Donor-Specific HLA Antibodies in Living Versus Deceased Donor Liver Transplant Recipients.

With less ischemia, improved donor selection and controlled procedures, living donor liver transplantation (LDLT) might lead to less HLA donor-specific antibody (DSA) formation or fewer adverse outcomes than deceased donor liver transplantation (DDLT). Using the multicenter A2ALL (Adult-to-Adult Living Donor Liver Transplantation Cohort Study) biorepository, we compared the incidence and outcomes of preformed and de novo DSAs between LDLT and DDLT. In total, 129 LDLT and 66 DDLT recipients were identified as having serial samples. The prevalence of preformed and de novo DSAs was not different between DDLT and LDLT recipients (p = 0.93). There was no association between patient survival and the timing (preformed vs. de novo), class (I vs. II) and relative levels of DSA between the groups; however, preformed DSA was associated with higher graft failure only in DDLT recipients (p = 0.01). De novo DSA was associated with graft failure regardless of liver transplant type (p = 0.005) but with rejection only in DDLT (p = 0.0001). On multivariate analysis, DSA was an independent risk factor for graft failure regardless of liver transplant type (p = 0.017, preformed; p = 0.002, de novo). In conclusion, although similar in prevalence, DSA may have more impact in DDLT than LDLT recipients. Although our findings need further validation, future research should more robustly test the effect of donor type and strategies to mitigate the impact of DSA.

Proposed Diagnostic Criteria for Chronic Antibody-Mediated Rejection in Liver Allografts.

Donor-specific alloantibodies (DSA) can cause acute antibody-mediated rejection (AMR) in all solid organ allografts. However, long-term outcome in patients with posttransplant DSA needs further study. We retrospectively evaluated prospectively collected paired serum, tissue, and data on 45 matched DSA- positive [DSA+; mean florescence intensity (MFI) ≥10,000] and -negative (DSA-) recipients of a primary liver-only allograft from January 2000 to April 2009. Blinded histopathologic evaluation demonstrated that DSA+ versus DSA- patients were more likely to have subtle inflammation and unique patterns of fibrosis, despite normal or near-normal liver function tests. Stepwise multivariable modeling developed a score (putatively named the chronic AMR [cAMR] score) that included interface activity, lobular inflammation, portal tract collagenization, portal venopathy, sinusoidal fibrosis, and hepatitis C virus status. The score was developed (c = 0.811) and cross-validated (c = 0.704) to predict allograft failure. Two cutoffs were employed to optimize sensitivity and specificity (80% each); a value >27.5 predicted 50% 10-year allograft failure. We propose chronic AMR as a potential new entity defined by (1) a high cAMR score, (2) DSA, and (3) elimination of other potential causes of a similar injury pattern. In conclusion, cAMR score calculation identified liver allograft recipients with DSA at highest risk for allograft loss, although independent validation is needed.

Impact of IgG3 subclass and C1q-fixing donor-specific HLA alloantibodies on rejection and survival in liver transplantation.

Recent literature confirms donor-specific HLA alloantibodies (DSA) impair 5-year survival in some but not all liver transplant recipients. In an effort to improve DSA testing's association with rejection and death, we retrospectively evaluated 1270 liver transplant recipients for the presence of IgG3 and C1q-fixing DSA. In patients with preformed DSA, 29 and 51% had IgG3 and C1q-fixing DSA, respectively. In patients with de novo DSA, 62% and 67% had IgG3 and C1q-fixing DSA, respectively. When different types of DSA positive patients were compared to DSA negative patients, multivariable analysis showed that IgG3 DSA positivity had the highest numerical hazard ratio for death (IgG3: HR = 2.4, p < 0.001; C1q: HR = 1.9, p < 0.001; standard DSA: HR = 1.6, p < 0.001). Similarly, multivariable analysis demonstrated de novo IgG3 DSA positivity compared to no DSA had the highest hazard ratio for death (IgG3: HR = 2.1, p = 0.004; C1q: HR = 1.9, p = 0.02; standard DSA: HR = 1.8, p = 0.007). Preformed C1q-fixing class II DSA showed the strongest correlation with early rejection. In conclusion, preformed and de novo IgG3 subclass DSA positive patients had the highest absolute HR for death in side-by-side comparison with C1q and standard DSA positive versus DSA negative patients; however, IgG3 negative DSA positive patients still had inferior outcomes compared to DSA negative patients.

Impact of the presence and duration of donor-specific antibodies on renal function.

BACKGROUND: Although anti-human leukocyte antigen (HLA) antibodies (DSA) is associated with graft loss, 3 things remain unclear: whether the duration and strength of DSA affect renal function; what mean fluorescence intensity (MFI) cut-off should be used; and whether the DSA effect is additive in case of multiple DSAs. METHODS: A study was made of 63 patients who received living donor kidney transplants with clonal deletion protocol and were followed up for 18 months with reduced doses of immunosuppressants. DSA was tested for monthly, using Luminex Mixed and Single Antigen beads (One Lambda, Inc., Canoga Park, CA, USA). Decrease of estimated glomerular filtration rate (eGFR) was obtained at baseline and 18 months after transplantation. Association of renal damage and DSAs was compared using several DSA models with several MFI cut-offs. RESULTS: Additive DSA models always showed better association with renal damage than comprehensive models. When calculating the DSA effect in additive models, "proxy-area under the curve" (AUC)-a triangular approximation of the actual AUC-showed better association with renal damage than did DSA duration (R(2) = 0.105 vs 0.087). Adjusting for other factors, 27% of the variation of GFR change was explained by proxy-AUC. No significant change of association occurred if the MFI cut-off level changed from 1000 to 3000. CONCLUSION: Our results support the association of DSA with development of longitudinal renal damage. The clinical interpretation may be similar at MFI cut-offs of 1000, 2000, and 3000. An additive DSA effect may be expected in patients with multiple DSAs. Our study suggests the importance of frequently checking for DSA and reducing their MFI value to minimize renal damage by the antibodies.

De novo donor-specific HLA antibodies decrease patient and graft survival in liver transplant recipients.

The role of de novo donor-specific HLA antibodies (DSA) in liver transplantation remains unknown as most of the previous studies have only focused on preformed HLA antibodies. To understand the significance of de novo DSA, we designed a retrospective cohort study of 749 adult liver transplant recipients with pre- and posttransplant serum samples that were analyzed for DSA. We found that 8.1% of patients developed de novo DSA 1 year after transplant; almost all de novo DSAs were against HLA class II antigens, and the majority were against DQ antigens. In multivariable modeling, the use of cyclosporine (as opposed to tacrolimus) and low calcineurin inhibitor levels increased the risk of de novo DSA formation, while a calculated MELD score >15 at transplant and recipient age >60 years old reduced the risk. Multivariable analysis also demonstrated that patients with de novo DSA at 1-year had significantly lower patient and graft survival. In conclusion, we demonstrate that de novo DSA development after liver transplantation is an independent risk factor for patient death and graft loss.

High mean fluorescence intensity donor-specific anti-HLA antibodies associated with chronic rejection Postliver transplant.

In contrast to kidney transplantation where donor-specific anti-HLA antibodies (DSA) negatively impact graft survival, correlation of DSA with clinical outcomes in patients after orthotopic liver transplantation (OLT) has not been clearly established. We hypothesized that DSA are present in patients who develop chronic rejection after OLT. Prospectively collected serial serum samples on 39 primary OLT patients with biopsy-proven chronic rejection and 39 comparator patients were blinded and analyzed for DSA using LABScreen(®) single antigen beads test, where a 1000 mean fluorescence value was considered positive. In study patients, the median graft survival was 15 months, 74% received ≥ one retransplant, 20% remain alive and 87% had ≥ one episode of acute rejection. This is in contrast to comparator patients where 69% remain alive, and no patient needed retransplant or experienced rejection. Thirty-six chronic rejection patients (92%) and 24 (61%) comparator patients had DSA (p = 0.003). Chronic rejection versus comparator patients had higher mean fluorescence intensity (MFI) DSA. Although a further study with larger numbers of patients is needed to identify clinically significant thresholds, there is an association of high-MFI DSA with chronic rejection after OLT.

Clonal deletion using total lymphoid irradiation with no maintenance immunosuppression in renal allograft recipients.

A total of 69 individuals received a kidney from a living donor after a TLI-based clonal deletion protocol with no post-transplant maintenance immunosuppression planned. If needed, immunosuppression was started on a patient-specific basis, adding one drug at a time, a strategy we AWN". call "Drugs Added When Needed," or "DAWN. Following this strategy, at last follow-up 40 of the 69 patients (58%) had to be rescued by conventional immunosuppression, 23 (33%) had to be started on daily prednisone and six (9%) remained with no maintenance immunosuppression. The overall rate of de novo donor-specific antibody produced was 36% (in 25 of the 69 patients), and mean time to detection was about four months. The incidence of acute rejection episodes that displayed humoral components was 27% (19 cases), of which 14 were pure antibody-mediated rejection, five combined antibody- and T-cell-mediated rejection, and six were episodes (9%) of pure T-cell-mediated rejection. Finally, this study shows that although complete clonal deletion was not achieved, an important proportion of patients--42%, or 29 of the original 69--could be maintained with prednisone alone or even with no immunosuppression for a total mean follow-up of 13.3 months. Moreover, 16 patients with recent follow-up are surviving with no maintenance immunosuppression or just on prednisone. The mean serum creatinine at last follow-up for these 16 patients is 1.33 +/- 0.2 mg/dL with a mean follow-up of 19.3 months. Clonal deletion can be used to transplant patients without maintenance immunosuppression, adding drugs only as needed.

Donor-specific HLA antibody response in clonal deletion.

1. A total of 61 patients were treated with a clonal deletion protocol and transplanted without planned post-transplant immunosuppression. 2. Twenty-nine (48%) patients did not develop any donor-specific anti-HLA antibodies after the transplant, with a median follow-up of 158 days and a mean sCr of 2.1 mg/dL at the last follow-up. 3. Only 23% of the patients who received a DST of 60 mL produced DSA after the transplant, while 68% of the patients who received a bigger DST dose did. 4. Small doses of donor-specific transfusions (60 mL) elicited smaller specific responses, allowing efficient deletion of the reacting clones, creating conditions in which donor-specific anti-HLA antibodies were not produced. 5. A better deleting agent is needed to achieve higher rates of success using the clonal deletion protocol.

Elimination of post-transplant donor-specific HLA antibodies with bortezomib.

We show the ability of bortezomib to remove donor-specific HLA antibody from kidney allograft patients, the drug acting as a proteasome inhibitor, providing targeted therapy against antibody-producing plasma cells. Ten out of thirteen patients (77%) experienced primary DSA reversal, and in the remaining three patients the MFI of their primary DSA was dramatically reduced. Bortezomib is a viable therapy to treat donor-specific HLA antibody in allograft recipients. The potential for long-term benefits--and complications--are still unknown. Prospective trials are being conducted at the University of Cincinnati, Cincinnati, OH; at the Mayo Clinic, Rochester, MN; and at IKDRC-ITS, Ahmedabad, India.