Influence of anti-HLA antibodies and positive T-lymphocytotoxic crossmatch on survival and graft rejection in human liver transplantation

Liver Transplantation in Recipients With a Positive Crossmatch: A Retrospective Single-Center Match-Pair Analysis

A positive crossmatch (XM+) is considered a contraindication to solid abdominal organ transplantation except liver transplantation (LT). Conflicting reports exist regarding the effects of XM+ on post-transplant outcomes. The goal of this retrospective single-center analysis is to evaluate the influence of XM+ on relevant outcome parameters such as survival, graft rejection, biliary and arterial complications. Forty-nine adult patients undergoing LT with a XM+ between 2002 and 2017 were included. XM+ LT recipients were matched 1:2 with crossmatch negative (XM-) LT recipients based on the balance of risk (BAR) score. Patient and graft survival were compared using Kaplan-Meier survival analysis and the log-rank test. Comparative analysis of clinical outcomes in XM+ and XM- groups were conducted. Patient and graft survival were similar in XM+ and XM- patients. Rejection episodes did not differ either. Recipients with a strong XM+ were more likely to develop a PCR+ CMV infection. A XM+ was not associated with a higher incidence of biliary or arterial complications. Donor age, cold ischemia time, PCR+ CMV infection and a rejection episode were associated with the occurrence of ischemic type biliary lesions. A XM+ has no effects on patient and graft survival or other relevant outcome parameters following LT.

Influence of Preformed Antibodies in Liver Transplantation

The significance of human leukocyte antigen (HLA) matching and preformed donor-specific antibodies (DSAs) in liver transplantation remains unclear. The aim of this study was to analyze the presence of DSAs in a large cohort of 810 liver recipients undergoing liver transplant to determine the influence on acute (AR) or chronic liver rejection (CR), graft loss and allograft survival. DSAs were identified using complement dependent cytotoxicity crossmatch (CDC-CM) and multiplexed solid-phase-based flow cytometry assay (Luminex). CDC-CM showed that a 3.2% of liver transplants were positive (+CDC-CM) with an AR frequency of 19.2% which was not different from that observed in negative patients (-CDC-CM, 22.3%). Only two patients transplanted with +CDC-CM (7.6%) developed CR and suffered re-transplant. +CDC-CM patients showed a significantly lower survival rate compared to -CDC-CM patients (23.1% vs. 59.1%, p = 0.0003), developing allograft failure within the first three months (p < 0.00001). In conclusion, we have demonstrated a relationship between the presence of preformed DSAs and the low graft liver survival, indicating the important role and the potential interest of performing this analysis before liver transplantation. Our results could help to detect patients with an increased risk of graft loss, a better choice of liver receptors as well as the establishment of individualized immunosuppressive regimens.

Pretransplant donor-specific anti-HLA antibodies as predictors of early allograft rejection in ABO-compatible liver transplantation

The significance of preexisting donor-specific HLA antibodies (HLA-DSAs) for liver allograft function is unclear. Our previous studies have shown that humoral alloreactivity frequently accompanies acute cellular rejection (ACR). In the present study, we set out to determine whether pretransplant HLA-DSAs correlate with clinically significant ACR in the first 90 days after transplantation and, if so, to determine their predictive values. Class I HLA-DSAs and class II HLA-DSAs were determined by single-antigen bead flow cytometry for 113 consecutive adult transplants. A statistical analysis was performed for data from 109 consecutive patients with graft survival greater than or equal to 90 days. All patients who developed biochemical graft dysfunction underwent liver biopsy for hematoxylin-eosin and complement component 4d staining. Cox proportional hazards models and associated hazard ratios revealed a significant association of pretransplant HLA-DSAs with clinically significant ACR: this association started with a mean fluorescence intensity (MFI) as low as 300 for both class I (hazard ratio = 2.7, P  < 0.01) and class II (hazard ratio = 6.0, P  < 0.01). Pretransplant HLA-DSAs were associated with an increased risk of ACR: P  < 0.01 for class I (42% versus 18%), P  < 0.001 for class II (37% versus 7%), and P  < 0.001 for either class I or II (36% versus 3%). Class I or II HLA-DSAs with an MFI ≥ 1000 had the best positive predictive value for clinically significant ACR at 46%, whereas class I or II HLA-DSAs with an MFI ≥ 300 had the best negative predictive value at 97.1%. Although our study was based on consecutive patients, it was limited by the relatively low number of single-center subjects. In conclusion, the present study indicates that pretransplant HLA-DSAs, even at low levels of allosensitization, correlate with the risk of clinically significant ACR. Our findings suggest that anti-human leukocyte antigen antibodies could serve as donor-specific markers of immunoreactivity to the liver graft.

Liver transplantation with a strongly positive crossmatch: case study and literature review

A positive crossmatch has been associated with increased risk in liver transplantation. To study the clinical significance of preformed donor-specific human leukocyte antigen antibodies (DSAs) in liver transplantation, we reviewed patients who underwent liver transplantation with a strongly positive flow cytometry crossmatch. DSAs were evaluated with a Luminex solid phase assay. The complement-fixing ability of DSAs was tested with a complement component 1q (C1q) assay. Using an assay correlation between complement-dependent cytotoxicity crossmatch, flow cytometry crossmatch, and DSA results, we reviewed the effects of DSAs on the outcomes of our patients as well as reported cases in the literature. Five of 69 liver recipients had a strongly positive crossmatch: 4 had a positive T cell crossmatch [median channel shift (MCS) = 383.5 ± 38.9], and 5 had a positive B cell crossmatch (MCS = 408.8 ± 52.3). The DSAs were class I only in 1 patient, class I and II in 3 patients, and class II only in 1 patient. Cholestasis, acute rejection, or both were observed in 3 of the 4 patients with a positive T cell crossmatch with an MCS approximately greater than 300. The C1q assay was positive for 3 patients. Two had either persistent cholestasis or early acute rejection. One patient who was treated with preemptive intravenous immunoglobulin had an unremarkable outcome despite a positive C1q result. One of the 2 patients with a negative C1q assay experienced persistent cholestasis and early and recurrent acute rejection; the other had an unremarkable outcome. None of the patients died or lost a graft within the first year of transplantation. Our study suggests that human leukocyte antigen antibody screening, flow cytometry crossmatch MCS levels, DSA mean fluorescent intensity levels, and C1q assays may be useful in assessing the risk of antibody-mediated rejection and timely interventions in liver transplantation.

Significance of true-positive and false-positive pretransplantation lymphocytotoxic crossmatch in primary liver allograft outcomes

BACKGROUND

At the time of transplantation, a recipient's serum is tested against the prospective donor's lymphocytes to identify specific reactivity and to look for a donor-specific crossmatch (CXM). Here, we investigated the relationship between the pretransplantation lymphocytotoxic CXM results and the long-term outcome of liver transplantation at a single center.

METHODS

From October 1998 to April 2011, medical records, laboratory data, and pretransplantation lymphocytotoxic CXM results were collected from 1133 consecutive liver transplant recipients.

RESULTS

We performed liver transplantations on 80 (7.1%) patients after a true-positive CXM (t+CXM). The t+CXM group exhibited higher initial aminotransferase levels immediately after transplantation compared with a negative CXM group. However, no significant differences in rejection, biliary or vascular complications, viral disease recurrence, or de novo malignancies were found. Although overall graft and patient survival did not differ between the groups, liver-specific graft survival was inferior in the t+CXM group. It was also found that, in 42 (3.7%) recipients, initially positive results converted to final negative results after the elimination of immunoglobulin M autoantibodies. We defined this subpopulation as a false-positive CXM. Significantly decreased posttransplantation aminotransferase levels with a higher incidence of de novo malignancies were observed in this group compared with negative controls.

CONCLUSION

Our findings demonstrate that t+CXM transplants show increased aspartate aminotransferase and alanine aminotransferase peak immediately after transplantation, which influences liver-specific graft outcomes. Additionally, the presence of circulating immunoglobulin M autoantibodies against recipients' own antigens may be protective in liver grafts. However, this may be a predisposing factor for de novo malignancies.

The effect of a positive T-lymphocytotoxic crossmatch on clinical outcomes in adult-to-adult living donor liver transplantation

Purpose

There is controversy concerning the effect of a positive T-lymphocytotoxic crossmatch (TLC) on clinical outcomes in adult living donor liver transplantation (LDLT). The aim of this study was to investigate the effect of TLC on clinical outcomes in LDLT and to determine how long a pretransplant positive TLC continues after liver transplantation (LT).

Methods

Between January 2005 and June 2010, 219 patients underwent adult LDLT at National Cancer Center. The TLC test was routinely performed before LDLT. TLC test results were positive in 8 patients (3.7%). Patients were divided into 2 groups according to the result of TLC: positive TLC (n = 8) and negative TLC (n = 211) groups. All patients with a pretransplant positive TLC (n = 6) underwent a TLC test every week until negative conversion of TLC, except 2 patients who refused to receive the TLC test.

Results

Acute cellular rejection, surgical complications and patient or graft survival were not significantly different between both groups. All patients with a positive TLC (n = 6) had a posttransplant negative TLC. The median time to negative conversion of TLC was 1.5 weeks (range, 1 to 3 weeks).

Conclusion

A pretransplant positive TLC does not affect clinical outcomes in adult LDLT. Moreover, T-lymphocytotoxic cross-reactivity disappeared within 3 weeks (range, 1 to 3 weeks) after LT.

Significance of C4d staining in ABO-identical/compatible liver transplantation

Complement degradation product C4d has become an important marker of humoral or antibody-mediated rejection in renal and heart allograft biopsies. Although there have been several reports on the detection of C4d in liver allografts, the significance of C4d in liver transplantation and its relationship with humoral rejection are still not clear. We investigated the frequency and pattern of C4d staining in liver allograft biopsies with reference to preoperative lymphocyte crossmatch tests, which detect donor-reactive lymphocyte antibody. Survival rates at 5 years were 77% for crossmatch-negative patients and 53% for crossmatch-positive patients (P=0.009). In crossmatch-negative patients, reproducible positive staining was obtained in 28 of 86 (33%) biopsies taken within 90 days after transplantation and 33 of 96 (34%) biopsies 90 days or after transplantation. Most C4d staining was observed in the portal areas, and no clear correlation was observed between C4d positivity and histological diagnosis. In crossmatch-positive patients, 9 of 11 (82%) biopsies showed positivity for C4d. C4d stained perivenular areas as well as portal areas. Histology of crossmatch-positive patients included acute rejection and cholangitis, but did not include periportal changes that were seen in humoral rejection in ABO-incompatible liver transplantation. In summary, focal C4d deposition was seen in various types of liver allograft injury and had little clinical impact on crossmatch-negative patients, but extensive C4d staining in crossmatch-positive patients may be associated with humoral rejection and poor graft survival.

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.

Marked Differences in acute cellular rejection rates between living-donor and deceased-donor liver transplant recipients

BACKGROUND

: Due to ongoing organ donor shortage, an increasing number of adult live-donor liver transplants (LDLT) are being performed. The aims of this study were to compare the incidence of ACR between recipients of live- and deceased-donor liver transplants, and to note any differences in ACR among related and unrelated living-donor recipients.

METHODS

: Sixty-four adults undergoing LDLT between 1998-2001 were closely matched with a deceased recipient. Statistical comparisons in ACR between the live- and deceased-donor groups were based on the differences between the ACR rates of each LDLT patient and the corresponding matched deceased recipient. Analyses were performed separately for pairs in which the living donor was not related to the recipient, was a nonsibling relative, or was a sibling.

RESULTS

: Live- and deceased-donor recipients underwent a similar number of liver biopsies. In all, 16/50 (32%) of the biopsied LDLT patients had ACR compared to 36/49 (73%) of the deceased-donor recipients. ACR rates of living donors and their deceased-donor matches did not differ significantly for the unrelated living donors, but did differ for the nonsibling related (P=0.03) and the sibling LDLT (P=0.03). The results were similar when comparing rates of high-degree ACR for unrelated, nonsibling related, and sibling pairs. High-degree ACR differences in the sibling LDLT group were significantly greater than in the nonsibling group (P=0.05).

CONCLUSIONS

: Rates of ACR and high-degree ACR are decreased in living-related liver transplant recipients. This difference is likely genetically related as ACR rates are lower in recipient-donor pairs of increasing genetic similarity.

Human Leukocyte Antigen Antibodies for Monitoring Transplant Patients

Human leukocyte antigen (HLA) antibody-mediated hyperacute rejection has dramatically decreased since the clinical introduction of crossmatch technology. However, the role of HLA antibody in acute and chronic rejection remains unclear. In this article, we cite publications to show the correlation between HLA antibody and allograft rejection. Potential pathological mechanisms of antibody-mediated rejection are also proposed and the rationale of commonly used HLA antibody detection techniques are introduced. The advantages and disadvantages of these technologies are further discussed in detail. We conclude that owing to the recent availability of improved antibody detection methods, a causal relationship between HLA antibodies and allograft rejection is now considered to exist.

Liver recipients harbouring anti-donor preformed lymphocytotoxic antibodies exhibit a poor allograft survival at the first year after transplantation: experience of one centre

In this retrospective study, we analyzed the effect of the presence of anti-donor preformed alloantibodies in 268 liver allograft transplants. Crossmatches were performed by complement-dependent cytotoxicity (CDC) assay and HLA antibody screening by flow cytometry (FlowPRA). Positive anti-donor crossmatch was detected in 5.2% of transplants. Acute rejection frequency in +CDC crossmatch patients was not different from that observed in -CDC crossmatch patients. None of the patients transplanted with +CDC crossmatch developed chronic rejection, but they showed a significantly lower allograft survival rate, and the majority of them had allograft failures before the end of the first post-transplant year, mainly within the 3 first months. Indeed, positive FlowPRA determination was concordant with data from the CDC assay. In conclusion, these findings show a direct correlation between the presence of anti-donor preformed antibodies and a poor allograft survival in liver transplant.

Are preformed antibodies to biliary epithelial cells of clinical importance in liver transplantation?

During acute liver allograft rejection, most of the tissue damage to bile duct epithelium is thought to occur as a consequence of direct immunologic injury by T-cell-mediated immune effector mechanisms. However, the role of antibodies to biliary epithelial cells (BECs) in liver transplant rejection is not known. We therefore investigated cross-match sera obtained immediately before liver transplantation from 95 patients for the presence of BEC-reactive antibodies to determine their association with acute rejection. BECs were isolated from one normal healthy liver. Antibody binding was detected by using flow cytometric analysis. Donor lymphocyte-specific cross-matches using complement-dependent cytotoxicity (CDC) and flow cytometric assays also were performed. The 2-year patient survival rate in this study was 86.3%. Eleven patients were positive for either CDC or flow cytometric cross-matches. BEC antibodies were detected in 41 serum samples (43.2%). Patients with BEC antibodies experienced acute rejection more frequently (65.9%) compared with 42.5% without antibodies (P <.03). HLA specificity determinations indicated that in 5 of 41 cases, anti-BEC reactivity was caused by HLA antibodies. No correlations between the presence of BEC antibodies and patient survival and the occurrence of cholangitis and nonsurgical bile duct strictures were found within 2 years of follow-up. In conclusion, preformed antibodies to BECs are associated with acute rejection. Thus, the presence of these antibodies before transplantation may facilitate acute liver graft rejection.

Positive T lymphocytotoxic cross-match in living donor liver transplantation

The influence of lymphocytotoxic cross-match on survival or acute rejection in living donor liver transplantation (LDLT) has not been well examined. We analyzed 133 consecutive adult LDLT cases and assessed patient survival and acute rejection rates. Patients with a positive T lymphocytotoxic cross-match (n = 12) had a significantly higher chance of rejection within 6 weeks of LDLT (67% versus 28%, P <.001). All of the rejection episodes were successfully treated with bolus methylprednisolone therapy or anti-T cell monoclonal antibody. T lymphocytotoxic cross-match-positive grafts had no influence on patient survival (79% versus 90% at 3 years, P =.91). The results show that a positive cross-match graft should not be considered a contraindication for LDLT.

Analysis of the United Network for Organ Sharing database comparing renal allografts and patient survival in combined liver-kidney transplantation with the contralateral allografts in kidney alone or kidney-pancreas transplantation

BACKGROUND

Combined liver-kidney transplantation (LKT) is the accepted treatment for patients with liver failure and irreversible renal insufficiency. Controversy exists as to whether simultaneous LKT with organs from the same donor confers immunologic and graft survival benefit to the kidney allograft. This study compares the outcomes of simultaneous LKT with the contralateral kidneys used for kidney alone transplantation (KAT) or combined pancreas-kidney transplantation (PKT) to understand the factors that account for the differences in survival.

METHODS

From October 1987 to October 2001, LKTs with organs from 899 cadaver donors were reported to the United Network for Organ Sharing; 800 contralateral kidneys from these donors were used in 628 KAT and 172 PKT recipients. These 800 paired control patients were the basis of this analysis.

RESULTS

Graft and patient survival rates were lower among LKT recipients compared with KAT (P<0.001) and PKT recipients (P<0.001), because of a higher patient mortality rate during the first 3 months posttransplant. Among human leukocyte antigen-mismatched transplants, LKT recipients demonstrated the highest 1-year rejection-free survival rate (LKT 70%, KAT 61%, and PKT 57% ) (P=0.005 vs. KAT, P=0.005 vs. PKT). There was a lower incidence of renal graft loss resulting from chronic rejection among LKT recipients (LKT 2% vs. KAT 8% vs. PKT 6%, P<0.0001).

CONCLUSIONS

Patients undergoing LKT exhibit a higher rate of mortality during the first year posttransplant compared with patients undergoing KAT and KPT. Analysis of the data indicates an allograft-enhancing effect of liver transplantation on the renal allograft.

Significance of positive cytotoxic cross-match in adult-to-adult living donor liver transplantation using small graft volume

A positive cross-match in cadaveric liver transplantation is relatively acceptable, but its role in living donor liver transplantation (LDLT) is less well known. The aim of this study is to examine the significance of cytotoxic cross-match in adult-to-adult LDLT using small-for-size grafts. Forty-three adult-to-adult LDLTs were performed at Seoul National University Hospital (Seoul, Korea) from January 1999 to July 2001. Subjects consisted of 27 men and 16 women with an average age of 45.4 years. Average liver graft weight was 565.3 +/- 145.7 g, and average graft-recipient weight ratio (GRWR) was 0.89% +/- 0.20%. HLA cross-match testing by lymphocytotoxicity and flow cytometry was performed routinely preoperatively. Factors that may influence survival, such as age; sex; blood group type A, type B, type O compatibility; cytotoxic cross-match; donor age; surgical time; cold ischemic time; and GRWR, were analyzed. Nine patients (20.9%) died in the hospital. There was a greater in-hospital mortality rate in women than men (37.5% v 11.1%; P = .049). The extra-small-graft group (0.54% < or = GRWR < 0.8%; n = 14) showed greater in-hospital mortality rates than the small-graft group (0.8% < or = GRWR < or = 1.42%; n = 29; 42.9% v 10.3%; P = .022). A positive cross-match was detected in 4 women transplant recipients, and 3 of these patients belonged to the extra-small-graft group. All patients with a positive cross-match died of multiorgan failure after early postoperative acute rejection episodes. Positive cross-match was the only significant factor in multivariate analysis (P = .035). In conclusion, when lymphocytotoxic cross-match and flow cytometry are significantly positive, adult-to-adult LDLT using small-for-size grafts should not be performed.

Influence of panel-reactive antibodies on posttransplant outcomes in lung transplant recipients

BACKGROUND

Panel-reactive antibody (PRA) is used to estimate the degree of humoral sensitization in the recipient before transplantation. Although pretransplant sensitization is associated with increased complications in other solid organ transplant recipients, less is known about the outcome of sensitized lung transplant recipients. Therefore, we sought to determine the impact of elevated pretransplant PRA on clinical outcomes after lung transplantation.

METHODS

The records of the first 200 lung transplant operations performed at Duke University Medical Center were reviewed. The outcomes of sensitized patients, PRA greater than 10% before transplantation (n = 18), were compared with the outcomes of nonsensitized patients.

RESULTS

Sensitized patients experienced a significantly greater number of median ventilator days posttransplant (9 +/- 8) as compared with nonsensitized recipients (1 +/- 11; p = 0.0008). There were no significant differences between the number of episodes of acute rejection; however, there was a significantly increased incidence of bronchiolitis obliterans syndrome occurring in untreated sensitized recipients (56%) versus nonsensitized (23%; p = 0.044). In addition, there was a trend towards decreased survival in the sensitized recipients, with a 2-year survival of 58% in sensitized recipients as compared with 73% in the nonsensitized patients (p = 0.31).

CONCLUSIONS

Sensitized lung transplant recipients experience more acute and chronic complications after transplantation. These patients probably warrant alternative management strategies.

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.

Flow cytometric detection of HLA antibodies using a spectrum of microbeads

We describe here the use of HLA antigen coated beads for specificity and class determination of HLA antibodies by flow cytometry. The HLA specificity of antibodies was determined by use of beads containing eight levels of fluorescence. HLA antigens isolated from eight cultured cells were coated onto these beads so that each bead was the equivalent of one cell. By using four sets of eight beads, an equivalent of 32 cells could be examined in four test tubes. A total of 76 class I and 25 class II specificities could be determined by the 32 class I bead-panel and 32 class II bead-panel used, respectively. We noted no cross-reactivity of reactions between class I and II. The sensitivity of the test was shown to be higher than that of the standard cytotoxicity by dilution experiments and detection of additional cross-reacting antigens. By use of these coated beads, we achieved improved standardized detection of HLA antibodies. Antigen-coated beads have several advantages over the use of spleens or lymphocytes. (a) A highly selected panel of antigens can be routinely used. (b) Class I and class II antibodies can be readily distinguished from each other, even when they are present as mixtures in one serum. (c) Non-HLA antibodies are not detected because the beads do not have any other antigens than HLA on them. (d) The quantity of antigens coated on beads is more uniform than that found in cells from different individuals. (e) Beads are more convenient for storage and daily use.

Postoperative flow cytometry crossmatch in living donor liver transplantation: clinical significance of humoral immunity in acute rejection

BACKGROUND

The role of humoral immunity in acute rejection in solid organ transplantation remains controversial, although it is known that the presence of antidonor antibodies may precipitate graft rejection. We investigated the clinical relevance of antidonor humoral immunity for living donor liver transplantation (LDLT) by means of flow cytometry crossmatch (FCXM).

METHODS

T cell FCXM using fresh donor peripheral lymphocytes was performed before and up to 1 month after LDLT in 58 patients. Ten patients received ABO-incompatible grafts. IgM and IgG antidonor antibodies were analyzed in relation to clinical acute rejection as defined by liver function tests with or without histological evidence.

RESULTS

Pretransplantation FCXM was positive for five patients (8.6%), resulting in two cases of positive posttransplantation FCXM and two rejection episodes. Twelve patients (20.7%) showed positive posttransplantation FCXM. The incidence of acute rejection within 1 month was 100% in FCXM-positive patients and 17.4% in FCXM-negative patients (P<0.001). Thirteen (76.5%) of 17 rejection episodes in ABO-compatible cases were associated with concomitant antidonor IgM antibody. IgG antibody was also identified in six of these episodes. Antidonor antibodies disappeared after rejection treatments in all cases, but with some delay in clinical improvement. On the other hand, no antidonor antibodies were detected in any of the four rejection episodes in ABO-incompatible cases.

CONCLUSIONS

Early acute rejection in LDLT is significantly associated with antidonor T cell antibody formation in ABO-compatible cases. This suggests a definite role for donor-specific humoral immunity in acute rejection. Rejection episodes without antidonor antibodies may suggest graft injury by pure cellular immunity, or possibly the presence of humoral immunity triggered by antigens not present on donor T cells.

Cerebral changes in hepatic encephalopathy

Hepatic encephalopathy (HE) accompanied by an impairment of consciousness from orientation disorder (grade II) to coma (grade IV) is considered to be overt HE and is treated as an emergency. However, subclinical hepatic encephalopathy (SHE) can be detected by sensitive and quantitative neuropsychological examinations in cirrhotic patients without overt HE. The introduction of the SHE concept is clinically important for preventing the deterioration of SHE (grades 0 and I) to overt HE (grade II and more severe), prolonging the compensated state of cirrhosis without its deterioration to hepatic failure, and the continuation of patient treatment at home. We developed a new diagnostic method for SHE using a quantitative neuropsychological test, with the computerization of all operations. Evaluations of cerebral function and morphology are useful for the determination of the pathophysiology of HE, and assist the diagnosis of SHE. The latencies of the P3 wave in the visually evoked potential and the P300 wave in the event-related potential are prolonged in cirrhotic patients with SHE and are well expressed in three-dimensional coloured topograms (brain mapping). Automated polysomnographic analysis is useful for continuous-monitoring electroencephalograms (EEG) and for the detection of the sleep disturbance observed in cirrhotic patients with SHE. Brain atrophy in computed tomography (CT), magnetic resonance imaging (MRI) and high signals in the basal ganglia in the MR-T1-weighted images have frequently been observed in patients with SHE. The reduction of regional cerebral blood flow (rCBF) by 99mtechnetium-1, 1-ethylcysteinate dimer (99mTc-ECD)-single photon emission computed tomography (SPECT) and the choline/N-acetylaspartic acid ratio by proton-magnetic resonance spectroscopy (1H-MRS) were observed in the hippocampus in patients with SHE. These approaches (cerebral function tests and imaging diagnoses of the brain) can also be used to evaluate the effectiveness of treatments for HE; for example, branched-chain amino acid (BCAA) was shown by automated continuous polysomnographic analysis to be a psychotropic drug which acts directly on the central nervous system and the clinical significance of choline administration to HE patients is now being evaluated by 1H-MRS and neuropsychological tests.

The effect of a positive T-lymphocytotoxic crossmatch on hepatic allograft survival and rejection

The influence of crossmatching in liver transplantation is still controversial, and at present, our unit does not alter management according to the result of standard lymphocytotoxicity testing. This study retrospectively assessed outcome of grafts transplanted in the presence of preformed antidonor cytotoxic antibody. One hundred twelve patients undergoing their first orthotopic liver transplantation had results available (mean follow-up: 18 months). Twelve patients had a positive crossmatch and 100 negative. The 1-year graft survival was 58% in the positive crossmatch group, compared with 81% in the negative crossmatch group (P = .02). The 1-year patient survival was 83% in the positive crossmatch group compared with 90% in the negative group (P = .41). Acute cellular rejection occurred in 6 of 7 (86%) grafts surviving more than 7 days in the positive crossmatch group compared with 46 of 88 (52%) grafts in the negative group (P = .09). However, episodes of further acute cellular rejection requiring treatment occurred in 4 of the 6 grafts in the positive crossmatch group but in only 4 of the 46 grafts with a negative crossmatch (P = .0006). The authors conclude that evidence exists in our population that preformed antidonor antibodies adversely affect the outcome of hepatic allografts but not patient survival.