and how the use of different medications changes with time.

Impact of recipient age on outcome of ABO-incompatible living-donor liver transplantation

BACKGROUND

Transplantation of hepatic grafts from ABO-incompatible donors is controversial because of the risk of hyperacute rejection mediated by preformed anti-ABO antibodies. The aim of the present study was to evaluate the outcome of liver transplants performed with ABO-incompatible living-donor livers and to detect risk factors for development of complications.

METHODS

From June 1990 to February 2000, 66 patients, 10 months to 55 years old (median, 2 years old), received 68 ABO-incompatible living-donor liver grafts. The antibody titer and clinical course were followed prospectively during a period ranging from 3 to 11 years.

RESULTS

The 5-year patient survival was 59%, 76%, and 80% for ABO-incompatible, ABO-compatible, and ABO-identical grafts, respectively (P<0.01). In patients <1 year old, > or =1 to <8, > or =8 to <16, and and > or =16 years old, 5-year survival was 76%, 68%, 53%, and 22%, respectively. The incidence of intrahepatic biliary complications and hepatic necrosis in ABO-incompatible living-related grafts (18% and 8%, respectively) was significantly (P<0.0001) greater than in ABO-compatible and ABO-identical grafts (both 0.6% and 0%, respectively). Predictive risk factors for increased mortality and morbidity were age greater than 1 year and elevated anti-ABO titers before transplantation.

CONCLUSIONS

ABO-incompatible liver transplantation was carried out with relative safety in infants <1 year old but was not satisfactory in children >1 year in long-term follow-up. Patients aged >8 years remain at considerable risk of early fatal outcome because of hepatic necrosis, and new strategies to prevent antibody-mediated rejection are required.

Periportal edema and necrosis as diagnostic histological features of early humoral rejection in ABO-incompatible liver transplantation

Humoral rejection caused by antidonor blood group A/B antibodies is one of the most important obstacles for successful ABO-incompatible liver transplantation. However, no specific morphologic features of liver biopsies to distinguish humoral rejection from other conditions such as ischemia or sepsis have been satisfactorily documented. To histologically clarify the early changes in humoral rejection, we studied 41 cases of living donor ABO-incompatible liver transplantation whose allograft biopsies during the first episode of suspected acute rejection were available within the first postoperative month. Postoperative isohemagglutinin IgM titers were x64 or more in 21 patients (51%; high-titer group) and less than x64 in 20 cases (49%; low-titer group). In the high-titer group, elevation of postoperative titers x64 or more occurred within postoperative days 5.7 +/- 4.1 (range: 1-17). An increase in the incidence of cholangitis was observed in the high-titer group (90% vs. 30%, P <.0001), as well as poorer overall graft survival than in the low-titer group (38% vs. 70%, P <.05). Seven biopsies obtained from the high-titer group within 3 days after the onset of elevation of the antibody titers and one biopsy obtained at the peak of the antibody titers demonstrated periportal edema and necrosis, neither of which was found in the low-titer group. All grafts of these patients caused massive hepatocyte necrosis or severe biliary complications. In conclusion, a high morbidity rate of ABO-incompatible liver transplantation is associated with high postoperative levels of antibody titers. Periportal edema and necrosis observed during elevation of antibody titers can be regarded as histological indications of early changes in severe humoral rejection.

Living donor liver transplantation with special reference to ABO-incompatible grafts and small-for-size grafts

Living donor liver transplantation (LDLT) has developed on the basis of increased safety of conventional liver surgery and the need for expanding donor sources, especially in children. Indications for LDLT were soon extended to adult patients in Japan, where cadaveric donation was limited. The right liver is now routinely transplanted to adults to avoid small-for-size graft syndrome, even though the right liver graft has the disadvantages of less remaining donor liver and the question of donor safety. Assessing the suitable size or quality of the graft, as well as of the remnant donor liver, is one of the most important problems in adult LDLT. Although several tactics have been proposed to manage the small-for-size syndrome, their efficacy remains a question. We suggest that small-for-size syndrome is preventable by engaging in careful donor selection or using effective agents for hepatic microcirculatory disturbance control. Sometimes for LDLT only ABO-incompatible grafts are available from relatives, but they must be transplanted despite the expected poor outcome in adults and older children. To overcome the problems in this situation, we developed a novel protocol including intraportal infusion therapy with methylprednisolone, prostaglandin E1, and gabexate mesylate. Two adult patients undergoing ABO-incompatible LDLT have now survived 53 and 35 months after transplantation with good liver function. However, the other two patients suffered thrombotic microangiopathy postoperatively and died owing to cerebral hemorrhage or multiple organ failure, respectively. Further investigation is needed to improve the outcome of liver transplantation across the ABO blood group barrier.

Specialized transfusion support for solid organ transplantation

As solid organ transplantation becomes increasingly common and complex, the demands on the transfusion service expand. Transplant recipients present unique challenges not only because of product availability but also because of specialized blood components, serologic problems, and immunologic effects of transfusion on the allograft and the recipient. Solid organ transplant recipients receive immunosuppressive agents that make them more susceptible to infectious or immunologic complications of transfusion such as cytomegalovirus infection and graft-versus-host disease. Other immunologic consequences of transfusion such as alloimmunization may also be severe, resulting in acute or chronic graft rejection. The transfusion specialist must recommend the optimal approach to reducing the risk of these complications in organ transplant recipients.

A large, single center investigation of the immunogenetic factors affecting liver transplantation

BACKGROUND

Reports on the relevance of immunogenetic factors in liver transplantation are often conflicting or inconclusive. We have, therefore, investigated a range of factors that may underlie liver graft survival.

METHODS

The influences of HLA, flow cytometric, and enhanced cytotoxic crossmatching and immunoglobulin (Ig)A levels on graft survival, and acute and chronic rejection were investigated for a single center involving 446 patients over 13 years.

RESULTS

The effect of HLA mismatching on graft survival was significant (P<10(-2)) and was reversed in recipients with autoimmune diseases (P<0.5x10(-2)), whereas the effect of HLA mismatches on the level of acute rejection was detrimental in all recipients. There was a significant effect of a positive cytotoxic crossmatch on 3-month (P<10(-5)) and 1-year (P<10(-4)) graft survival, and an additional effect of the flow cytometric crossmatch was seen for chronic rejection (P<10(-2)) and acute rejection (P<10(-2)). Recipients with HLA-A1,B8,DRB1*0301 had higher levels of acute rejection (P<0.5x10(-2)), and recipients who received an ABO compatible-nonidentical transplant have a significantly higher risk (P<10(-2)) of developing chronic rejection. Finally, the beneficial effect of high serum IgA and, specifically, IgA anti Fab, seen in renal transplants was not evident in liver transplants, and in fact the opposite may be true, at least for acute rejection (P<0.5x10(-2)).

CONCLUSIONS

By separating the recipients with autoimmune disease from other patients and by including acute and chronic rejection as outcome parameters, we have used the power of a large single-centre study to delineate the significance of some of the important immunogenetic factors involved in liver transplantation.

Does the donor-recipient ABO blood group compatibility status predict subsequent lung transplantation outcomes?

BACKGROUND

The study was conducted to compare lung transplantation outcomes between ABO-identical (AI) and ABO-compatible (AC) recipients.

METHODS

Charts of lung allograft recipients transplanted between February, 1990 and October, 1995 were reviewed. Standard triple-drug immunosuppression and general antimicrobial prophylaxis were provided. Surveillance spirometry was administered every three months. Flexible bronchoscopy (FB) with transbronchial biopsies (TBBs) were undertaken for clinical indications. Time to event analysis on acute (AR) and chronic (CR) rejection and actuarial survival were determined by Kaplan-Meier analysis. Cumulative curves were compared with a log rank test. Comparisons of age, maximum forced expiratory volume in one second (FEV1) in the single (SLT) and double (DLT) lung recipients, duration of intensive care unit and hospital stay were carried out using the Wilcoxon Rank Sum test. Gender, race, underlying diagnoses, cytomegalovirus (CMV) status and pulmonary reimplantation response (PRR) were compared by Chi-square or Fisher's exact test where appropriate.

RESULTS

Of the 100 lung recipients (age = 42.5 +/- 13.4 years; M:F = 50:50), 64 were AI and 36 AC. Median follow-up was 22 (range = 0-78) months. Outcome did not differ significantly between the 2 groups in terms of intensive care unit and hospital stay, PRR incidence and grade, incidence and frequencies of AR, median time and grade of first AR, maximum FEV1 for SLT and DLT recipients, incidence of CR and survival at 12 months.

CONCLUSIONS

As the donor supply remains limited, this could considerably simplify the logistics of future transplantation.

Hepatic artery thrombosis in living related liver transplantation

BACKGROUND

Hepatic artery thrombosis (HAT) after orthotopic liver transplantation remains a significant cause of graft loss in pediatric patients. We previously reported that the microsurgical techniques for arterial anastomosis can reduce the incidence of HAT in living related liver transplantation (LRLT). The purpose of this study is to analyze the risk factors for HAT after LRLT. A total of 245 patients received 250 liver transplants.

METHODS

Eight arteries in eight patients, reconstructed with the use of loupe magnification (HAT; 1/8, 12.5%), were excluded from this study. We observed HAT in 4 patients of the 242 transplants (1.7%, HAT group). Seventeen factors were compared between the HAT and the control group (those without HAT).

RESULTS

HAT occurred in 3 of 33 grafts (9%) from ABO-incompatible donors, whereas it occurred in 1 of 209 grafts (0.5%) from identical or compatible donors (P=0.008). The corrected volume of fresh-frozen plasma intraoperatively transfused in the HAT group (46.9+/-30.3 ml/kg) was significantly (P=0.015) different from that in the control group (10.2+/-1.9 ml/mg). In all four patients with HAT, emergent revisions of the anastomosis were performed. Two patients with ABO-incompatible grafts died of hepatic failure and sepsis.

CONCLUSIONS

Although microsurgical techniques can minimize the surgical risk factors for HAT, overtransfusion of fresh-frozen plasma in high-risk patients (ABO incompatible) may be a critical factor in the development of HAT in LRLT.

Current status and outcome of pediatric liver transplantation

In this article the diagnostic indications for hepatic transplantation are addressed in detail. The outcome of liver transplantation is also examined, including the impact of the following factors on survival: age and weight at transplantation, type of liver disease, and size of liver allograft, including living related transplantation. Morbidity and quality of life after transplantation are other aspects reviewed in this chapter.

Factors affecting survival after orthotopic liver transplantation in infants

The technical and medical management of small infants requiring orthotopic liver transplantation remains a challenge. The present study examined 117 orthotopic liver transplantations performed in 101 infants from <1 to 23 months of age between March 1988 and February 1995 to determine factors that influence patient and graft outcome. Factors analyzed included etiology of liver disease, recipient and donor age and weight, United Network for Organ Sharing (UNOS) status, retransplantation, ABO-compatibility, full-size (FS) versus reduced-size grafts, vascular thrombosis (VT), including hepatic artery and portal vein (PVT), and the presence of lymphoproliferative disease (LPD). UNOS status 1, fulminant hepatic failure, and the development of Epstein-Barr virus-associated LPD were each associated with 10-20% lower patient and graft survival rates. Of 101 infants, 11 (11%) developed LPD with an associated 36% mortality. VT occurred in 10 (9 hepatic artery and 1 portal vein) of 117 orthotopic liver transplantations (9%), all less than 1 year of age, and was associated with significantly poorer 1-year (50% vs. 85% no VT, P<0.01) and 5-year patient survival rates (50% vs. 83% no VT, P<0.01). One-year graft survival rates for FS grafts in recipients <12 months versus 12-23 months were 67% vs. 94% (P<0.01); the patient survival rate was also significantly lower in FS graft recipients <12 months (76% vs. 100%, P<0.05). Recipients <5 months of age had the worst survival rates: 1-year and 5-year patient survival rates were 65% and 46% for recipients 0-4 months (n=17) versus 82% and 82% for recipients 5-11 months (n=56), and 93% and 93% for recipients age 12-23 months (n=28; P<0.05). In summary, factors associated with reduced survival rates include recipient age <5 months, recipient age <12 months who received FS grafts, development of VT and donor weight <6 kg. There was a trend for UNOS status 1, fulminant hepatic failure, and presence of LPD to be associated with reduced survival rates.