Influence of human leukocyte antigen matching on liver allograft survival and rejection: "the dualistic effect"

Global research hotspots and trends of acute rejection after liver transplantation from 1988 to 2022: a bibliometric analysis

Background: Acute rejection (AR) is the predominant form of rejection observed in liver transplantation and plays a crucial role in transplant immunology. This study aims to utilize bibliometric analysis to understand the status quo, hotspots, and future trends of research on AR after liver transplantation. Methods: We searched the Web of Science Core Collection (WoSCC) for studies on AR after liver transplantation published from 1988 to 2022. The Bibliometric Online Analysis Platform, VOSviewer, and CiteSpace were used for analysis of all extracted publications. Results: This study included 2,398 articles published in 456 journals by 12,568 authors from 1,965 institutions in 55 countries/regions. The United States and its affiliated institution, the University of Pittsburgh, were the most productive contributors. Transplantation (n = 12,435) was the most frequently cited journal. Neuhaus P (n = 38) was the highest output author, and Demetris AJ (n = 670) was the most co-cited author. The research hotspots of AR after liver transplantation include pathogenesis, immunosuppressive therapy, and prognosis. Emerging research directions include regulatory T cells, immunosuppression minimization, intra-patient variability (IPV) of tacrolimus, and novel non-invasive diagnostic markers. Conclusion: Our study utilized bibliometric methods to analyze the study of AR after liver transplantation over the past 35 years. With the prolonged survival of liver transplant recipients, the most active areas currently focus on individualized treatment and improving patient prognosis. Minimizing adverse reactions to immunosuppressive therapy while simultaneously avoiding an increase in the risk of AR remains a future research focus.

The effect of donor against recipient one-way HLA mismatch on liver transplantation outcomes from a multicenter registry analysis

Donor against recipient one-way Human leukocyte antigen (HLA) mismatch (D → R one-way HLA MM) seemed strongly associated with graft-versus-host disease (GVHD). The aim of this study is to investigate the relevance of D → R one-way HLA MM in outcome of liver transplantation (LT). We retrospectively analyzed 2670 patients in Korean Organ Transplantation Registry database between April 2014 and December 2020. The patients were categorized into two groups whether D → R one-way HLA MM or not and evaluated the outcomes of LT between the two groups. 18 patients were found to be D → R one-way HLA MM. The incidence of GVHD (0.3% vs. 22.2%, p < 0.001) and mortality rate (11.6% vs. 38.9%, p = 0.003) was much higher in D → R one-way HLA MM group. D → R one-way HLA MM at 3 loci was seemed to be strongly associated with the incidence of GVHD (OR 163.3, p < 0.001), and found to be the strongest risk factor for patient death (HR 12.75, p < 0.001). Patients with D → R one-way HLA MM at 3 loci showed significantly lower overall survival (p < 0.001) but there were no significant differences in rejection-free survival and death-censored graft survival. D → R one-way HLA MM at 3 loci not only affects the overall survival of LT patients but also the incidence of GVHD.

The Effect of Genetic HLA Matching on Liver Transplantation Outcome: A Systematic Review and Meta-Analysis

Objective

We aim to investigate the effects of genetically based HLA matching on patient and graft survival, and acute and chronic rejection after liver transplantation.

Background

Liver transplantation is a common treatment for patients with end-stage liver disease. In contrast to most other solid organ transplantations, there is no conclusive evidence supporting human leukocyte antigen (HLA) matching for liver transplantations. With emerging alternatives such as transplantation of bankable (stem) cells, HLA matching becomes feasible, which may decrease the need for immunosuppressive therapy and improve transplantation outcomes.

Methods

We systematically searched the PubMed, Embase, and Cochrane databases and performed a meta-analysis investigating the effect of genetic HLA matching on liver transplantation outcomes (acute/chronic rejection, graft failure, and mortality).

Results

We included 14 studies with 2682 patients. HLA-C mismatching significantly increased the risk of acute rejection (full mismatching: risk ratio = 1.90, 95% confidence interval = 1.08 to 3.33, P = 0.03; partial mismatching: risk ratio = 1.33, 95% confidence interval = 1.07 to 1.66, P = 0.01). We did not discern any significant effect of HLA mismatching per locus on acute rejection for HLA-A, -B, -DR, and -DQ, nor on chronic rejection, graft failure, or mortality for HLA-DR, and -DQ.

Conclusions

We found evidence that genetic HLA-C matching reduces the risk of acute rejection after liver transplantation while matching for other loci does not reduce the risk of acute rejection, chronic rejection, graft failure, or mortality.

Donor-recipient human leukocyte antigen A mismatching is associated with hepatic artery thrombosis, sepsis, graft loss, and reduced survival after liver transplant

Human leukocyte antigen (HLA) matching is not routinely performed for liver transplantation as there is no consistent evidence of benefit; however, the impact of HLA mismatching remains uncertain. We explored the effect of class I and II HLA mismatching on graft failure and mortality. A total of 1042 liver transplants performed at a single center between 1999 and 2016 with available HLA typing data were included. The median follow-up period was 9.38 years (interquartile range 4.9-14) and 350/1042 (33.6%) transplants resulted in graft loss and 280/1042 (26.9%) in death. Graft loss and mortality were not associated with the overall number of mismatches at HLA-A, HLA-B, HLA-C, HLA-DR, and HLA-DQ loci. However, graft failure and mortality were both increased in HLA mismatching on graft failure and mortality the presence of one (p = 0.004 and p = 0.01, respectively) and two (p = 0.01 and p = 0.04, respectively) HLA-A mismatches. Elevated hazard ratios for graft failure and death were observed with HLA-A mismatches in univariate and multivariate Cox proportional hazard models. Excess graft loss with HLA-A mismatch (138/940 [14.7%] mismatched compared with 6/102 [5.9%] matched transplants) occurred within the first year following transplantation (odds ratio 2.75; p = 0.02). Strikingly, transplants performed at a single all grafts lost due to hepatic artery thrombosis were in HLA-A-mismatched transplants (31/940 vs. 0/102), as were those lost due to sepsis (35/940 vs. 0/102). In conclusion, HLA-A mismatching was associated with increased graft loss and mortality. The poorer outcome for the HLA-mismatched group was due to hepatic artery thrombosis and sepsis, and these complications occurred exclusively with HLA-A-mismatched transplants. These data suggest that HLA-A mismatching is important for outcomes following liver transplant. Therefore, knowledge of HLA-A matching status may potentially allow for enhanced surveillance, clinical interventions in high-risk transplants or stratified HLA-A matching in high-risk recipients.

Donor with HLA-C2 is associated with acute rejection following liver transplantation in southern Chinese

Apart from presenting peptides to T cells, class I HLA molecules serve as ligands for KIRs and regulate the response of NK cells. The role played by HLA and KIR in the acute rejection (AR) following liver transplantation has been controversial. In this retrospective study, we assessed the influence of class I HLA alleles, HLA matching between donor-recipient pairs, recipient KIR and donor HLA ligands on AR following liver transplantation in southern Chinese. 143 recipients and 78 donors obtained from a single transplant center were included in the study cohort. 33 recipients with histologically confirmed AR were observed. We found that the incidence of AR did not correlate with donor or recipient class I HLA alleles and HLA matching. Neither recipient KIR gene nor the KIR genotype was associated with AR, moreover, high-resolution genotyping of 14 functional KIR genes of recipients showed that no KIR allele was independently associated with AR. However, the frequency of HLA-C2⁺ donor significantly increased in AR group compared with NAR group (52.9% vs. 24.6%, P = 0.03). In the presence of HLA-C2 by the donor allograft, AR was more frequently observed in recipients with normal expressed KIR2DS4 (43.8% vs. 15.0%, P = 0.03). Donor with HLA-C2 is therefore a major determinant of AR, which can confer risk effect in liver transplantation. Our findings can provide valuable clues for better understanding pathogenesis of AR and have important clinical implications in liver transplantation for Chinese. This article is protected by copyright. All rights reserved.

Do Recipients of Genetically Related Donors Have Better Outcomes After Living Donor Liver Transplantation?

BACKGROUND

There are few data on genetic relation of the donor and outcomes in living donor liver transplantation (LDLT) recipients. We compared outcomes of LDLT between recipients of genetically related and unrelated donors in a large single-center series.

METHODS

The study included 1372 adult, ABO-compatible, primary LDLT recipients, who received a graft from either a first-degree relative (parent, sibling, son, or daughter; n = 756) or unrelated donor (spouse or relative of the spouse; n = 616).

RESULTS

The mean age of the recipients with a related donor was 50.2 ± 10.8 years compared with 47.3 ± 9.3 years for recipients with unrelated donors (P = 0.000). Chronic rejection was significantly more common in the genetically unrelated donor group than in the genetically related donor group (28 [4.5%] versus 9 [1.1%]; P = 0.000) at a mean follow-up of 37 months (15-95 months). There were no significant differences in other outcomes between the 2 groups. The 12-month and 36-month survival between the unrelated and related groups was 87.6% versus 90%, and 86.3% versus 89.7% respectively (P = 0.115). The multivariate analysis revealed genetically unrelated donors (odds ratio [OR]: 3.88, 95% confidence interval [CI]: 1.80-8.34, P = 0.001) and history of acute cellular rejection (OR: 3.39, 95% CI: 1.68-6.81, P = 0.001) as predictors of chronic rejection.

CONCLUSION

Although chronic rejection was found to be more common in genetically unrelated donors, the patient survival after LDLT was similar.

The impact of human leukocyte antigen donor and recipient serotyping and matching on liver transplant graft failure in primary sclerosing cholangitis, autoimmune hepatitis, and primary biliary cholangitis

Human leukocyte antigen (HLA) serotyping is not considered to have significant impact on liver graft survival and does not factor into U.S. organ allocation. Immune-related liver diseases such as primary sclerosing cholangitis (PSC), autoimmune hepatitis (AIH), and primary biliary cholangitis (PBC) have been speculated to represent a disease subgroup that may have significantly different graft outcomes depending on HLA donor/recipient characterization. The aim of this study was to investigate whether HLA serotyping/matching influenced post-transplant graft failure for immune-related liver diseases using the United Network for Organ Sharing database. From 1994 to 2015, 5665 patients underwent first-time liver-only transplants for PSC, AIH, and PBC with complete graft survival and donor/recipient HLA data. Graft failure was noted in 38.6% (2188/5665), and all groups had comparable 5-year graft survival (75.1%-78.8%, P = 0.069). The overall degree of, and loci-specific mismatch level, did not influence outcomes. Multivariable Cox proportional hazards regression noted increased graft failure risk for recipient HLA-B7, HLA-B57, HLA-B75, HLA-DR13 and donor HLA-B55, HLA-B58, and HLA-DR8 for PSC patients, protective effects for recipient HLA-DR1 and HLA-DR3 for AIH patients, and increased risk for HLA-DR7 for AIH patients. These findings warrant further investigation to evaluate the impact of HLA serotyping on post-transplant outcomes.

Living Donor Liver Transplantation in a Highly Allo-Sensitized Recipient: Confusing Influence of Rituximab on the Lymphocytotoxicity Crossmatch Test. A Case Report

Objective: We report a successful living donor liver transplantation (LDLT) from donor (husband) to highly allo-sensitized recipient (wife) against donor-adopting sufficient preoperative preparation. Methods: A 47-year-old woman with primary biliary cirrhosis was referred to our hospital as a potential candidate of LDLT. Her husband was willing to donate his hemiliver. As the lymphocytotoxicity crossmatch (LCT-XM) test based on a complement-dependent cytotoxicity and flow panel reactive antibody (PRA) test revealed that the patient had strong donor-specific anti-HLA antibody, the patient received rituximab twice for preoperative desensitization. A total of 5 rounds of plasmapheresis were also performed. Results: Nevertheless, the LCT-XM test 9 days after the administration of rituximab did not turn to negative while flow PRA test was almost negative. Suspecting that residual rituximab in the recipient's serum might interfere with the LCT-XM test because of its potential ability to activate the complement, we retried the test after absorbing rituximab from the serum with immunomagnetic bead. Conclusion: The result: The LCT-XM test turned to negative, suggesting that the desensitization therapy was adequate. A left liver graft was transplanted as planned, and the postoperative course was uneventful. The patient is doing well 12 months after transplantation.

Human leukocyte antigen matching in heart transplantation: systematic review and meta-analysis

Allocation of donors with regard to human leukocyte antigen (HLA) is controversial in heart transplantation. This paper is a systematic review and meta-analysis of the available evidence. PubMed, Embase, and the Cochrane Library were searched systematically for studies that addressed the effects of HLA matching on outcome after heart transplantation. Fifty-seven studies met the eligibility criteria. 34 studies had graft rejection as outcome, with 26 of the studies reporting a significant reduction in graft rejection with increasing degree of HLA matching. Thirteen of 18 articles that reported on graft failure found that it decreased significantly with increasing HLA match. Two multicenter studies and nine single-center studies provided sufficient data to provide summary estimates at 12 months. Pooled comparisons showed that graft survival increased with fewer HLA-DR mismatches [0-1 vs. 2 mismatches: risk ratio (RR) = 1.09 (95% confidence interval (CI): 1.01-1.19; P = 0.04)]. Having fewer HLA-DR mismatches (0-1 vs. 2) reduced the incidence of acute rejection [(RR = 0.81 (0.66-0.99; P = 0.04)]. Despite the considerable heterogeneity between studies, the short observation time, and older data, HLA matching improves graft survival in heart transplantation. Prospective HLA-DR matching is clinically feasible and should be considered as a major selection criterion.

Human herpesvirus-6 and cytomegalovirus DNA in liver donor biopsies and their correlation with HLA matches and acute cellular rejection

Herpesvirus reactivation is common after liver transplantation.

Objective

Analyze the presence of cytomegalovirus (HCMV) and human herpesvirus-6 (HHV-6) DNA in liver donor biopsies, seeking to better understand issues involving human donor leukocyte antigens (HLA)-A, B and DR, as well as correlations with acute cellular rejection.

Methods

Fifty-nine liver transplantation patients were investigated for the presence of HCMV and HHV-6 DNA in liver donor biopsies, using the Nested-PCR technique. The clinical donor information and HLA matches were obtained from the São Paulo State Transplant System. The recipients’ records regarding acute cellular rejection were studied.

Results

Seven (11.8%) biopsies were positive for HCMV DNA and 29 (49%) were positive for HHV-6 DNA. In 14 donors with HLA-DR 15 nine had HHV-6 DNA positive liver biopsy with a tendency for significant association (p = 0.09), 22 recipients developed acute cellular rejection and 9/22 were positive for HLA-DR 15 (p = 0.03; χ² = 4.51), which was statistically significant in univariate analysis and showed a tendency after multivariate analysis (p = 0.08).

Conclusion

HHV-6 DNA was prevalent in liver donors studied as well as HLA-DR 15. These findings suggest that patients with HLA-DR 15 in liver donor biopsies develop more rejection after liver transplantation.

Relevance of HLA compatibility in living donor liver transplantation: the double-edged sword associated with the patient outcome

HLA compatibility in living donor liver transplantation (LDLT) seems relevant to the acceptability of graft livers because LDLT recipients often share most or some part of HLAs with the respective donors. This study retrospectively investigated whether HLA compatibility affected the outcome of LDLT. Three hundred ninety LDLTs were performed in this hospital, and 346 pairs of HLAs (HLA-A, B, DR) were retrieved from the medical record between October 1996 and March 2011. The dates of the deaths were censored when a recipient apparently died of or was retransplanted by other causes than graft failure because of host-versus-graft (HVG) response to purely analyze the outcomes of LDLT in view of HVG response. The relationship between HLA compatibility and graft-versus-host disease (GVHD) was also analyzed. No recipients with recipient-against-donor HLA mismatch (R→D MM) 0 experienced graft failure by HVG response. On the other hand, three of five recipients with "R→D MM 0" together with "donor-against-recipient MM 3" died of fatal GVHD. HLA compatibility in LDLT not only affected the long-term acceptance of graft livers but also the risk of fatal GVHD.

Does a positive lymphocyte cross-match contraindicate living-donor liver transplantation?

BACKGROUND

There is still no consensus on the importance of lymphocyte cross-matching (LCM) in the field of living-donor liver transplantation (LDLT).

METHODS

LCM examinations are routinely performed before LDLT, and the results of complement-dependent cytotoxicity were used in this study. A total of 1157 LDLT cases were evaluated. The recipients were divided into four groups based on the LCM and ABO compatibilities: (1) negative LCM and identical/compatible ABO; (2) negative LCM and incompatible ABO; (3) positive LCM and identical/compatible ABO; and (4) positive LCM and incompatible ABO. The diagnosis of antibody-mediated rejection (AMR) was made based on the clinical course, immunological assays and histopathological findings. C4d immunostaining was added if AMR was suspected.

RESULTS

The LCM-positive LDLT recipients showed significantly poorer outcomes than the LCM-negative recipients. Among the LCM-positive recipients, 44.1% of recipients eventually died and 85.2% of recipients revealed positive C4d findings. The survival rate of LCM-positive and ABO-incompatible group was 0.50. The survival days were compared with the LCM-negative and ABO-identical/compatible group, and the LCM-positive and ABO-identical/compatible group clearly showed early death after LDLT, although the ABO-incompatible groups did not show significant. The factors of age, disease, pre-transplant scores, LCM, ABO compatibility and graft-recipient weight ratio showed statistical significance in multivariate analysis for important factors of LDLT outcomes. However, the LCM and ABO compatibilities had no synergetic effects on the LDLT survival.

CONCLUSION

HLA antigens are more widely expressed than ABO antigens, and advanced immunological strategies must be established for LCM-positive LDLT as well as for ABO-incompatible LDLT.

Killer cell immunoglobulin-like receptor genotype and killer cell immunoglobulin-like receptor-human leukocyte antigen C ligand compatibility affect the severity of hepatitis C virus recurrence after liver transplantation

In 20% to 30% of infected individuals, hepatitis C virus (HCV) can cause cirrhosis and hepatocellular carcinoma, for which liver transplantation is the best treatment available. HCV re-infection is universal, and hepatitis disease recurrence occurs in most cases with a 30% probability of progression to graft cirrhosis at 5 years post-transplant. The immunological response to HCV involves natural killer (NK) cells and killer cell immunoglobulin-like receptors (KIRs), which specifically recognize human leukocyte antigen (HLA) class I antigens present on target cells. The effector functions of NK cells are influenced by inhibitory KIR interaction with self-HLA class I ligands, with HLA-C being the most predominant. This study examines the roles of KIR genotypes and their HLA ligands in both HCV disease recurrence and its progression. A total of 151 patients were included in the cohort, and their clinical details were recorded. Liver biopsies were used to define the absence/presence of recurrent hepatitis, the degree of fibrosis, and the progression to cirrhosis over a 10-year period. Mismatching of KIR-HLA-C ligands between donor-recipient pairs was associated with the recurrence of hepatitis (P = 0.008). The presence of KIR2DL3 in the recipient correlated with progression to liver fibrosis (P = 0.04). The mismatching of HLA-KIR ligands favored the progression of the recurrent hepatitis to fibrosis only in the presence of KIR2DL3 (P = 0.04). These preliminary results indicate that the KIR genotype and KIR-HLA-C ligand compatibility play roles in the recurrence and progression of hepatitis C disease in liver transplant recipients.

Long-term outcome of human leukocyte antigen mismatching in liver transplantation: results of the National Institute of Diabetes and Digestive and Kidney Diseases Liver Transplantation Database

A perfect or nearly perfect human leukocyte antigen (HLA) match has been associated with better immediate and long-term survival of diseased donor kidney transplants. However, the effect of HLA matching for hepatic allografts remains poorly defined. Using data from the National Institutes of Diabetes and Digestive and Kidney Diseases Liver Transplantation Database, we investigated the association between HLA mismatches and hepatic allograft survival, disease recurrence, and immunosuppression interactions. A, B, and DR loci were used to calculate total mismatch scores of 0 (no mismatches in any loci) to 6 (mismatches in all loci). Seven hundred ninety-nine adults (male, 55%; female, 45%) underwent 883 liver transplants. The 10-year graft survival according to total mismatch score was as follows: 0-2, 60%; 3-4, 54%; and 5-6, 57%. There was a negative effect of mismatching at the A locus on patient survival, with shorter survival for patients with 1 or 2 mismatches compared with 0 mismatches [P = 0.05, hazard ratio (HR) = 1.6]. Patients on tacrolimus with 1 or 2 mismatches at B or DR loci appeared to have increased rates of patient and graft survival compared to patients with 0 mismatches, with the appearance of a protective effect of tacrolimus (HR = 0.67). The effect of HLA mismatching was more pronounced on certain disease recurrences. DR-locus mismatch increased recurrence of autoimmune hepatitis (P = 0.01, HR = 4.2) and primary biliary cirrhosis (P = 0.04, HR = 2). Mismatch in the A locus was associated with more recurrence of hepatitis C virus (P = 0.01, HR = 1.6) and primary sclerosing cholangitis (P = 0.03, HR = 2.9).

CONCLUSION

Mismatching at the A locus decreases patient survival in liver transplant recipients, and mismatching at the DR and A loci affects recurrence of autoimmune liver diseases and hepatitis C, respectively.

Liver retransplantation in children: a SPLIT database analysis of outcome and predictive factors for survival

To examine outcomes and identify prognostic factors affecting survival after pediatric liver transplantation, data from 246 children who underwent a second liver transplantation (rLT) between 1996 and 2004 were analyzed from the SPLIT registry, a multi-center database currently comprised of 45 North American pediatric liver transplant programs. The main causes for loss of primary graft necessitating rLT were primary nonfunction, vascular complications, chronic rejection and biliary complications. Three-month, 1- and 2-year patient survival rates were inferior after rLT (74%, 67% and 65%) compared with primary LT (92%, 88% and 85%, respectively). Multivariate analysis of pretransplant variables revealed donor age less than 1 year, use of a technical variant allograft and INR at time of rLT as independent predictive factors for survival after rLT. Survival of patients who underwent early rLT (ErLT, <30 days after LT) was poorer than those who received rLT >30 days after LT (late rLT, LrLT): 3-month, 1- and 2-year patient survival rates 66%, 59%, and 56% versus 80%, 74% and 61%, respectively, log-rank p = 0.0141. Liver retransplantation in children is associated with decreased survival compared with primary LT, particularly, in the clinical settings of those patients requiring ErLT.

Human leukocyte antigen and adult living-donor liver transplantation outcomes: an analysis of the organ procurement and transplantation network database

Human leukocyte antigen (HLA) compatibility has no clinically significant impact in cadaveric liver transplantation. Less is known regarding living-donor liver transplantation (LDLT). Our prior analysis of the Organ Procurement and Transplantation Network (OPTN) database suggested a higher graft failure rate in patients who underwent LDLT from donors with close HLA match. We further investigated the effect of HLA-A, -B, and -DR matching on 5-yr graft survival in adult LDLT by analyzing OPTN data regarding adult LDLT performed between 1998 and 2005. We evaluated associations between 5-yr graft survival and total, locus-specific, and haplotype match levels. Separate analyses were conducted for recipients with autoimmune (fulminant autoimmune hepatitis, cirrhosis secondary to autoimmune hepatitis, primary biliary cirrhosis, primary sclerosing cholangitis) or nonautoimmune liver disease. Multivariable Cox proportional hazard models were used to evaluate interactions and adjust for potential confounders. Among 631 patients with available donor/recipient HLA data, the degree of HLA match had no significant effect on 5-yr graft survival, even when analyzed separately in recipients with autoimmune vs. nonautoimmune liver disease. To be able to include all 1,838 adult LDLTs, we considered a first-degree related donor as substitute for a close HLA match. We found no difference in graft survival in related vs. unrelated pairs. In conclusion, our results show no detrimental impact of close HLA matching on graft survival in adult LDLT, including in recipients with underlying autoimmune liver disease.

BK Virus Nephropathy in Pediatric Renal Transplant Recipients: An Analysis of the North American Pediatric Renal Trials and Collaborative Studies (NAPRTCS) Registry

BACKGROUND AND OBJECTIVES

There is limited information regarding BK virus nephropathy in pediatric kidney transplantation. The objective of this study was to evaluate cases of BK virus nephropathy in the North American Pediatric Renal Trials and Collaborative Studies database.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Using a questionnaire that was sent to North American Pediatric Renal Trials and Collaborative Studies centers, we assessed the incidence, risk factors, clinical features, and outcomes of BK virus nephropathy in pediatric renal transplant recipients who received a transplant between 2000 and 2004.

RESULTS

BK virus nephropathy was reported in 25 (4.6%) of 542 patients at a median onset of 10.1 mo after transplantation. The median age was 11 yr. All patients who were tested reported BK viruria, and 19 (91%) of 21 who had plasma tested reported BK viremia. Treatment of BK virus nephropathy included reduction of immunosuppression (84%), cidofovir (24%), leflunomide (8%), and intravenous Ig (20%). Simultaneous rejection treatment was reported in four (16%). The median creatinine was 2.0 mg/dl at a mean follow-up of 24 mo. There were six (24%) graft failures in the patients with BK virus nephropathy at a mean of 24 mo after diagnosis. Rejection occurred in eight (32%) after diagnosis. Multivariate analysis showed that use of polyclonal induction therapy and zero HLA DR mismatch were associated with the development of BK virus nephropathy.

CONCLUSIONS

This first multicenter, retrospective, cohort study of BK virus nephropathy in pediatric renal transplant recipients found a BK virus nephropathy incidence of 4.6% and identified polyclonal induction and zero HLA DR mismatch as significant risk factors for BK virus nephropathy.

Impact of recipient HLA-C in liver transplant: a protective effect of HLA-Cw*07 on acute rejection

The involvement of the human leukocyte antigen (HLA) in liver graft acceptance is controversial, but the frequency of acute rejection (AR) remains high in spite of the use of the modern immunosuppressive agents. The present study was aimed at determining whether an association exists between liver recipient HLA-C polymorphism and AR development that could influence graft acceptance. Four hundred and forty-six liver recipients and 473 controls were studied within the framework of a collaborative study carried out by the Spanish Transplant Immunotolerance Group (RED-GIT). HLA-A and -B were typed by the standard microlymphocytotoxicity technique, and HLA-C by polymerase chain reaction-sequence-specific oligonucleotide probes (PCR-SSOP). A statistically significant decrease in the HLA-Cw*07 allele frequency was found in liver recipients suffering AR episodes compared to those without AR (NAR). Studies regarding the possible influence of the Asn80 and Lys80 epitopes showed that the Asn80 epitope also could be associated with AR. However, further analysis considering Asn80 alleles others than HLA-Cw*07, confirmed that the apparent protective effect of the Asn80 epitope was actually from the HLA-Cw*07 allele. In conclusion, the HLA-Cw*07 allele carried by the liver recipient is negatively associated with AR development, and could be considered a predictive factor for liver graft acceptance.

The effect of HLA class I (A and B) and class II (DR) compatibility on liver transplantation outcomes: an analysis of the OPTN database

The purpose of this study was to explore the relationship between human leukocyte antigen (HLA) compatibility and liver transplantation outcomes by analyzing the effect of HLA compatibility on 5-year graft survival. We analyzed first liver transplants between 1987 and 2002 in the Organ Procurement and Transplantation Network (OPTN) database, where A, B, or DR loci data were available. Graft failure was defined as retransplantation or death from transplant-related cause. We evaluated associations between total and locus-specific match levels and 5-year graft survival. Multivariable Cox proportional-hazard models were used to evaluate statistical interactions and adjust for the effect of potential confounders. Among 29,675 first-time transplants, the overall degree of HLA match had no effect on 5-year graft survival, even after controlling for potential confounders. Univariate and multivariable analyses showed that the 0 HLA antigen mismatch cohort of patients had higher 5-year graft failure rates than the other 6 antigen mismatch groups. However, this occurred in a small group with a disproportionately large number of live donors and split-liver recipients. When these recipients were excluded from the analysis, the effect was no longer seen. Finally, multivariable, locus-specific analyses showed no association between 5-year graft survival and degree of match/mismatch and the A, B, or DR loci. In conclusion, this careful examination of the OPTN database, with respect to HLA match or mismatch and liver graft survival, reaffirms that HLA matching has no clinically significant impact on this outcome.

Impact of HLA-C and Bw epitopes disparity on liver transplantation outcome

The occurrence of graft rejection episodes after orthotopic liver transplantation (OLT) despite the use of immunosuppressive drugs designed to suppress T lymphocyte functions, indicates the involvement of other types of cells in this process. The activity of natural killer cells and their killer immunoglobulin-like receptors (KIR) is regulated by human leukocyte antigen (HLA) class I determinants; C and Bw epitopes. Because recipient/donor pairs are usually HLA mismatched, recipient natural killer alloreactivity may be the mediating factor in rejection. In this retrospective study, we have analyzed rejection occurrence and outcome in 66 OLT recipients, 42 with and 24 without C or Bw epitope disparity in the rejection direction. Recipients transplanted from donors with no C epitope disparity had significantly fewer rejection episodes in the first year after transplantation compared with recipients transplanted across C epitope disparity (p = 0.0002). Moreover, this effect was more pronounced when the outcome was analyzed in OLT recipients across negative crossmatching for the anti-HLA class I and II antibodies. In contrast, Bw epitope disparity did not affect the outcome. In conclusion, C epitopes disparity between recipients and donors in the rejection direction appears to influence posttransplant liver outcome. This finding may be helpful in the choice of appropriate liver donor and planning immune suppression.

HLA-DRB1 donor-recipient mismatch affects the outcome of hepatitis C disease recurrence after liver transplantation

BACKGROUND & AIMS

This study extends our previously reported observations that various immunological factors are associated with the occurrence of histologically proven recurrent hepatitis C. The two specific issues investigated were to confirm the associations of MHC alleles and donor/recipient mismatch with the occurrence of recurrent hepatitis C in an independent cohort of newly transplanted patients and to look for immunologic and nonimmunologic variables affecting the severity of the recurrent disease.

METHODS

Two separate cohorts of consecutive patients were studied: a look-back cohort (LC) of 120 patients and a cohort for studying the disease progression (CSDP) of 190 patients. Protocol liver biopsies were obtained at least 1, 3, 5, 7, and 10 years after liver transplantation (LT).

RESULTS

A fully mismatched donor/recipient pair at the DRB1 locus was confirmed to be associated with both the recurrence of histologic hepatitis in the LC (59% vs 23%, P = .0002) and its progression beyond stage 3 in the CSPD (71.4% vs 39.3%, P = .0003). Relevant immunologic and nonimmunologic variables were included into a multivariate Cox proportional model and three variables, namely, donor age, full HLA-DRB1 donor-recipient mismatch, and HLA B14, resulted in independent risk factors for the development of severe fibrosis.

CONCLUSION

This study provides evidence that DRB1 donor-recipient mismatch affects both the occurrence and progression of recurrent hepatitis C disease. This information is clinically relevant as it may help to better allocate organs and to recognize patients at risk for progression so that specific interventions can be implemented.

Development of donor-specific microchimerism in liver transplant recipient with HLA-DRB1 and -DQB1 mismatch related to rejection episodes

Migration of donor-derived cells to recipient tissues after liver transplantation has been suggested as a mechanism to induce and maintain allograft tolerance, although important issues remain including acute rejection posttransplantation mortality, and complications related to immunosuppressive therapy. We therefore examined the relation of rejection to chimerism based upon recipient and donor mismatch of HLA-DRB1 and -DQB1 alleles. Laboratory analysis of peripheral blood was performed before and 10 days to 16 months after liver transplantation in 32 recipients, using ganglion or spleen cell samples of respective donors. DNA was extracted for HLA-DRB1 and DQB1 allele typing using polymerase chain reactions with sequence-specific primers (PCR-SSP). Microchimerism was analyzed through nested PCR. Our results confirmed that patients with one or two mismatched HLA-DRB1 and-DQB1 alleles showed microchimerism and no rejection (P <.05). Microchimerism was present in 71.88% of the patients, and a significant association of rejection P <.05 was found when microchimerism was correlated to graft rejection. These results suggest that the presence of microchimerism may be associated with acceptance, tolerance and survival of the allograft.

Impact of HLA-C on acute rejection in liver transplantation

Although liver transplants show a special tolerogenic behaviour, rejection remains an important problem that involves several immunological mechanisms, some of which are unknown. Our study sought to analyze the influence of HLA-C polymorphism on short-term liver graft acceptance by HLA-C genotyping of 100 orthotopic liver transplant recipient-donor pairs. Recipients were statified according to the occurrence of acute rejection. HLA-Cw*06 allele appeared to be underrepresented among recipients without versus those with acute rejection or those in control groups. With regard to HLA-C allelic compatibility, the frequency of acute rejection or those in episodes decreased with fewer HLA-C mismatches. These findings suggest the participation of HLA-C molecules in liver graft alloresponses, involving HLA-C genotyping, as well as compatibility.

Intrathymic inoculation of donor liver specific antigen alleviates rejection of liver allotransplantation

Use and effects of liver specific antigen in orthotopic liver transplantations were researched in this study. Group I: syngeneic control (Wistar-to-Wistar); Group II: acute rejection (SD-to-Wistar); Group III: Thymic inoculation of SD rat LSA day 7 before transplantation. The observation of common situation and survival time, rejection grades, NF-KappaB activity of splenocytes and IL-2mRNA expression of grafted liver were used to analyze acute rejection severity and immune state of animals in different groups. The common situation of group I was very well after transplantation and no signs of rejection were found. Recipients of group II lost body weight progressively. All dead within day 9 to day 13 posttransplantation; median survival time was 10.7+/-0.51 days. It was an optimal acute rejection control. As for group III, 5 out of 6 recipients survived for a long time and common situation was remarkably better than that of group II. Its rejection grades were significantly lower than that of group II(P < 0.05). NF-KappaB activity was only detected in group I at day 5 and day 7 after transplantation, whereas high activity of NF-KappaB was detected at all time points in group II and the low NF-KappaB activity detected in group III was significantly lower than that of group II(P < 0.05). No IL-2mRNA expression was detected at any time point in group I, whereas high level expression was detected at all time points in group II and the low level expression only detected at day 3 in group III was significantly lower than that of group II(P < 0.05).

CONCLUSION

LSA is an important transplantation antigen which is involved directly in the immunorejection of liver transplantation. We report here for the first time that intrathymic inoculation of LSA can alleviate the rejection of liver allotransplantation; and that grafts can survive for a long time thereby, thus leading to a novel way to achieve liver transplantation immunotolerance.

Expression of CD80 on Kupffer cells is enhanced in cadaveric liver transplants

In experimental animals inhibition of T cell co-stimulation immediately after organ transplantation effectively prevents rejection. We investigated whether the expression of co-stimulatory molecules is enhanced in cadaveric liver transplants, whether their expression is influenced by the transplantation procedure, and whether variation in expression between liver transplants is related to the occurrence of acute rejection. Expression of CD80, CD86 and the macrophage marker CD68 were determined by immunohistochemistry in biopsies from 40 clinical liver transplants obtained at different time-points during the transplantation procedure, and in normal liver tissue obtained from 10 human livers. Expression of CD80 and CD86 on Kupffer cells was graded by comparison with CD68-staining. In a subgroup CD80 and CD86 mRNA was quantified by real-time detection polymerase chain reaction. CD86 was expressed in all liver transplants and normal livers on the majority of Kupffer cells. CD80 was absent or sporadically expressed in normal liver tissue, but in 18 of 40 liver transplants at least one-quarter of Kupffer cells expressed CD80. CD80- and CD86-mRNA and protein expression in liver transplants did not change during the warm ischaemic and reperfusion phases of the transplantation procedure. CD80-expression on Kupffer cells varied strongly between individual donor livers; this variation was, however, not significantly related to the occurrence of acute rejection after transplantation. In conclusion, in nearly half of cold-preserved cadaveric liver transplants an increased proportion of Kupffer cells express CD80 at the time of transplantation in comparison with normal liver tissue. The expression was not further induced by warm ischaemia and reperfusion. However, the observed variation in CD80-expression between liver transplants is not a accurate predictive measure for acute rejection.

Immunotolerance of liver allotransplantation induced by intrathymic inoculation of donor soluble liver specific antigen

AIM: To study the effects of liver specific antigen (LSA) on the immunoreaction of liver allotransplantation and its significance.

METHODS: Orthotopic liver transplantation was used in this study. Group I: syngeneic control (Wistar-to-Wistar); Group II: acute rejection (SD-to-Wistar). Group III: acute rejection treated by intramuscular injection of cyclosporine A (CsA) (SD-to-Wistar + CsA). Group IV: Intrathymic inoculation of SD rat LSA one week before transplantation (LSA + SD-to-Wistar). The common situation and survival time, rejection grades, NF-κB activity of splenocytes and intragraft cytokine gene expression were observed to analyze the acute rejection severity and immune state of animals.

RESULTS: The common situation of Wistar-to-Wistar group was very good after the transplantation and no signs of rejection were found. Recipients of SD-to-Wistar group lost body weight progressively. All died within 9 to 13 d after transplantation with the median survival time of 10.7 ± 0.51 d. It was an optimal control for acute rejection. The common situation of SD-to-Wistar + CsA group was bad during CsA medication but only with mild rejection. As for LSA + SD-to-Wistar group, 5 of 6 recipients survived for a long time and common situation was remarkably better than that of SD-to-Wistar group and SD-to-Wistar + CsA group. Its rejection grades were significantly lower than that of SD-to-Wistar group (P = 0.026). Furthermore, no significant discrepancies of rejection were found between SD-to-Wistar group and LSA + SD-to-Wistar group at day 7 and day 12 (P = 0.067). NF-κB activity, IFN-γ and IL-2mRNA expression were significantly inhibited in LSA + SD-to-Wistar group compared with that of SD-to-Wistar group (P < 0.05).

CONCLUSION: LSA is an important transplantation antigen which involves in the immunorejection of liver transplantation directly. We reported for the first time that intrathymic inoculation of LSA can induce immnotolerance of liver allotransplantation and grafts can survive for a long time thereby, thus leading to a novel way to liver transplantation immunotolerance.

Human leukocyte antigen-C in short- and long-term liver graft acceptance

In liver transplantation, rejection is still an important problem, and the role of human leukocyte antigens (HLA) has not been clearly established. At present, the possible involvement of HLA-C antigen in liver transplantation is still unexplored. The aim of this work was to analyze the influence of HLA-C polymorphism on the outcome of liver transplantation. For this purpose, genotyping of 100 orthotopic liver transplant recipient-donor pairs for HLA-C was performed with polymerase chain reaction-sequence-specific primers (PCR-SSPs). Liver recipients were stratified according to the occurrence of acute rejection. Patients without acute rejection were found to have a lower frequency of the HLA-Cw*06 allele compared with those with acute rejection or the control group. Moreover, when the role of HLA-C dimorphism was analyzed, natural killer (NK)1-alloantigens were found to be predominant in recipients without acute rejection. When the match of HLA-C single alleles and NK-alloantigens between donor and recipient was analyzed, it appeared that the frequency of acute rejection gradually decreased with decrease of the number of allele mismatches. Graft survival was increased when the number of mismatches in both HLA-C or NK-alloantigens was lower. In conclusion, the HLA-C locus may play a role in liver graft alloreactivity or allotolerance and, therefore, may be useful to avoid acute rejection and to achieve graft acceptance, resulting in a better final outcome in liver transplantation.

Role of HLA compatibility in pediatric living-related liver transplantation

BACKGROUND

Human leukocyte antigen (HLA) matching is, at present, not used for the allocation of cadaveric hepatic allografts because the liver is generally believed to be less susceptible to HLA-mediated rejection. However, the exact role of HLA compatibility in the long-term outcome of liver transplantation is not yet clearly defined. One of the advantages of living-related liver transplantation (LRLT) could be a better histocompatibility between donor and recipient. This study aimed at an assessment of the influence of HLA compatibility in a large series of LRLTs.

METHODS

A total of 321 pediatric patients who underwent ABO-identical or ABO-compatible primary LRLT from the parental donors in the period between June 1990 and August 2000 were involved in the study. Graft survival, rejection episodes, and immunosuppression were evaluated from the viewpoint of HLA compatibility.

RESULTS

The overall 1- and 5-year graft survivals were 85.7% and 84.1%, respectively. The cumulative 5-year graft survivals in HLA 0-, 1-, 2- and 3-mismatch groups (A, B, and DR) were 100% (n=10), 78.9% (n=19), 86.2% (n=87), and 82.9% (n=205), respectively (P=0.525). The overall incidence of rejection during the follow-up period (median 66 months, range 16-139 months) was 46.1%. No significant difference was found in the incidence of rejection and rejection-free survival among the four groups. However, steroid-resistant rejection that necessitated OKT3 treatment (n=6) and chronic rejection (n=2) were recognized only in the 3-mismatch group. The whole-blood trough level of tacrolimus and the duration of steroid administration were not significantly different among the groups. The rate of the patients who succeeded in withdrawal from immunosuppression was also similar among the groups. However, the trough level of tacrolimus needed for maintenance of an acceptable liver function test during the chronic phase tended to be lower in well-matched pairs, and a high percentage of immunosuppressant-free patients were found in the 0-mismatch group. Fatal graft-versus-host disease developed in one patient with a complete one-way HLA-matched transplant.

CONCLUSION

We could not find any supportive evidence of beneficial effects of HLA-matching in pediatric LRLT. The potential benefit of HLA-matching for the reduction protocol for immunosuppressants may play a role in the withdrawal program. It appears unnecessary to pay attention to HLA compatibility in donor selection in LRLT, except for one-way HLA matching, or to adjust immunosuppression according to HLA compatibility.

Polymorphisms in immunoregulatory genes: towards individualized immunosuppressive therapy?

In organ transplantation, successful immunosuppression requires that both rejection and infection episodes be minimized. Unfortunately it is currently impossible to predict individual dose requirement for immunosuppressive drugs, but a number of studies of various immune response genes are now being performed with a view to identifying genotypes associated with rejection and/or infection. The key role of cytokines in the immune response and other processes, including fibrosis, has concentrated most of this attention on polymorphisms in cytokine genes. Data on polymorphisms in genes encoding tumor necrosis factor-alpha, transforming growth factor-beta, interferon-gamma and interleukin (IL)-1, 4, 6 and 10 together with the IL-4 receptor have been analyzed but so far there is currently no indication of any consistently positive associations between graft rejection and any of these polymorphisms. Studies of other immunomodulatory genes including the CTLA4 gene and the chemokine receptor CCR-5 have proved more positive though the data, so far, are only preliminary. In conclusion, additional large series studies of these and other cytokine genes, as well as other immunoregulatory gene polymorphisms of proven functional significance are needed to achieve major progress in this area.

Acute cellular rejection in liver transplant recipients under cyclosporine immunosuppression: predictive factors of response to antirejection therapy

BACKGROUND

Predictive factors of response to antirejection therapy in acute cellular rejection (ACR) in liver transplantation are not well established.

METHODS

To investigate the possible existence of these factors, we reviewed 111 consecutive episodes of ACR fulfilling the following criteria: histologically confirmed ACR; cyclosporine-based immunosuppression; initial antirejection treatment with high-dose steroid boluses; minimum follow-up of 2 weeks after treatment; and no other graft complication interfering with evaluation of therapeutic response. ACR episodes not responding to initial steroid therapy were given additional treatment (OKT3 and/or repeated steroid boluses). We analyzed the association of the response to the antirejection treatment with different clinical, laboratory, histological, and donor-recipient compatibility variables at two times: after the initial antirejection therapy, and after all the antirejection therapy administered.

RESULTS

Eighty episodes of ACR (72%) resolved after the initial therapy with high-dose steroid boluses, and another 18 (16%), initially steroid-resistant, resolved with additional antirejection treatment. Thirteen episodes (12%) were refractory to all antirejection treatment administered. Variables with independent predictive value of nonresponse to initial therapy with steroid boluses were late-onset ACR (>2 months after transplantation), high serum bilirubin and alanine aminotransferase, low blood cyclosporine concentration in the week before antirejection treatment, and severe histological endothelialitis. Late-onset ACR and high serum bilirubin were also independent predictors of refractoriness to all the treatment administered.

CONCLUSIONS

Response to antirejection treatment in ACR in liver transplantation can be predicted by several clinical and laboratory data. ACR episodes with factors predictive of therapeutic unresponsiveness could benefit from more aggressive antirejection treatment.

In vitro cytokine production of TNFalpha and IL-13 correlates with acute liver transplant rejection

Individuals may differ in their capacity to produce cytokines. Since cytokines play a key role in allograft rejection, we investigated whether inter-individual differences in cytokine production by in vitro stimulated PBMC are related to the occurrence of acute liver transplant rejection. Our study group comprised 49 liver transplant recipients and 30 healthy individuals. Rejection, which occurred within one month after liver transplantation, was defined in 22 patients ("rejectors") as biopsy-proven rejection, treated with high dose prednisolone. Patients who never experienced rejection episodes were termed as "nonrejectors" (n=27). PBMC of healthy individuals and of liver transplant recipients, collected late after transplantation (mean 3.5 years), were cultured in the presence and absence of Concanavalin A. The production of TNF-alpha, IFN-gamma, IL-10, and IL-13 was measured in supernatant after 1, 2, 3, 4, and 7 days of cell culture. In cell culture, stimulated PBMC of rejectors were found to produce significantly higher levels of TNF-alpha, while there was a trend towards higher production of IFN-gamma and IL-10 as compared to nonrejectors. After grouping patients into high or low cytokine producers based upon reference levels of the healthy individuals using multivariate analysis it was found that occurrence of acute liver transplant rejection correlated to high production of TNF-alpha and low production of IL-13. After stimulated cell culture PBMC of liver transplant recipients show a differential production of TNF-alpha and IL-13 which is correlated with the occurrence of acute liver transplant rejection.

Weaning of immunosuppression in living donor liver transplant recipients

BACKGROUND

Some reported studies have indicated the possibility of immunosuppression withdrawal in cadaveric liver transplantation. The aim of this study was to evaluate the possibility and feasibility of weaning living donor liver transplant recipients from immunosuppression.

METHODS

From June of 1990 to October of 1999, 63 patients were considered to be weaned from immunosuppression. They consisted of 26 electively weaned patients and 37 either forcibly or incidentally weaned patients (nonelective weaning) due to various causes but mainly due to infection. Regarding elective weaning, we gradually reduced the frequency of tacrolimus administration for patients who survived more than 2 years after transplantation, maintained a good graft function, and had no rejection episodes in the preceding 12 months. The frequency of administration was reduced from the conventional b.i.d. until the start of weaning to q.d., 4 times a week, 3 times a week, twice a week, once a week, twice a month, once a month, and finally, the patients were completely weaned off with each weaning period lasting from 3 to 6 months. The reduction method of nonelective weaning depended on the clinical course of each individual case. When the patients were clinically diagnosed to develop rejection during weaning, then such patients were treated by a reintroduction of tacrolimus or an additional steroid bolus when indicated.

RESULTS

Twenty-four patients (38.1%) achieved a complete withdrawal of tacrolimus with a median drug-free period of 23.5 months (range, 3-69 months). Twenty-three patients (36.5%) are still being weaned at various stages. Sixteen patients (25.4%) encountered rejection while weaning at median period of 9.5 months (range, 1-63 months) from the start of weaning. All 16 were easily treated with the reintroduction of tacrolimus or additional steroid bolus therapy.

CONCLUSIONS

We were able to achieve a complete withdrawal of immunosuppression in some selected patients. Although the mechanism of graft acceptance in these patients has yet to be elucidated, we believe that a majority of long-term patients undergoing living donor liver transplantation may, thus, be potential candidates to be successfully weaned from immunosuppression.

Alloreactivity of natural killer cells in allogeneic liver transplantation

BACKGROUND

The cytolytic attack of natural killer (NK) cells is blocked by recognition of the idiotypic phenotype of certain polymorphisms in HLA class I molecules, specifically by HLA-C alleles (Asn77, Lys80 or Ser77, Asn80) or HLA-Bw4 allotypes. Because liver allograft rejection is associated closer with mismatch in HLA class I than class II, we investigated the role of NK cells in acute hepatic allograft rejection in vivo/in vitro.

METHODS

The HLA pattern was typed with serological and polymerase chain reaction (PCR) techniques. In 31 liver transplantations, mononuclear cells from donor spleen and peripheral blood of recipients (before/after transplantation) were cultured in mixed lymphocyte cultures (MLC). MLC-derived effector cells were analyzed by flow cytometry and tested in 51Cr-release assays.

RESULTS

Patients with NK allospecific constellations tended to have higher numbers of NK cells in peripheral blood during the first 4 weeks after transplantation, and patients' lymphocytes stimulated with donor cells had a significantly higher cytotoxic activity on days 14 and 21 compared with patients without NK allospecificity. However, acute rejection occurred with similar frequency in both groups (31% with allospecific constellations vs. 40% without). Moreover, acute rejection episodes were not associated with an increase in NK cells in vivo or enhanced cytotoxicity of NK cells to donor target cells.

CONCLUSIONS

Under standard immunosuppressive therapy, NK allospecific constellations did not seem play a major role in acute hepatic allograft rejection. Strategies to prevent or treat NK allospecific constellations after liver transplantation are not likely to reduce the incidence or severity of acute allograft rejection.

Role of cytokine gene polymorphisms in acute rejection and renal impairment after liver transplantation

Although immunosuppressive regimens are effective, rejection occurs in up to 50% of patients after orthotopic liver transplantation (OLT), and there is concern about side effects from long-term therapy. Knowledge of clinical and immunogenetic variables may allow tailoring of immunosuppressive therapy to patients according to their potential risks. We studied the association between transforming growth factor-beta, interleukin-10, and tumor necrosis factor alpha (TNF-alpha) gene polymorphisms and graft rejection and renal impairment in 121 white liver transplant recipients. Clinical variables were collected retrospectively, and creatinine clearance was estimated using the formula of Cockcroft and Gault. Biallelic polymorphisms were detected using polymerase chain reaction-based methods. Thirty-seven of 121 patients (30.6%) developed at least 1 episode of rejection. Multivariate analysis showed that Child-Pugh score (P =.001), immune-mediated liver disease (P =.018), normal pre-OLT creatinine clearance (P =.037), and fewer HLA class 1 mismatches (P =.038) were independently associated with rejection. Renal impairment occurred in 80% of patients and was moderate or severe in 39%. Clinical variables independently associated with renal impairment were female sex (P =.001), pre-OLT renal dysfunction (P =.0001), and a diagnosis of viral hepatitis (P =.0008). There was a significant difference in the frequency of TNF-alpha-308 alleles among the primary liver diseases. After adjustment for potential confounders and a Bonferroni correction, the association between the TNF-alpha-308 polymorphism and graft rejection approached significance (P =.06). Recipient cytokine genotypes do not have a major independent role in graft rejection or renal impairment after OLT. Additional studies of immunogenetic factors require analysis of large numbers of patients with appropriate phenotypic information to avoid population stratification, which may lead to inappropriate conclusions.

Analysis of alloreactivity and intragraft cytokine profiles in living donor liver transplant recipients with graft acceptance

Although some previous studies have indicated the possibility of immunosuppression withdrawal in clinical liver transplantation, the mechanism of graft acceptance is not clear. The aim of this study is to elucidate the alloreactivity against the donor and intragraft cytokine profiles in living donor liver transplant (LDLT) recipients with graft acceptance. In October 1999, we had 23 patients who survived without immunosuppression after LDLT with a median drug-free period of 25 months (range: 3-69 months). They consisted of six patients who were electively weaned by an elective weaning protocol and 17 either forcibly or accidentally weaned patients due to various causes but mainly due to infection. We evaluated the alloreactivity against the donor in these patients by a mixed lymphocyte reaction and intragraft cytokine profiles by real-time reverse transcriptase-polymerase chain reaction. The development of donor-specific hyporeactivity was observed in the patients with graft acceptance. The cytokine pattern in the supernatant of the culture medium revealed a down regulation of T helper (Th) 1 cytokine INF gamma against the donor while no significant difference was seen in Th2 cytokine IL-10. Regarding the intragraft cytokine profiles, we could find no amplification of Thl cytokines (IL-2, INF y) and IL-4 while some of the patients revealed a gene expression of IL-10 with no significant difference from that of the normal, untransplanted liver specimen. In addition, no difference was observed in any other cytokines (IL-1beta, IL-8, IL-15, TNFalpha) compared with those of the normal controls. We propose that the down regulation of Th1 cytokine is one possible mechanism of graft acceptance in LDLT recipients.

Acute rejection of hepatic allografts from HLA-DR13 (Allele DRB1(*)1301)-positive donors

Acute rejection of hepatic allografts does not show consistent association with the number of mismatches of HLA classes I and II. Therefore, we investigated the relation between specific donor or recipient HLA antigens and the occurrence of acute rejection. HLA typing of 35 liver transplant recipients and donors was performed by serological standard technique, with confirmation and subtyping by polymerase chain reaction with sequence-specific primers. HLA class I antigens were not associated with the occurrence of acute rejection. The graft was positive for HLA-DR13 in 8 of 13 transplant recipients (62%) with acute rejection, but only 4 of 22 recipients (18%; P =.024; P(Bonferroni-corrected) =.33, not significant) without rejection. The graft was positive for DRB1*1301 in 7 of 13 recipients (54%) with acute rejection, but only 1 of 22 recipients (5%) without rejection (P =.002; P(Bonferroni-corrected )=.028). This patient had experienced long-lasting bacterial sepsis, which markedly reduced the risk for acute rejection. We speculate that the expression of donor DRB1*1301 (if mismatched) may increase the risk for acute hepatic allograft rejection.

Chronic liver allograft rejection in a population treated primarily with tacrolimus as baseline immunosuppression: long-term follow-up and evaluation of features for histopathological staging

BACKGROUND

Predisposing factors, long-term occurrence, and histopathological changes associated with recovery or progression to allograft failure from chronic rejection (CR) were studied in adult patients treated primarily with tacrolimus.

METHODS

CR cases were identified using stringent criteria applied to a retrospective review of computerized clinicopathological data and slides.

RESULTS

After 1973 days median follow-up, 35 (3.3%) of 1049 primary liver allograft recipients first developed CR between 16 and 2532 (median 242) days. The most significant risk factors for CR were the number (P<0.001) and histological severity (P<0.005) of acute rejection episodes and donor age >40 years (P<0.03). Other demographic and matching parameters were not associated with CR in this cohort. Ten patients died with, but not of, CR. Eight required retransplantation because of CR at a median of 268 days. Ten resolved either histologically or by normalization of liver injury tests over a median of 548 days. CR persisted for 340 to 2116 days in the remaining seven patients. More extensive bile duct loss (P<0.01), smallarterial loss (P<0.03), foam cell clusters (P<0.01) and higher total bilirubin (P<0.02) and aspartate aminotransferase (P<0.03) were associated with allograft failure from CR.

CONCLUSIONS

Early chronic liver allograft rejection is potentially reversible and a combination of histological, clinical, and laboratory data can be used to stage CR. Unique immunological and regenerative properties of liver allografts, which lead to a low incidence and reversibility of early CR, can provide insights into transplantation biology.

Influence of immunogenetic background on the outcome of recurrent hepatitis C after liver transplantation

In immunocompetent patients, specific human leukocyte antigen (HLA) class II alleles have been associated with the severity of hepatitis C virus (HCV)-related disease, in particular, HLA-DRB1*11 has been found to exert a protective effect. The authors have analyzed the role of HLA class I and II alleles in determining the frequency, timing, and progression of histologically proven recurrent hepatitis C in 89 patients who underwent a liver transplant for HCV-related cirrhosis. In addition, the influence of HLA mismatch between donor and recipient, HCV genotype, and use of steroid pulses was also evaluated. Median patient follow up was 35 months (range 4-119). HLA-DRB1 typing was performed by genomic analysis in all cases. Liver biopsies were obtained routinely and at least at yearly intervals. Histologically proven recurrent hepatitis was observed in 46 patients (52%), 10 patients progressing to stage 5-6 fibrosis in most cases within 2 years after transplant. By univariate analysis, 3 variables, HLA-B14, HLA-DRB1*04, and HLA-DRB1 donor/recipient mismatch, showed a significant effect on time to recurrent hepatitis C disease. These parameters were included in a multivariate regression model along with HCV genotype, treatment with steroid pulses and DRB1*11. HLA-B14, HLA-DRB1*04, and HLA-DRB1 donor/recipient mismatch were confirmed to provide a significant and independent contribution to the risk of hepatitic disease recurrence. As for the severity of the disease, none of the 10 patients with stage 5-6 hepatitis carried the HLA-DRB1*11 allele, in line with what was observed in nontransplant subjects. Our results suggest that in posttransplant recurrent hepatitis C, immunogenetic factors are relevant in determining HCV infection outcome.

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.