Positive Donor-specific Antibodies Research Articles

Effectiveness of IVIG Prophylaxis Against Antibody Mediated Rejection in Sensitized Renal Transplant Recipients.

Intro: With increasing transplantation of highly sensitized patients, we explored methods to decrease the incidence of antibody mediated rejection (AMR) in these high risk patients. Renal transplantation in highly sensitized patients is associated with as increased rate of rejection and poorer graft survival compared to unsensitized patients. In 2010, our center implemented IVIG prophylaxis against AMR in renal transplant recipients using 0.5gm/kg IVIG monthly for 4 doses. Initially, recipients with cPRA>80% received IVIG, which was revised in 2013 to cPRA>50 due to the positive impact of IVIG. We followed cross-match compatible, sensitized patients cPRA>50% for development of donor specific antibody (DSA), biopsy proven rejection, viral infections, neutropenia, graft loss, and death. Steroid-free immunosuppression (tacrolimus and mycophenolate) with Induction Thymoglobulin® and 2 doses of methylprednisolone was used unless patients developed rejection or new DSA. Minimum followup is 6 months. Results: IVIG prophylaxis significantly decreased the rate of AMR from 35% (15/43) to 9% (3/33) p=0.019 in treated vs. untreated recipients. Untreated patients include cPRA>50% 2006-2010 and cPRA 50-79% 2010-2013. In treated vs. untreated recipients, one year graft survival was 94% vs 91%. New DSAs decreased from 35% (15/43) to 21% (7/33). Patients with cPRA 50%-79% accounted for significant numbers of total positive DSAs (41%) and AMR (50%). IVIG prophylaxis was associated with a higher incidence of BK viremia (24% v 19%) and neutropenia (36% v 23%), but not CMV viremia (18% v 16%).Table: No Caption available.Data expressed as n(%) except N and Mean cPRA. Graft Loss defined as within 1yr. Conclusions: 1) In sensitized renal transplant recipients (cPRA>50%), 4 monthly doses of IVIG was effective as prophylaxis against AMR over more than 1 year post-transplantation. 2) IVIG prophylaxis also appears to decrease the incidence of new DSAs. 3) IVIG prophylaxis did not impact the incidence of ACR.

Coefficient of Variation of Sirolimus and Tacrolimus Levels Is Associated With Acute Rejection, Donor Specific Antibodies, and Medication Nonadherence in Pediatric Renal Transplantation.

Purpose: We previously reported that a high tacrolimus (TAC) % coefficient of variation (CV%) in pediatric (Ped) kidney transplant (KTx) patients (pts) is associated with acute rejection (Rej), development of donor specific antibodies (DSA) and medication nonadherence (MNA). We sought to determine the predictive value of the CV% of sirolimus (SLR) and/or TAC on KTx Rej, DSA and MNA in Ped KTx pts on SLR and TAC. Methods: Trough levels of SLR and TAC obtained within a 6 month period prior to a KTx biopsy (Bx) were used to determine CV% in 37 Bxs in 23 high risk pts, 2-18 years old, on SLR and low-dose TAC. Bxs were graded by 2009 Banff criteria. MNA by self-report defined as > 20% missed doses. DSA positivity defined as > 1000 MFI by Luminex assay. Results: High median SLR CV% of 40.8% was significantly associated with Rej (Fig.1, p=0.0001). A cut-off SLR CV% of 25% determined by ROC analysis predicted pts that would have Rej (Fig. 1, p=0.0001). Median TAC CV% was not associated with Rej (p=0.15). Patients with high SLR CV% were significantly more likely to show high TAC CV% (Fig.2, upper right quadrant, p<0.03). In this subgroup of high SLR and TAC CV%, 18 of 21 Bxs (86%) were associated with rejection (p=0.005), 11 of 16 (69%) developed DSA (p=0.03) and 15 of 21 (71%) reported MNA (p=0.05).Figure: No Caption available.Conclusion: Among pts on SLR and low-dose TAC immunosuppression, a high SLR CV% is a strong predictor of rejection. Pts with high SLR CV% are significantly more likely to have high TAC CV%. Pts with elevations in both SLR and TAC CV% are more likely to report MNA and develop rejection and DSA. Thus, in Ped KTx pts, SLR and TAC CV% can be an important tool to monitor rejection and DSA associated with MNA. DISCLOSURES:Ettenger, R.: Grant/Research Support, Novartis, Bristol Myers Squibb.

Tacrolimus trough level at discharge predicts acute rejection in moderately sensitized renal transplant recipients.

Goal tacrolimus concentrations for the prevention of rejection in sensitized renal transplant recipients are not well established. We evaluated the association between discharge tacrolimus trough concentration and the incidence of biopsy-proven acute rejection (BPAR) in 216 moderately sensitized renal transplant recipients (negative flow crossmatch and positive donor-specific antibodies) treated with tacrolimus. At transplant, the mean±standard deviation (SD) peak panel-reactive antibody was 60±33 and median donor-specific antibody level was a mean fluorescence intensity of 710 (interquartile range, 328-1202). The mean±SD tacrolimus trough concentration at discharge (median postoperative day, 5; interquartile range, 4-7) was 7.6±3.7 ng/dL. Patients were divided into two groups based on a discharge tacrolimus trough concentration of 8 ng/mL. Baseline characteristics were similar between groups. Thirty-four (28.6%) of the 119 patients with a tacrolimus trough concentration less than 8 ng/mL and 19 (19.6%) of 97 patients with concentrations of 8 ng/mL or greater experienced BPAR during a median follow-up of 14±4.7 months (P=0.04). Adjusting for age, race, donor status, and peak panel-reactive antibody, a discharge tacrolimus trough concentration less than 8 ng/mL was significantly associated with a higher risk of BPAR (hazard ratio, 1.84; 95% confidence interval, 1.04-3.25; P=0.04). Serum creatinine, cytomegalovirus, BK viremia, or BK nephropathy at 1 year did not differ between groups. In a patient population predisposed to BPAR, discharge tacrolimus trough concentration less than 8 ng/mL was associated with a nearly two times greater risk of BPAR.

1021-LBP: The significance of donor-specific hla antibodies detected by C1Q-SAB or flow cytometry crossmatches in liver transplantation

Aim Unlike in other solid organ transplantations, the role of pre-existing antibodies to HLA in liver transplant is not well defined. The presence of alloantibody in liver transplantation has been thought to have no severe deleterious impact on grafts survival, therefore crossmatchings is not routinely performed prior to liver transplantations. Recent reports suggest a correlation between positive donor specific antibody (DSA) and adverse graft outcome leading to reassessment of these views. Detection of DSA by current solid phase immunoassays is highly sensitive and specific. The correlation between DSA detected by immunoassays and their relevance in flow cytometric crossmatch (FCXM), C1q testing and subsequent liver transplantation has not been analyzed. Methods We retrospectively examined the predictive value of detection of DSA by FCXM or C1q binding ability of the DSA from 175 liver transplant recipients. LABScreen Single Antigen (SAB) immunoassay revealed anti-HLA in 44 of 175 patients. These positive serum were tested by FCXM and C1q assays. Results In SAB positive patients, the sensitivity of FCXM in detecting DSA is 67% and the negative predictive value is 90.5%, whereas C1q tests revealed all DSAs identified by SAB were complement fixing. Two of the four patients with positive DSA detected by all three tests developed biopsy proven acute/subacute immune mediated (plasma cell) rejection. Two patients with positive DSA by C1q but negative by FCXM did not develop rejection over 8-month follow up period. Conclusions These data suggest DSA resulting in FCXM positivity can lead to liver allograft dysfunction, however clinical relevance of C1q assay liver transplantation is still uncertain given none of patients with positive C1q DSA and negative FCXM have developed rejection.

De novo Membranous Nephropathy in Renal Allograft Associated With Antibody-Mediated Rejection and Review of the Literature

A 71-year-old woman with unknown renal failure etiology received living donor transplantation had normal graft function for many years. At 11 years from transplantation, she developed nephrotic syndrome. Allograft biopsy showed membranous nephropathy (MN) and C4d positivity in the peritubular capillaries, suggestive of antibody-mediated rejection. At the time of nephrosis onset, she had new donor-specific antibody positivity. The case is unusual in that the diagnosis of de novo MN is based on evidence that she had antibody-mediated rejection. De novo MN remains relatively uncommon; we have reviewed the literature on this diagnosis.

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Aim The C1qScreen™ assay detects complement binding HLA antibodies. Recent studies suggest that the presence of C1q positive donor specific antibodies (DSA) is associated with poor post-transplant outcomes. However, in some patients with documented episodes of antibody mediated rejection or graft failure, C1q binding DSA are not detected by the C1qScreen™ suggesting poor assay sensitivity. The goal of this study was to develop an enhanced C1q assay to improve the detection of complement binding HLA DSA. Methods Nine patient sera with well characterized (using IgG single antigen bead (SAB) assay) post-transplant DSA were tested for C1q binding using the standard C1qScreen™ and three modified protocols: 1) extended incubation (EI), 2) wash modified (WM) and 3) anti-human globulin (AHG) C1q enhanced (ACE) protocol. The number of class I/II DSA detected and DSA MFI values obtained with each protocol were compared. Results The C1qScreen™ was positive for only 30% of Class I (9/30) and 52% of Class II (15/29) IgG DSA specificities. The average MFI DSA values were markedly reduced compared with the IgG-SAB assay. The EI and WM protocols exhibited higher average DSA MFI values (2.25 and 3.4 fold higher respectively) compared to the standard protocol but only 2 additional DSA specificities were detected. In contrast, the ACE protocol identified 10 additional Class I (19/30; 63%) and 4 additional Class II (19/29; 66%) DSA specificities with an average increase in DSA MFI of 4.7 fold when compared with the standard C1qScreen™. Conclusions The C1qScreen™ exhibits poor assay sensitivity and fails to adequately identify many post-transplant complement fixing HLA DSA. The sensitivity of the C1qScreen™ to detect DSA can be improved with various protocol modifications. The ACE protocol was the most sensitive of the assays tested and detected the majority of post transplant HLA DSA. Future studies will investigate the clinical significance of HLA DSA detected by the ACE protocol.

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Aim The presence of C1q antibodies may be important for assessing the risk of antibody mediated rejection (AMR) in solid organ transplants. We studied the correlation between the C1q-single antigen bead assay (C1q-SAB) with the long-incubation complement-dependent lymphocytotoxicity assay (CDC) and the IgG-single antigen bead assay (IgG-SAB). Methods 60 reference sera (38 Class I and 22 Class II) from the UCLA serum exchange program were characterized using the CDC, Luminex PRA (Gen-probe Inc.) and IgG-SAB (One Lambda Inc.) assays. We also tested pre- and post-transplant sera from 16 renal allograft recipients. All patients had persistent posttransplant DSA as demonstrated by the IgG-SAB assay. Results The C1q-SAB assay showed 85% concordance with the CDC assay as 15% of the CDC positive antibodies were negative in the C1q test. Correlation between the SAB MFI and C1q positivity showed that 90% of sera with the MFI of >18,000 in the IgG-SAB assay were C1q binding. A retrospective study of 16 renal transplant recipients developing post-transplant donor specific antibodies (DSA) showed 5 of 9 patients diagnosed as C4d+ AMR displayed C1q positive DSA (P = 0.145). One out of 7 patients without AMR displayed C1q binding DSA. Conclusions Our data indicate that antibody strength correlates with the capacity to bind C1q (Fig. 1). However we identified a subset of antibodies that displayed high MFI values and CDC positivity, that failed to bind C1q. The development of C1q positive DSA was not significantly associated with positive C4d staining on the graft. Additional studies are required using a larger cohort of patients to verify these findings [Fig. 1]. Download : Download full-size image

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Aim Cross match (XM) results are highly predictable by single antigen bead (SAB) / Luminex technology when low or high levels of donor specific antibody (DSA) are present. However, about 5% of sera have DSA in an intermediate range where XM results are inconsistent therefore decreasing the reliability of the Virtual XM (VXM). In the following case reports we demonstrate a simple DSA analysis method for addressing this issue. Methods A DSA analysis method was developed where an MFI score (MFI-s) = Sum (minus background) of all positive DSA - bead - MFI, for each bead expressing the reactive DS epitope (EP). EP reactivity was determined by evaluation of SAB test data in conjunction with EP listings in published/online databases (see El-War, 2007 and the HLA EP Registry, http://epregistry.ufpi.br/index/index). If more than one DS EP (DSE) was detected all were included in the MFI-s. MFI-s of HLA class 1 DSE was used to predict the T cell FCXM whereas the MFI-s of HLA class 1 and class 2 DSE were added to predict the B cell FCXM since B cells express both antigens on their surface. Results When the highest MFI among multiple DSA allele beads (eg A*02:01 + B*07:01) is used to predict the VXM, then a positive T or B cell FCXM is observed in >90% of the cases when the latter summed MFI value is > 5,000. However in some patients, positive FCXM were observed with a representative-bead-MFI sum of only about 1000. This result occurred when the DSA was against an EP that was broadly distributed over a large number of antigens in the SAB assay. For such patients when all of the EP positive beads were summed the MFI-s was > 11,000. In the latter analyses a positive FCXM would be predicted. Conclusions False negative VXMs occurred in patients when the level of DSA was relatively low and importantly when the EP was broadly distributed over a large number of antigens represented in the SAB assay. The reliability of the VXM is improved when a DSA analysis method is used that calculates an MFI-s from DSE beads. Norin: Immucor - Lifescodes: Speakers Bureau.

Influence of preformed donor-specific antibodies and C4d on early liver allograft function

Introduction. The impact of preformed donor-specific antibodies (DSA) is incompletely understood in liver transplantation. The incidence and impact of preformed DSA on early post liver transplant were assessed and these were correlated with compliment fragment C4d on allograft biopsy. Methods. Pretransplant serum from 41 consecutive liver transplant recipients (brain dead donors; DBD = 27 and cardiac death donors; DCD = 14) were tested for class-specific anti-human leukocyte antigen (HLA) and compared against donor HLA types. Liver biopsies were taken during cold storage (t-1) and post-reperfusion (t0) stained with C4d and graded for preservation-reperfusion injury (PRI). Results. Of the 41 recipients, 8 (20%) had anti-HLA class I/II antibodies pretransplant, 3 (7%) were confirmed preformed DSA; classes I and II (n=1) and class I only (n=2). No biopsies showed definite evidence of antibody-mediated rejection. Graft biopsies in overall showed only mild PRI with ischemic hepatocyte C4d pattern similar in both positive and negative DSA patients. One DSA-positive (33%) compared with four DSA-negative patients (10%) had significant early graft dysfunction; severe PRI causing graft loss from primary nonfunction was seen only in DSA-negative group. Allograft biopsy of preformed DSA-positive patient demonstrated only minimal PRI; however, no identifiable cause could be attributed to graft dysfunction other than preformed DSA. Conclusion. Preformed DSA are present in 5–10% liver transplant recipients. There is no association between anti-HLA DSA and PRI and C4d, but preformed DSA may cause early morbidity. Larger studies on the impact of DSA with optimization of C4d techniques are required.

Frequent development of subclinical chronic antibody-mediated rejection within 1year after renal transplantation with pre-transplant positive donor-specific antibodies and negative CDC crossmatches

Although short-term graft survival has been improved by recent desensitization protocols including B cell depletion therapy, little is known about risk factors of chronic antibody-mediated rejection (CAMR) in HLA-incompatible (HLA-I) renal transplantation (RTx). Twenty-six HLA-I RTx with positive donor-specific antibodies (DSA) and negative T cell cytotoxic crossmatches were compared with 88 ABO-incompatible (ABO-I) and 207 ABO-identical/compatible (ABO-Id/C) RTx. The desensitization therapy consisted of mycophenolate mofetil, rituximab and double-filtration plasmapheresis. Protocol biopsies within 1 year revealed subclinical CAMR in 36% of HLA-I, 5% of ABO-I and 3% of ABO-Id/C, although clinical acute AMR was observed in 8%, 3% and 1%, respectively. The incidence of CAMR was not different between class I and class II DSA. Most of class I DSA (94%) changed to negative 1 year after RTx, whereas 77% of class II DSA remained positive. In addition, the remaining DRB ± DQB DSA caused CAMR in 80% of patients, while DQB DSA alone did not. The progress of subclinical CAMR within 1 year could not be circumvented by rituximab. Sustained class II (DRB ± DQB) DSA detection after RTx may pose a potential risk for developing CAMR, but negative change in class I DSA could also elicit CAMR.

A Survey of Current Practice for Antibody-Mediated Rejection in Heart Transplantation

No evidence based management guidelines exist for antibody mediated rejection (AMR) in heart transplantation. The International Society for Heart and Lung Transplantation (ISHLT) recently introduced standardized pathologic based diagnostic criteria for AMR (pAMR 0-3). We evaluated international practice for the management of AMR focusing on pAMR grade, donor specific antibody (DSA) and allograft function. On-line survey data were analyzed from 184 ISHLT members (physicians-78%, surgeons-20%). The majority were from adult-transplant (84%), medium-large volume centres (transplants/year: 10-25, 61%; 25-50, 19%) across North America (60%) and Europe (26%). Irrespective of pAMR grade and DSA, 83-90% treated a drop in ejection fraction (EF≤45% or >25% decrease). In the presence of stable EF, an increasing number elected treatment for progressively severe pAMR grade (p<0.001) and for accompanying DSA (p<0.05, pAMR 1-3). Intravenous steroid was the most commonly used therapy followed by intravenous immunoglobulin (IVIG) or plasmapheresis, rituximab and thymoglobulin. Plasmapheresis and rituximab were favored for positive versus negative DSA (p<0.05). Using a threshold of ≥70% consensus among respondents, treatment for AMR may be considered for a drop in EF, asymptomatic pAMR 3 or asymptomatic pAMR 2 with DSA. Combination steroid, IVIG and plasmapheresis are suggested as initial therapies.

Histological Characterization of Pulmonary Transplant Patients with Donor Specific Antibodies and Those without

Purpose Allogeneic antibodies to HLA antigens are implicated in the pathogenesis of antibody mediated rejection (AMR). We compared the frequency and class of panel reactive antibodies (PRAs) and donor specific antibodies (DSAs) with histologic features of rejection in a series of lung transplant patients. Methods and Materials We prospectively graded cellular rejection (CR) by ISHLT criteria in a series of transbronchial biopsies. The presence of alveolar septal macrophages and neutrophils was assessed separately, as well as intra-alveolar fibrin and hemosiderin laden macrophages. Immunohistochemical staining against C4d, C3d, and CD68 was performed in all cases. We retrospectively compared these findings with HLA serology as assayed by single antigen and multiple antigens Luminex ® beads. PRA was considered significant if positivity is >20%. DSA was considered positive if the mean fluorescence index is >1000. Results There were 509 biopsies from 89 patients, 54 men (62 ± 13 years) and 35 women (59 ± 13 years). There were 36 patients with at least one episode of CR. There was no correlation between CR and PRA to HLA class I antigens. PRA to HLA class II antigens were seen more frequently in patients with ≥1 biopsy with CR (p = .06). Patients with positive DSAs were more likely to have an episode of CR (p=.001), and the rate was highest in patients with combined A and B rejection, and with antibodies to HLA class II (DQ and DR) antigens. 7 patients had ≥ 1 biopsy with intracapillary macrophages with or without neutrophils; 5 of these had DSA, compared to 21 of 81 patients without (p = .02). There was no correlation between intra-alveolar fibrin, hemosiderin, or positivity with complement by immunohistochemistry with PRA or DSA (all p > 0.3). Conclusions Alloantibodies with donor specificity, especially against HLA class II antigens, are more frequent in patients with cellular rejection and intracapillary macrophages with or without neutrophils.

Perioperative Therapeutic Plasmapheresis

Perioperative Therapeutic Plasmapheresis

Significance of Semiquantitative Assessment of Preformed Donor-Specific Antibody Using Luminex Single Bead Assay in Living Related Liver Transplantation

Aim. To analyze the risks of preoperatively produced donor-specific antibody (DSA) in liver transplantation. Methods. DSA was assessed using direct complement-dependent cytotoxicity (CDC) and anti-human globulin- (AHG-) CDC tests, as well as the Luminex Single Antigen assay. Among 616 patients undergoing blood type identical or compatible living donor liver transplantation (LDLT), 21 patients were positive for CDC or AHG-CDC tests, and the preserved serum from 18 patients was examined to determine targeted Class I and II antigens. The relationships between the mean fluorescence intensity (MFI) of DSA and the clinical outcomes were analyzed. Results. Patients were divided into 3 groups according to the MFI of anti-Class I DSA: high (11 patients with MFI > 10,000), low (2 patients with MFI < 10,000), and negative (5 patients) MFI groups. Six of 11 patients with high Class-I DSA showed positive Class-II DSA. Hospital death occurred in 7 patients of the high MFI group. High MFI was a significant risk factor for mortality (P = 0.0155). Univariate analysis showed a significant correlation between MFI strength and C4d deposition (P = 0.0498). Conclusions. HLA Class I DSA with MFI > 10,000 had a significant negative effect on the clinical outcome of patients with preformed DSA in LDLT.

Diagnosis and treatment of antibody mediated rejection in lung transplantation: A retrospective case series

IntroductionAntibody mediated rejection (AMR) has been identified as an entity that may lead to graft dysfunction. Optimal means for diagnosis and treatment of AMR have not been established. Material and methodsWe reviewed the medical records of all patients receiving lung transplantation at Henry Ford Hospital from March 2006 to December 2011. For each patient, we identified potential markers of AMR (immunopathology, histopathology, and serology). Immunopathology was defined as linear c4d immunostaining, histopathology was defined as capillaritis, and serology was defined as identification of donor specific antibody (DSA). We identified all treatment regimens, and we identified clinical and serological outcomes. ResultsOf 62 patients, 14 were identified with at least one marker of AMR. Only two patients had all three potential markers; immunopathology, histopathology, and serology. Both patients received plasmapheresis (PP) and intravenous immunoglobulin followed by clinical improvement and ultimate elimination of DSA. 4 patients had positive DSA without clinical symptoms, and did not receive treatment with PP, IVIG, or rituximab. DSA has not persisted in these patients, and they remain clinically asymptomatic at up to 803days after identification. DiscussionDiagnosis of AMR is difficult due to poorly defined diagnostic markers and confounding factors such as infection. Outcomes are highly variable following treatment that may include therapeutic plasma exchange, intravenous immunoglobulin, and/or rituximab. It is not clear when any or all of these therapies are beneficial. In some cases, symptomatic patients with isolated positive DSA (latent humoral response) can remain asymptomatic and convert to negative DSA without antibody targeted therapy. ConclusionsFirm conclusions are difficult due to the small number of patients and the retrospective nature of the study. Further study is warranted.

Treatment of Antibody-Mediated Rejection in Kidney Transplant Recipients: A Single-Center Experience With a Bortezomib-Based Regimen

Antibody-mediated rejection after kidney transplant is less responsive to conventional antirejection therapies. The proteasome inhibitor bortezomib has activity against mature plasma cells that produce damaging donor-specific antibodies. We present our experience of using a bortezomib-based regimen in patients with severe antibody-mediated rejection. A retrospective chart review was performed on patients with biopsy-proven antibody-mediated rejection after kidney transplant at our institution over 12 months. Diagnosis of antibody-mediated rejection was made on the basis of positive peritubular capillary C4d staining along with either histologic evidence of acute rejection or positive donor-specific antibody titers. Treatment for antibody-mediated rejection included plasmapheresis, intravenous immunoglobulin, steroids, single-dose rituximab (375 mg/m²) along with bortezomib (1.3 mg/m²) on days 1, 4, 8, and 11. Antibody-mediated rejection was diagnosed in 6 patients. Patients received induction with either alemtuzumab (n=4) or rabbit-antithymocyte globulin (n=2) and were maintained on a tacrolimus/mycophenolate mofetil/early steroid withdrawal protocol. Four of 6 patients responded to treatment. Patients had stable kidney function during followup (median 14 months) after bortezomib therapy. In this series, we demonstrated the effectiveness of a bortezomib-based treatment regimen in achieving reduction of donor-specific antibody titers and stable renal function in patients experiencing severe antibody-mediated rejection.

Outcome of Desensitization in HLA and ABO Incompatible Living Donor Kidney Transplantation: A Single Center Experience of More than 100 Patients

Introduction: Antibody mediated rejection (AMR) and inferior graft outcome remain the two most important obstacles to successful kidney transplantation in HLA and ABO incompatible recipients. We report a single center experience in the outcome of desensitized living donor HLA and ABO incompatible kidney transplantation. Methods: Since 2007, we included all HLA incompatible living donor kidney transplant candidates with T cell IgG AHG CDC crossmatch (CXM) titer of £1:8 and all ABO incompatible living donor kidney transplant candidates with IgM isoagglutinins titer of £ 256 in our desensitization program. All candidates were risk stratified for AMR and were subjected to an individualized desensitization protocols as follows: ABO incompatible and HLA incompatible candidates with positive AHG CDC CXM and positive donor specific antibody (DSA) by solid phase immunoassay (SPI) were deemed as high risk and received single dose Rituximab®, therapeutic plasma exchange (TPE) and high dose IVIG (2 gm/kg of body weight). HLA incompatible candidates with negative CDC and positive T and/or B IgG flow CXM and positive DSA by SPI were deemed as intermediate risk and received Rituximab® and high dose IVIG. HLA incompatible candidates with negative CDC and flow CXM and positive DSA by SPI were deemed as low risk and received small dose IVIG (1 gm/kg body weight). At transplant, all patients received induction with Thymoglobulin® and were maintained on Tacrolimus based immunosuppressive regimen. Results: There were 108 incompatible recipients; 33 received ABO incompatible and 75 received HLA incompatible living donor kidney transplantation after desensitization. Risk stratification for HLA incompatible transplant revealed 24 patients as high risk, 34 as intermediate risk, and 17 as low risk. 57 (53%) of the study population were females; average age was 43 (range: 15-83) years; 15 (14%) received pre-emptive kidney transplantation and 85 (79%) were primary transplants. Over a median follow up of 652 (range: 8-1444) days, patient survival was 98% and death censored graft survival was 96%. Average serum creatinine was 85 (32-160) mmol/L. Clinical and subclinical ACR was observed in 14 (13%) patients and clinical and subclinical AMR in 4 (3.7%) patients. All rejection episodes responded to treatment except one AMR in ABO incompatible transplant which led to graft failure. Conclusion: Within our inclusion criteria, risk stratification scheme and desensitization strategy, the short and intermediate outcome of HLA and ABO incompatible living donor kidney transplantation appears not to be different from those reported in HLA and ABO compatible transplantation. These excellent results are likely to positively impact the long term outcome.

Antibody Mediated Rejection in a Living Donor Kidney Transplant Programme

Background: Acute rejection (AR) after transplant is associated with significant reduction in graft half life. With advent of newer immunosuppressive drugs, the incidence of acute rejection has decreased worldwide, but antibody mediated rejection (AMR) remains an important cause of graft loss. We analyzed spectrum of acute AMR and their short term outcomes at our centre. Methods: We analyzed 264 patients, transplanted between Feb 2010 and Oct 2011 who had at least 3 months of follow up. Immunosuppressive protocols were- TAC+MMF+ST in 169/264 (64%) patients, steroid free (SF) protocol (Induction+TAC+MMF) in 76/264 (29%), TAC+AZA+ST in 16/264 (6%) and CYC+MMF+ST in 3 (1.2%) patients with HCV infection. In SF group, 4/76 received ATG induction and rest received basiliximab as induction. In steroid group 63/187 (23.8%) patients received basiliximab induction and 8 patients who were second or third transplant (1 patient) received ATG as induction. NIH CDC cross match was negative in all patients prior to transplantation. Tacrolimus levels were done routinely and graft biopsy was done whenever rejection was suspected. The AMR was defined according to Banff 97 classification, i.e.- presense of 2/3 criteia-.presense of donor specific antibody (DSA), C4d positivity on IF and light microscopic features of AMR. Target trough level of tacrolimus was kept between 8-12 ng/ml for first three months, 6-8 ng/ml for next 3-6 months and 4-6 ng/ml thereafter. Outcomes were evaluated in terms of acute rejection, reversal of rejection with treatment and graft or patient loss. Results: 203/264 patients (76.8%) were males. The mean age was 40.5 (±13) years. The mean duration of follow up was 290 (±110.) days. 36/264 (13.6%) developed AR, of which 31/36 (86%) were biopsy proven (BPAR). 7/264 (2.6%) had AMR (22.5% of BPAR), 6 of these were in steroid group, 5 of them developed rejection within 4-5 days and they received thymoglobulin, plasmapheresis (PP), and intravenous immunoglobulins(IV Ig), however graft nephrectomy had to be done in 3/5 as they did not respond and there was infarction in grafts on repeat biopsy. Two patients responded completely. Two of these patients had positive DSA after transplant. However one of them later on developed chronic AMR. The sixth patient in steroid group had AMR at 7 months and had incomplete response. The only patient in steroid free group developed rejection 6 months after transplant and responded completely with same regimen. This patient later on developed chest infection and died. In three patients with graft nephrectomy, one patient received multiple blood transfusions, one patient had SLE and third patient had historic B cell cross match positivity. Overall graft survival was 96.2% and patient survival was 98.1%. Conclusions: AMR remains an important cause of resistant rejections and graft loss. More sensitive cross match tecniques might help to identify the high risk patients.

Improved Renal Function and Less Neurotoxicity in Kidney-Transplanted Children with Low Levels of Imtor and Tacrolimus without Steroids

Background: In kidney-transplanted children immunosuppressive regimens without tacrolimus are risky and hazardous without an assessment of T-memory cells, because are inhibited only by anticalcineurinic drugs. Combination of low levels of imTOR and tacrolimus without steroids could avoid nephro and neurotoxicity. Also imTOR could promote tolerance through FOX P3 expansion. A combination of advantages would be tried, versus a more classical approach. Patients and methods: Observational study of 62 kidney transplanted children, follow-up of 50±8 months. At the transplant all patients received tacrolimus, sodium mycophenolate and steroids. At the 6th month steroids were withdrawn in all patients. In group I, 42 patients were exposed in this moment to reduced levels of tacrolimus and imTOR (28 everolimus and 14 sirolimus), for a mean blood levels of 4-5 ng/ml for both. In group II, 20 patients were exposed to habitual levels of tacrolimus (8-11 ng/ml) and sodium mycophenolate. Results: – After 1 year Group I showed lower serum creatinine (0,8±0.2 vs. 1.2±0.6 mg/dL) and lower diastolic blood pressure (74±9 vs. 90±11 mm Hg). – No differences in proteinuria were found. In more than 90% of all patients, proteinuria was less than 0,5g/day, and in 70% was negative. – In group II, 4 patients (20%) presented intentional distal tremor in hands, that disappeared when received the regime of Group I, with improvement also of the kidney function. No tremor was registered in Group I. – No acute cellular rejections occurred during the follow-up. Chronic humoral rejection (positive donor-specific antibodies plus biopsy-proved diagnostic) was detected in two patients, one of each group. Conclusion: Combination of low doses of imTOR and tacrolimus, may offer a better renal function and blood pressure and less neurotoxicity without a higher incidence of proteinuria or rejection in kidney-transplanted children.

Successful Combined Liver and Kidney Transplant with Positive Flow Crossmatch and Multiple High Donor Specific Antibody Levels

Successful Combined Liver and Kidney Transplant with Positive Flow Crossmatch and Multiple High Donor Specific Antibody Levels