Novo Donor-specific HLA Antibodies Research Articles

Early CYP3A5 Genotype-Based Adjustment of Tacrolimus Dosage Reduces Risk of De Novo Donor-Specific HLA Antibodies and Rejection among CYP3A5-Expressing Renal Transplant Patients.

Our previous retrospective single-center cohort study found, at 3-year follow-up, a trend toward low tacrolimus trough levels and an increased risk of de novo donor-specific anti-HLA antibodies (DSAs) and of antibody-mediated rejection (ABMR) in CYP3A5-expressing patients. Determining CYP3A5-expression status immediately after renal transplant would allow early genotype-based dosage adjustment of tacrolimus and might prevent the occurrence of de novo DSAs and ABMR, improving transplant outcome. 160 renal allograft recipients who underwent renal transplant at the University Hospital Essen between May 2019 and May 2022 were genotyped for the CYP3A5 rs776746 polymorphism within the first two weeks after transplant, and genotype-based dose adjustment of tacrolimus was performed for the follow-up of 2 years. CYP3A5 expression was detected in 33 (21%) of the 160 patients. Tacrolimus trough levels were similar in CYP3A5 expressers and nonexpressers over the entire 2-year follow-up period. However, we observed a trend toward slightly higher tacrolimus trough levels in CYP3A5 expressers, who, as expected, required tacrolimus dosages twice as high as did nonexpressers during follow-up. Calcineurin inhibitor (CNI) nephrotoxicity-free survival rates were comparable between CYP3A5 expressers and nonexpressers (p = 0.49). Rejection-free survival rates (p = 0.89), de novo anti-HLA antibody-free survival rates (p = 0.57) and de novo DSA-free survival rates (p = 0.61) did not differ between the two groups. Early detection of CYP3A5-expression status and resultant genotype-based adjustment of tacrolimus dosage after renal transplant protected patients from transplant rejection and de novo DSA formation and was not associated with increased incidence of CNI toxicity among CYP3A5 expressers.

Solid-Phase C1q/C3d Fixing Readouts Correlate with High Median Fluorescence Intensity (MFI) De Novo Donor-Specific HLA Antibodies and C4d⁺ Antibody-Mediated Rejection in Kidney Transplant Recipients.

BackgroundSolid-phase assays to investigate the complement-activating capacity of HLA antibodies have been utilized to optimize organ allocation and improve transplant outcomes. The clinical utility of C1q/C3d-binding characteristics of de novo donor-specific anti-HLA antibodies (dnDSA) associated with C4d-positive antibody-mediated rejection (C4d+ AMR) in kidney transplants (KTx) has not been defined.Material/MethodsSera from 120 KTx recipients that had dnDSA concurrent with protocol/cause biopsy (median 3.8 years after transplantation) were screened for C1q and C3d-binding dnDSA. The difference in the incidence of C4d+ AMR between recipients with and without C1q/C3d-binding dnDSA was assessed.ResultsOver 86% of dnDSAs were class II antibodies. The immunodominant dnDSAs characterized by the highest median fluorescence intensity (MFI) in most recipients were HLA-DQ antibodies (67%). Most recipients (62%, n=74) had either C1q+ (56%), C3d+ (48%), or both C1q+C3d+ (41.2%) dnDSA, while the remaining 38% were negative for both C1q and C3d. Of those with C1q+/C3d+ dnDSA, 87% had high-MFI IgG (MFI=14144±5363 and 13932±5278, respectively), while 65% of C1q−C3d− dnDSA had low-MFI IgG (MFI=5970±3347). The incidence of C4d+ AMR was significantly higher in recipients with C1q+ (66%), C3d+ (74%), and C1q+C3d+ (72%) dnDSA than in those with C1q−C3d− dnDSA (30%) recipients. Recipients with C3d+/C1q+ dnDSA had higher C4d+ scores on biopsy.ConclusionsC1q+/C3d+ dnDSA were associated with C4d+ AMR and high-IgG MFI. Our data call into question the predictive utility of C1q/C3d-binding assays in identifying KTx recipients at risk of allograft failure. In conclusion, IgG MFI is sufficient for clinical management, and the C1q/C3d-assays with added cost do not provide any additional information.

Development of De Novo Donor-specific HLA Antibodies and AMR in Renal Transplant Patients Depends on CYP3A5 Genotype.

Background.The single-nucleotide polymorphism CYP3A5 rs776746 is related to a reduction in the metabolizing activity of the CYP3A5 enzyme. People carrying at least one copy of the wild-type allele, defined as CYP3A5 expressers, exhibit higher clearance and lower trough concentrations of tacrolimus than homozygous nonexpressers, and this difference may affect alloimmunization and allograft function.Methods.We retrospectively studied 400 kidney transplant recipients treated with a tacrolimus-based immunosuppression regimen to detect CYP3A5 genotype, de novo formation of HLA antibodies and donor-specific antibodies (DSAs), and clinical outcome up to 5 y after transplant.Results.We found that 69 (17%) of the 400 patients were CYP3A5 expressers. During the first 3 y after transplant, CYP3A5 expressers tended to have lower tacrolimus trough levels than nonexpressers, although their tacrolimus dosage was as much as 80% higher. De novo DSAs were found more frequently in CYP3A5 expressers than in nonexpressers (13/69 [19%] versus 33/331 [10%], P = 0.02). De novo DSA-free survival rates (P = 0.02) were significantly lower for expressers than for nonexpressers. CYP3A5 genotype had no effect on allograft failure, but CYP3A5 expressers exhibited a significantly higher frequency of antibody-mediated rejection. CYP3A5 expresser status was an independent risk factor for the development of de novo DSAs (relative risk, 2.34, P = 0.01).Conclusions.Early detection of CYP3A5 expressers, enabling genotype-based dose adjustment of tacrolimus immediately after renal transplant, may be a useful strategy for reducing the risk of de novo DSA production and antibody-mediated rejection.

CLINICAL SIGNIFICANCE OF PRETRANSPLANT DONOR-SPECIFIC HLA ANTIBODIES IN KIDNEY TRANSPLANT RECIPIENTS OF HISPANIC POPULATION

Introduction: Donor-specific HLA antibodies (DSA) before kidney transplantation (KT) is one of the major risk factors for humoral rejection and lower graft survival (1-2). In order to identify prognostic factors and develop follow up strategies in this high risk population, it is required for transplant center to share their outcome data (3-4). In addition, in most previous studies the Hispanic population is poorly represented. Materials and Methods: Retrospective cohort and comparative study in KT recipients with pretransplant DSA measured by Luminex, negative AHG-CDC-XM (living and deceased donor) and negative flow cross match (living donor). Our main objective was to determine graft survival and describe the incidence of acute rejection (AR) and renal function (eGFR by CKD-EPI). Results: Between September 2006 and March 2017, 411 patients received KT in the INCMNSZ, 60 were identified with pretransplant DSA and compared with 60 KT recipients without pretransplant DSA, paired by donor type, induction and maintenance immunosuppression. Median age was 33 (range 27-44) years, 55 (45%) were women, 55 (45.8%) had unknown etiology of ESRD, months on dialysis [24 (range 12-48)], 10.7% received second KT, 63.3% were living donor receptor, 75% had thymoglobulin induction, 96% were with tacrolimus, mycofenolate mofetil and steroids as maintenance immunosupression. The incidence of AR was increased in the pretransplant DSA group (35.5% vs. 15.2%, p=0.011) and the median time between KT and AR episodes was lower in the pretransplant DSA group [12.8 (8.3-23.6) vs 32.1 (25.9-40.6), (p<0.0001)] months.In the pretransplant DSA group 52.4% of the biopsies with AR were protocol biopsies and 29% were secondary to graft disfunction.Incidence of De Novo DSA were similar between groups [30 (53.6%) vs 29 (56.8%), (p=0.732)].After 37.4 (range 29.2-52.3) months of follow up, eGFR was similar between groups 65.0 ± 22.0 vs 69.8 ± 21.4 ml/min/1.73m2 (p=0.19) and there were no difference in graft survival (87.7% vs 96.7% p=0.240) between pretransplant DSA and without pretransplant DSA groups, respectively.Discussion and conclusions: Although there is a higher incidence of rejection, KT recipients with pretransplant DSA could be considered candidates for KT. One limitation of this study is the small sample size and short follow-up time. However, we acknowledge that in this population of high immunological risk, induction therapy with lymphocyte depletors and powerful maintenance immunosuppression, combined with follow-up strategies as protocol biopsies with early treatment of subclinical rejection could provide similar graft survival compared to KT receptors without pretransplant DSA.

Mid-Term Outcomes After Treatment for Antibody-Mediated Rejection by De Novo Donor-Specific HLA Antibody in Renal Transplant Recipients: Does Early Treatment Lead to Better Outcomes?

BackgroundDe novo donor-specific HLA antibody (DSA) and antibody-mediated rejection (ABMR) are strongly associated with late allograft loss in renal transplant recipients. However, the impact of therapeutic intervention with the current treatment options for ABMR remains unclear. This study aimed to elucidate the efficacy of treatment for ABMR. MethodsSixty-seven patients who had de novo DSAs underwent diagnostic biopsy for ABMR, and these patients were classified into 3 groups: ABMR-free group (n = 40), clinical ABMR group (n = 15), and subclinical ABMR group (n = 12). The ABMR-positive groups were treated mainly with double-filtration plasmapheresis followed by rituximab and corticosteroid pulse. The patient characteristics and graft outcomes were compared between groups. ResultsThe clinical and subclinical ABMR groups were younger and had a higher number and mean fluorescence intensity (MFI) of de novo DSAs than the ABMR-free group. The graft survival in the clinical ABMR group was significantly lower than that in the ABMR-free group, but the subclinical ABMR group had a surprisingly good graft survival rate compared to the ABMR-free group (43.3% vs 100% vs 94.2% 5 years after diagnostic biopsy in the clinical ABMR, subclinical ABMR, and ABMR-free groups, respectively, P < .001). ConclusionsOur findings indicated that early therapeutic intervention for patients with de novo DSAs may improve graft survival.

Anti-perlecan antibodies and acute humoral rejection in hypersensitized patients without forbidden HLA specificities after kidney transplantation

BackgroundThe improvement in the definition of serum anti-HLA antibodies (HLA-Abs) profiles after Luminex-assay implementation in transplant patients follow-up is clear. This success has permitted the development of hypersensitized-recipient allocation and donor-paired exchange programs improving the access to transplantation. However, non-HLA Abs have been described in transplanted patients but their effect in hypersensitized transplanted recipients is unclear. MethodsTwenty-seven HLA hypersensitized patients awaiting for kidney transplantation (KT) were studied and 11 of them were followed after KT. The HLA Abs profile was confirmed in serum by Single Antigen Luminex assay and panel reactive of antigens >98% was achieved in all patients. Subsequently, the ability to fix complement by C1q test was also assessed. Serum non-HLA Abs before and 1 month after transplantation were measured in the 11 hypersensitized recipients. Results95.2% of the hypersensitized on waiting list had concomitant serum anti-HLA and non-HLA Abs. The more frequent specificity in non-HLA Abs were found against Glutathione S-transferase theta-1 (GSST-1) (in 62%) and C-terminal fragment of perlecan (LG3) (in 52%). Four out of 11 transplanted patients presented early antibody-mediated rejection (ABMR) confirmed by biopsy and had serum anti-LG3 antibodies, two of them with concomitant anti-anti-angiotensin II type I receptor. Only one patient developed de novo-donor specific HLA antibodies. ConclusionsThe incidence of non-HLA antibodies in patients in the waiting list is largely underestimated. The concomitance anti-HLA and non-HLA Abs in hypersensitized patients is very common and the detection of non-HLA Abs in this population could allow to identify patients with an increased risk of humoral rejection.

Clinical impact of complement (C1q, C3d) binding De Novo donor-specific HLA antibody in kidney transplant recipients.

IntroductionComplement binding activity of donor-specific HLA antibodies (DSA) has been suggested as a new tool to stratify immunologic risk in kidney transplantation (KT). The objective of this study was to evaluate the clinical implication of C1q/C3d binding activity of de novo DSA (dnDSA) in KT recipients.Material and methodsA total of 161 pretransplant DSA-negative recipients were monitored for dnDSA at the time of biopsy. C1q/C3d binding activities of dnDSA were assessed using C1qScreen assay (One lambda, USA) and Lifecodes C3d detection assay (Immucor, USA), respectively. Clinical outcomes including biopsy-proven antibody mediated rejection (AMR), C4d detection and post-biopsy graft survival were investigated.ResultsDe-novo DSAs were detected in fifty-four (33.5%) patients (HLA class I only, n = 19; class II only, n = 29; both class I and II, n = 6). Of them, complement binding activities were detected in 26 (48.1%) patients, including 17 C1q+ and 24 C3d+ patients. Both C1q and C3d positivity were associated with increased mean fluorescence intensity values of dnDSA. Complement binding activity of dnDSA enhanced the incidence of AMR (25.0% in C1q-C3d-, 36.4% in C1q+/C3d- or C1q-/C3d+, and 60.0% in C1q+/C3d+ patients) (P <0.001). The incidence of AMR was not different between patients with C1q+ and those with C3d+ dnDSA (64.7%, 11/17 versus 45.8%, 11/24, P = 0.238). In comparison between C1q and C3d assay according to HLA specificity, C1q+ HLA class I ± II dnDSA was the best predictor for AMR (odds ratio: 27.2). C1q+/C3d+ dnDSA was associated with more C4d deposition in allograft tissue and inferior post-biopsy graft survival. Clinical outcomes were not significantly different between C1q+ and C3d+ dnDSA-positive patients.ConclusionDetection of complement binding activity using both C1q and C3d assays can be a further prognostic marker for predicting AMR and allograft outcome in dnDSA+ kidney transplant patients.

Effect of Steroid Withdrawal on the Appearance of De Novo Donor-Specific HLA Antibodies in Kidney Transplant Recipients

Effect of Steroid Withdrawal on the Appearance of De Novo Donor-Specific HLA Antibodies in Kidney Transplant Recipients

Immunosuppression Related to De Novo Donor-Specific HLA Antibody Production after Renal Transplantation

Aim One of the major factors influencing graft loss is antibody-mediated rejection caused by the production of donor-specific HLA antibodies (DSA). The optimization of multidrug combination therapy using immunosuppressants is required in order to prevent DSA production. We herein evaluated the relationships among clinical variants including immunosuppressant levels and the prediction of DSA production after renal transplantation (Tx). Methods Living renal transplant patients (n=160) at our institute who received standard immunosuppressant protocols with basiliximab, tacrolimus (Tac), mycophenolate mofetil (MMF), and steroids between July 2004 and September 2013 were enrolled. The production of serum anti-HLA antibodies at one-year post-Tx was analyzed by solid-phase bead-based assays using Luminex. The HLA specificity of DSA was evaluated based on the data of donor HLA typing. In the present study, preformed DSA and de novo DSA were defined as those detected pre-Tx and at one-year post-Tx, and those detected at one-year post-Tx only, respectively. Risk factors for DSA production were statistically evaluated using clinical variables including Tac trough levels and the incidence of virus infections. Results DSA production at one-year post-Tx was observed in 15 patients including 9 with preformed DSA and 7 with de novo DSA. Preformed and de novo DSA were detected in one patient. De novo DSA production was more likely to occur in patients with low serum Tac levels (cut-off value: 3.2 ng/mL), in those who ceased MMF medication, and in those who acquired CMV infection within one-year post-Tx (p=0.008, 0.044, and 0.050, respectively). Conclusions The appropriate control of Tac trough levels, continuation of MMF intake, and prevention of CMV infection were found to be important for avoiding de novo DSA production at one-year post-Tx in the present study.

Elevated Donor-Derived Cell-Free DNA (ddcfDNA) as an Early Risk Factor for the Development and Persistence of De Novo Donor Specific HLA Antibody

We have previously shown that elevations in total donor derived cell free DNA (%ddcfDNA) correlate with graft injury and failure following lung transplantation. The incidence of antibody mediated rejection (AMR) was higher for lung transplant recipients with early elevations of ddcfDNA, leading us to hypothesize that early elevations of ddcfDNA may be a risk factor de novo DSA. In this current study, we will examine the utility of early %ddcfdDNA measurements as an independent variable to predict de novo donor specific HLA antibody (DSA) development in lung transplant recipients. Furthermore, we will determine if a composite analysis of DSA strength and %ddcfdDNA levels can better predict the efficacy of therapeutic intervention to reduce or eliminate de novo DSA.

Donor-Recipient Matching Based on Predicted Indirectly Recognizable HLA Epitopes Independently Predicts the Incidence of De Novo Donor-Specific HLA Antibodies Following Renal Transplantation.

De novo donor-specific HLA antibodies (dnDSA) are recognized as a risk factor for premature allograft failure. Determinants of DSA specificity are generated via the indirect allorecognition pathway. Here, we present supportive data for the relevance of predicted indirectly recognizable HLA epitopes (PIRCHE) to predict dnDSA following kidney transplantation. A total of 2787 consecutive kidney transplants performed between 1995 and 2015 without preformed DSA have been analyzed. De novo DSA were detected by single antigen bead assay. HLA epitope mismatches were determined by the HLAMatchmaker and PIRCHE approach and correlated in uni- and multivariate analyses with 10-year allograft survival and incidence of dnDSA. The PIRCHE-II score moderately predicted allograft survival. However, the predictive value of elevated PIRCHE-II scores >9 for the incidence of dnDSA was statistically significant (p < 0.001). In a multivariate Cox regression analysis adjusted for antigen mismatch and HLAMatchmaker epitopes, the PIRCHE-II score could be identified as an independent risk factor for dnDSA. The PIRCHE-II score independently from the antigen mismatch and HLAMatchmaker epitopes could be revealed as being a strong predictor for dnDSA. PIRCHE may help to identify acceptable mismatches with decreased risk of dnDSA and thus improve long-term renal allograft survival.

De Novo Donor-Specific HLA Antibodies Developing Early or Late after Transplant Are Associated with the Same Risk of Graft Damage and Loss in Nonsensitized Kidney Recipients.

De novo posttransplant donor-specific HLA-antibody (dnDSA) detection is now recognized as a tool to identify patients at risk for antibody-mediated rejection (AMR) and graft loss. It is still unclear whether the time interval from transplant to DSA occurrence influences graft damage. Utilizing sera collected longitudinally, we evaluated 114 consecutive primary pediatric kidney recipients grafted between 2002 and 2013 for dnDSA occurrence by Luminex platform. dnDSAs occurred in 39 patients at a median time of 24.6 months. In 15 patients, dnDSAs developed within 1 year (early-onset group), while the other 24 seroconverted after the first posttransplant year (late-onset group). The two groups were comparable when considering patient- and transplant-related factors, as well as DSA biological properties, including C1q and C3d complement-binding ability. Only recipient age at transplant significantly differed in the two cohorts, with younger patients showing earlier dnDSA development. Late AMR was diagnosed in 47% of the early group and in 58% of the late group. Graft loss occurred in 3/15 (20%) and 4/24 (17%) patients in early- and late-onset groups, respectively (p = ns). In our pediatric kidney recipients, dnDSAs predict AMR and graft loss irrespective of the time elapsed between transplantation and antibody occurrence.

Kidney Intragraft Homing of De Novo Donor-Specific HLA Antibodies Is an Essential Step of Antibody-Mediated Damage but Not Per Se Predictive of Graft Loss.

Donor-specific HLA antibody (DSA)-mediated graft injury is the major cause of kidney loss. Among DSA characteristics, graft homing has been suggested as an indicator of severe tissue damage. We analyzed the role of de novo DSA (dnDSA) graft homing on kidney transplantation outcome. Graft biopsy specimens and parallel sera from 48 nonsensitized pediatric kidney recipients were analyzed. Serum samples and eluates from graft biopsy specimens were tested for the presence of dnDSAs with flow bead technology. Intragraft dnDSAs (gDSAs) were never detected in the absence of serum dnDSAs (sDSAs), whereas in the presence of sDSAs, gDSAs were demonstrated in 72% of biopsy specimens. A significantly higher homing capability was expressed by class II sDSAs endowed with high mean fluorescence intensity and C3d- and/or C1q-fixing properties. In patients with available sequential biopsy specimens, we detected gDSAs before the appearance of antibody-mediated rejection. In sDSA-positive patients, gDSA positivity did not allow stratification for antibody-mediated graft lesions and graft loss. However, a consistent detection of skewed unique DSA specificities was observed over time within the graft, likely responsible for the damage. Our results indicate that gDSAs could represent an instrumental tool to identify, among sDSAs, clinically relevant antibody specificities requiring monitoring and possibly guiding patient management.

The Influence of Immunosuppressive Agents on the Risk of De Novo Donor-Specific HLA Antibody Production in Solid Organ Transplant Recipients

Production of de novo donor-specific antibodies (dnDSA) is a major risk factor for acute and chronic antibody-mediated rejection and graft loss after all solid organ transplantation. In this article, we review the data available on the risk of individual immunosuppressive agents and their ability to prevent dnDSA production. Induction therapy with rabbit antithymocyte globulin may achieve a short-term decrease in dnDSA production in moderately sensitized patients. Rituximab induction may be beneficial in sensitized patients, and in abrogating rebound antibody response in patients undergoing desensitization or treatment for antibody-mediated rejection. Use of bortezomib for induction therapy in at-risk patients is of interest, but the benefits are unproven. In maintenance regimens, nonadherent and previously sensitized patients are not suitable for aggressive weaning protocols, particularly early calcineurin inhibitor withdrawal without lymphocyte-depleting induction. Early conversion to mammalian target of rapamycin inhibitor monotherapy has been reported to increase the risk of dnDSA formation, but a combination of mammalian target of rapamycin inhibitor and reduced-exposure calcineurin inhibitor does not appear to alter the risk. Early steroid therapy withdrawal in standard-risk patients after induction has no known dnDSA penalty. The available data do not demonstrate a consistent effect of mycophenolic acid on dnDSA production. Risk minimization for dnDSA requires monitoring of adherence, appropriate risk stratification, risk-based immunosuppression intensity, and prospective DSA surveillance.

C1q Binding Activity of De Novo Donor-specific HLA Antibodies in Renal Transplant Recipients With and Without Antibody-mediated Rejection.

Complement fixation by donor-specific HLA antibodies (DSA) is a primary mechanism for antibody-mediated damage of organ allografts. Using a recently developed kit that measures C1q binding to distinguish complement fixing and nonfixing antibodies, studies showed that C1q + DSAs have a higher risk of rejection and graft loss compared to C1q-DSA. The objective of this study was to assess the ability of the C1q-binding assay to identify clinically significant de novo DSA in renal transplant recipients and to define the properties of DSA that confer C1q binding ability. The DSA-positive sera from 34 kidney recipients, 19 with biopsy-proven antibody-mediated rejection (AMR) + and 15 who were AMR-, were assayed in C1q-binding assays (C1q Screen; One Lambda, Inc. Canoga Park, CA). The correlation between C1q-binding activity, presence of AMR, DSA mean fluorescence intensity (MFI) values, and immunoglobulin G isotype was determined. Fifty-three percent (10/19) of sera from AMR+ patients had C1q + DSA, whereas only 13% (2/15) of sera from AMR- patients contained C1q + DSA. C1q + DSA exhibited significantly higher MFI values regardless of whether they were from AMR+ or AMR- patients (16,118 ± 6698 vs 6429 ± 4003; P < 0.0001). C1q + DSA converted to C1q - when diluted to a comparable MFI level as the C1q - DSA from AMR- patients, and some C1q - antibodies converted to C1q + when concentrated to MFI levels comparable to those observed for AMR+/C1q + sera. The C1q binding activity by de novo DSA in patients with AMR largely reflects differences in antibody strength. The C1q assay does not appear to distinguish functionally distinct DSA with clinical significance.

(266) - IgM De Novo Donor Specific HLA Antibodies (dnDSA) Claws Switch to IgG and DQ dnDSA Are Associated With C4d+ Biopsies Conversion to C4d+/C3d+ and Progression of Subclinical Antibody Mediated Rejection in Heart Transplant Recipients

(266) - IgM De Novo Donor Specific HLA Antibodies (dnDSA) Claws Switch to IgG and DQ dnDSA Are Associated With C4d+ Biopsies Conversion to C4d+/C3d+ and Progression of Subclinical Antibody Mediated Rejection in Heart Transplant Recipients

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.

Histological Findings of Bronchial Biopsies and De Novo Donor Specific HLA Antibodies: Comparing Notes

Purpose De novo development of donor HLA specific antibodies (DSA) after lung transplantation has been implicated in acute and chronic rejection. However, the diagnostic criteria of antibody mediated rejection (AMR) in lung allografts remain unclear. In addition, the association between DSA and histological findings on lung biopsies is unclear. In this study we investigate the association between development of DSA and lung biopsy findings. Methods and Materials We retrospectively analyzed the records of 85 lung transplant recipients (53 males, 32 females, mean age at transplant 55.5, range 20-70) who had for-cause post-transplant monitoring for DSA performed using single antigen Luminex assay (One Lambda, Canoga Park, CA) within ±1 week of the a biopsy date (paired biopsies). Some patients had multiple paired biopsies (n=116). All recipients had protocol bronchial biopsies at 2 weeks, 1, 3, and 6 months, at 1 year and for cause thereafter. We attempted to correlate de novo DSA with the following histological findings: C4d staining, acute rejection ≥ISHLT grade 2A, acute lung injury (ALI), organizing pneumonia (OP). Results 25 patients developed de novo DSA (29%), of those 4 had HLA class I DSA, 18 had class II, and 3 had both class I and II. The average post-transplant day for detection of class I DSA was 166 (range: 6-528) and 296 for class II (range: 6-790). The distribution of histological findings in patients with and without DSA is shown in table 1 . In this cohort, we did not observe an appreciable difference in the mean graft survival among patients with and without DSA (600 vs. 606, respectively). Conclusions These data suggest that de novo DSA following lung transplant is significantly associated with acute rejection > ISHLT A2, and lesser degree with C4d but not ALI or OP and warrant further prospective investigation in larger cohorts. AR≥A2 C4d+ ALI OB All Bipsies, n=116 20, 17% 5, 4% 41, 35% 8, 7% DSA+, n=62 16, 26%, p .01 5, 8%, p .06 23, 37% 5, 8%, p .7 DSA-, n=54 4, 7% 0 18, 33%, p .7 3, 6%

Time from Development of De Novo Donor-Specific HLA Antibodies to Rejection or Graft Loss in Pediatric Cardiac Transplantation

Purpose There is increasing evidence that de novo donor-specific HLA antibodies (DSA) are associated with poor outcome following cardiac transplantation. Management of these remains problematic and there is little data on lag time from DSA development to an adverse event. We aimed to determine average time from first detection of DSA to rejection, cardiac allograft vasculopathy(CAV) or graft loss in a pediatric cohort. Methods and Materials Luminex screens and single antigen tests were performed on stored samples taken at 3, 6, 12 months and then annually in patients transplanted age Results 108 patients, mean age at transplant 7.4 (0.1-15.9) years were studied, mean follow-up 8.2 (1.9-15.7) years. All had a CDC-negative crossmatch and retrospective serum analysis confirmed they had no DSA prior to transplant. 43/108 (40%) patients had DSA with median time from transplant to DSA development of 2 (0.25-11) years. Freedom from DSA was 91% at 3 months, 86% at 6 months, 84% at 1 year, 69% at 5 years, 58% at 10 years and 48% at 15 years post-transplant. 9 patients with DSA (21%) developed CAV, and in 6 (67%), DSA were detected prior to CAV diagnosis with median lag time of 2.2 (1-4.9) years. 14 patients (33%) had a rejection episode, 9 (64%) had DSA prior to rejection with median lag time time of 2.8 (0.2-7.2) years. 10 patients (23%) died or were re-transplanted, with median time from development of DSA to graft loss of 1.7 (0.1-4.8) years. 28/33 (85%) patients with an adverse outcome had Class II DSA with anti-DQ the most prevalent. Conclusions In patients with DSA in whom an adverse event occurred (CAV, Rejection or Graft loss) DSA were detected in 25/33 (76%) prior to the adverse outcome. The majority of patients with an adverse outcome in this study had Class II DSA detected prior to that event. These findings suggest that once DSAs have developed increased surveillance for adverse events should be implemented.

Immunity to Polyomavirus BK Infection: Immune Monitoring to Regulate the Balance between Risk of BKV Nephropathy and Induction of Alloimmunity

Polyomavirus BK-associated nephropathy (PyVAN) is the main infectious cause of allograft damage after kidney transplantation. A number of studies revealed an association between the presence of BKV-specific cellular immunity and BK viral clearance, with patients failing to recover specific T cells progressing to PyVAN. Evolution to allograft dysfunction can be prevented by restoration of BKV-specific immunity through a stepwise reduction of maintenance immunosuppressive drugs. Prospective monitoring of BK viral load and specific immunity, together with B-cell alloimmune surveillance, may allow a targeted modification/reduction of immunosuppression, with the aim of obtaining viral clearance while preventing graft injury due to deposition of de novo donor-specific HLA antibodies and late/chronic antibody-mediated allograft injury. Innovative, immune-based therapies may further contribute to BKV infection prevention and control.