Lymphocytotoxic crossmatch in pediatric living donor liver transplantation

Long-term Clinical Relevance of De Novo Donor-Specific Antibodies After Pediatric Liver Transplantation

BACKGROUND

Anti-HLA antibodies and especially donor-specific antibodies (DSA) play a significant role in graft survival after solid organ transplantation. Their impact on long-term survival in adult liver transplantation (LT) is controversial, but they may be a risk factor. The effects of DSA after pediatric LT are still unclear.

METHODS

We performed a retrospective evaluation of DSA in sera from 43 children who had received transplants at our tertiary center. Twenty-four patients had good long-term clinical and laboratory graft function (group 1), whereas 19 LT recipients suffered from histologically confirmed and clinically relevant chronic allograft rejection (group 2); 16 of these have already undergone retransplantation due to graft dysfunction. Inclusion criteria were availability of sera before the first LT to identify preformed antibodies in case of DSA positivity after LT and long-term follow-up at our institution. Sera were analyzed for anti-HLA antibodies using Luminex single antigen beads, where a mean fluorescence intensity value of more than 1500 was considered positive.

RESULTS

The prevalence of DSA was 33% for group 1 and 68% for group 2. Antibodies were predominantly HLA class II. Values of mean fluorescence intensity were comparable in both groups. Only one of the DSA+ ve patients from group 1 exhibited preformed antibodies. In conclusion, pediatric patients with chronic rejection revealed a higher rate of de novo DSA, especially of HLA-class II DSA. Further studies are necessary to confirm these data with a larger pediatric cohort.

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.