DSA-positive Patients Research Articles

The Significance of Screening for HLA Antibodies in the Long-Term Follow-up of Pediatric Liver Transplant Recipients

BackgroundPost-transplant donor-specific anti-HLA antibodies (DSA) reportedly have detrimental effects on the outcomes of organ transplantation. However, the prevalence of post-transplant DSA in the long term after pediatric liver transplantation remains unclear, and the significance of post-transplant DSA is unknown. The aim of this cross-sectional study was to determine the prevalence of and characteristics of patients with post-transplant DSA. Materials and MethodsOf the 84 pediatric liver transplant recipients who were followed up in the outpatient department of our institution, 34 patients with available HLA typing data were included after they or their parent(s) provided informed consent for DSA evaluations. Luminex single-antigen bead assays were performed, and a mean fluorescence intensity of ≥1000 was used as the cut-off for a positive reaction. ResultsNo class I DSA were detected, whereas class II DSA were detected in 11 patients (32%). There were no differences in age at transplantation, immunosuppressive drugs, or follow-up period between the DSA-positive and DSA-negative patients. The rate of positive pre-transplant complement-dependent cytotoxicity crossmatch was higher with class II DSA than without, although the difference was not statistically significant. ConclusionsThe utility of screening for class I DSA was insignificant in the long-term follow-up of pediatric liver transplant recipients. The prevalence of class II DSA was relatively high; therefore, screening for class II DSA might be justified, although a follow-up survey of the association between post-transplant class II DSA and the long-term clinical course needs to be conducted.

(557) - Clinical Implication of Non-Complement-Binding De Novo Donor-Specific Anti-HLA Antibodies in Heart Transplant Recipients: Do We Really Have to Care All the DSA Positive Patients?

(557) - Clinical Implication of Non-Complement-Binding De Novo Donor-Specific Anti-HLA Antibodies in Heart Transplant Recipients: Do We Really Have to Care All the DSA Positive Patients?

Association of C1q-fixing DSA with late graft failure in pediatric renal transplant recipients.

We investigated the prognostic value of overall and complement-binding donor-specific HLA antibodies (DSA) in pediatric patients undergoing clinically indicated graft biopsies and their association with graft outcome and specific histological lesions. Sera of 62 patients at time of indication biopsy ≥1year posttransplant were assessed for DSA and C1q-fixing DSA by single-antigen bead (SAB) technology. Twenty-six patients (42%) were DSA-positive at time of indication biopsy and nine (15%) were C1q-positive. At 4years postbiopsy, patients with C1q-positivity had a low graft survival (11%) compared to DSA-positive, C1q-negative patients (82%, p = 0.001) and to DSA-negative patients (88%, p < 0.001). The majority (89%) of C1q-positive patients were diagnosed with active chronic antibody-mediated rejection (ABMR). C1q DSA-positivity [adjusted hazard ratio (HR) 6.35], presence of transplant glomerulopathy (HR 9.54), and estimated glomerular filtration rate (eGFR) at the time of indication biopsy (HR 0.91) were risk factors for subsequent graft loss. The presence of C1q-positive DSA in the context of an indication biopsy identifies a subgroup of pediatric renal transplant recipients with a markedly increased risk of subsequent graft loss. Because a fraction of DSA-positive patients escape rejection or graft dysfunction, the C1q assay increases the specificity of a positive DSA result regarding unfavorable transplant outcome.

Donor-specific antibodies after pediatric liver transplantation: a cross-sectional study of 50 patients.

The role of donor-specific HLA antibodies (DSAs) after pediatric liver transplantation (LT) is inadequately established. We conducted a cross-sectional study on the prevalence of DSAs and their association with liver histology and biochemical variables after pediatric LT. Serum samples were drawn for HLA antibody analyses from 50 patients (76% of 66 eligible patients) operated on at age <18 years between 1987 and 2007 with a median of 10.0 (interquartile range 4.0-16.4) years after deceased donor LT. Mixed and single-antigen beads with Luminex were used for HLA antibody screening and detection. A mean fluorescence intensity (MFI) value of 1000 was used for positive cutoff. Twenty-six patients (52%; 95% confidence interval (CI) 39% to 65%) had DSAs. In 22 (85%) patients, DSAs were against class II HLA antigens with a mean (standard deviation) MFI of 13,481 (4727). The unadjusted prevalence ratio for portal inflammation in DSA-positive compared to DSA-negative patients (n = 47; 9/24 vs. 1/23) was 8.6 (95% CI 1.6 to 50.9). Laboratory values at the time of study were comparable between DSA-positive and DSA-negative patients. In conclusion, approximately half of patients studied had DSAs after pediatric LT. Portal inflammation was associated with DSA positivity although the wide confidence interval around the ratio estimate warrants cautious interpretation.

Immunological risk assessment: The key to individualized immunosuppression after kidney transplantation.

The wide range of immunosuppressive therapies and protocols permits tailored planning of the initial regimen according to the immunological risk status of individual patients. Pre-transplant risk assessment can include many factors, but there is no clear consensus on which parameters to take into account, and their relative importance. In general younger patients are known to be at higher risk for acute rejection, compounded by higher rates of non-adherence in adolescents. Donor age and recipient gender do not appear to exert a meaningful effect on risk of rejection per se, but black recipient ethnicity remains a well-established risk factor even under modern immunosuppression regimens. Little difference in risk is now observed between deceased- and living-donor recipients. Immunological risk assessment has developed substantially in recent years. Cross-match testing with cytotoxic analysis has long been supplemented by flow cytometry, but development of solid-phase single-bead antigen testing of solubilized human leukocyte antigens (HLA) to detect donor-specific antibodies (DSA) permits a far more nuanced stratification of immunological risk status, including the different classes and intensities of HLA antibodies Class I and/or II, including HLA-DSA. Immunologic risk evaluation is now often based on a combination of these tests, but other assessments are becoming more widely introduced, such as measurement of non-HLA antibodies against angiotensin type 1 (AT1) receptors or T-cell ELISPOT assay of alloantigen-specific donor. Targeted densensitization protocols can improve immunological risk, notably for DSA-positive patients with negative cytotoxicity and flow cross-match. HLA mismatch remains an important and undisputed risk factor for rejection. Delayed graft function also increases the risk of subsequent acute rejection, and the early regimen can be modified in such cases. Overall, there is a shift towards planning the immunosuppressive regimen based on pre-transplant immunology testing although certain conventional risk factors retain their importance.

Trends in the Management and Hospital Outcome of Spontaneous Subarachnoid Hemorrhage in the Post-International Subarachnoid Aneurysm Trial Era in Greece: Analysis of 719 Patients During a 13-Year Period

Management and outcome data on spontaneous subarachnoid hemorrhage (SAH) in Greece are scarce. We analyzed 13-year (2002-2014) retrospective data on all first-ever SAH patients referred to one of the largest neurosurgical academic departments. Patient demographic/clinical status, length-of-hospital stay, and hospital outcome were determined. Outcome in different treatment categories was compared and prognostic factors identified. A total of 719 patients were identified (mean age, 55 ± 12 years; men:women ratio, 1:1.4). Angiography (DSA) was performed in 88% of patients (N= 632); it was positive in 77.5% (N= 490). DSA was not performed in the remaining cases mainly due to early deaths (67 of 87; 77%). Of DSA-positive patients 74.9% (367 of 490; 51% of the total sample) underwent treatment. It comprised predominantly of coiling (81.5%) and to a lesser extent of clipping (18.5%). Lack of treatment on DSA-positive patients was largely due to early deaths (66 of 123; 53.7%). Favorable outcome was recorded in 45.6% overall (328 of 719). Favorable outcome or mean length of hospital stay did not differ significantly between coiling (51.2%; 24.7 ± 49 days) and clipping (48.8%; 28.8 ± 28 days). Nevertheless, the surgery group had a significantly higher proportion of dead patients. Advanced age and poor clinical presentation were independent risk factors for bad outcome. Predominance of coiling over time is consistent with current trends in Western Europe and the United States. Outcome of clipping or coiling was comparable to previous salient series. Early treatment/centralization of care remain prerequisites for extending treatment options and further improving SAH outcome.

Donor-specific HLA alloantibodies: Impact on cardiac allograft vasculopathy, rejection, and survival after pediatric heart transplantation

There is increasing evidence that donor-specific anti-HLA antibodies (DSA) are associated with poor outcomes after cardiac transplantation in adults, but data are limited in children. The objective of this study was to examine the development and consequences of de novo DSA in pediatric recipients of heart transplants. We analyzed 105 pediatric patients who received heart transplants at our center from January 2002 to December 2012. All patients had negative T-cell and B-cell post-transplant crossmatches. Patients underwent HLA antibody screening at 1, 2, 3, 6, and 12 months post-transplant and annually thereafter unless there was suspicion for rejection. HLA class I and II antibodies were identified using Luminex assay. Coronary angiography was performed at 1 year and annually thereafter. Acute cellular rejection, antibody-mediated rejection, and treated clinical rejections were included together as rejection events. Of 105 patients, 45 (43%) developed de novo DSA. DSA-positive patients had significantly higher rates of coronary artery vasculopathy (CAV) compared with DSA-negative patients (36% vs 13%). CAV-free survival at 1 year and 5 years post-transplant for DSA-negative patients was 90% and 25%, respectively, compared with 70% and 0%, respectively, for DSA-positive patients (p < 0.01). DSA-positive patients had 2.5 times more rejection events per year than DSA-negative patients. The 5-year graft survival rate was 72.4% for DSA-negative patients and 21% for DSA-positive patients (p < 0.001). De novo DSA has a strong negative impact on CAV, rejection, and graft survival in pediatric recipients of heart transplants.

Bronchiolitis obliterans syndrome due to donor-specific HLA-antibodies.

Chronic lung allograft dysfunction (CLAD) is a limiting factor for long-term survival in lung transplant recipients. Donor-specific human leukocyte antigen (HLA)-antibodies (DSA) have been suggested as potential risk factors for CLAD. However, their impact on clinical outcome following lung transplantation remains controversial. We performed a single-center study of 120 lung transplant recipients transplanted between 2006 and 2011. Patient sera were investigated before and after transplantation. The sera were screened by means of Luminex(®) technology (Luminex Inc., Austin, TX, USA) for IgG-HLA-class I and class II antibodies (ab). Using single antigen beads, DSA were identified and correlated retrospectively with clinical parameters. After transplantation 39 out of 120 patients (32.5%) were positive for HLA-ab. The incidence of de novo DSA formation was 27 of 120 patients (22.5%). Eleven of 27 (41%) of de novo DSA-positive patients developed BOS compared to 13 of 93 (14%) DSA-negative patients (p = 0.002). Furthermore, the generation of de novo DSA was independently associated with the development of BOS in multivariable analysis [hazard ration (HR) 2.5, 95% confidence interval (CI) 1.0-6.08; p = 0.046). Our results indicate that de novo DSA are associated with the development of BOS after lung transplantation. Monitoring of HLA-ab after transplantation is useful for identifying high-risk patients and offers an opportunity for early therapeutic intervention.

Donor-specific HLA Antibodies Are Associated With Late Allograft Dysfunction After Pediatric Liver Transplantation.

The role of donor-specific HLA antibodies (DSA) after pediatric liver transplantation (LTx) is not clearly established. We completed a cross-sectional study to characterize DSA in long-term survivors of pediatric LTx and assess the impact of C1q-binding DSA on allograft outcomes. Serum samples were collected at routine clinic visits from 50 pediatric LTx recipients classified into 3 clinical phenotypes: nontolerant (n = 18) with de novo autoimmune hepatitis (DAIH) and/or late acute cellular rejection (ACR); stable (n = 25) on maintenance tacrolimus; operationally tolerant (n = 7). Samples were blinded, and antibody detection was performed using Luminex single antigen class I and II beads. Patients with positive DSA were tested for C1q-binding DSA. DSA were detected in 54% (n = 27) of the patients, with the majority directed at HLA class II antigens (DR, 41%; DQ, 53%). Patients with DSA were younger at the time of LTx (P = 0.016) and time of study (P = 0.024). Mean aspartate aminotransferase, alanine aminotransferase, total bilirubin, and gamma glutamyl transferase were higher in DSA-positive patients, though did not reach statistical significance. Nontolerant patients were significantly more likely to have DQ DSA (61%) compared to stable (20%) and tolerant (29%) patients (P = 0.021). The nontolerant phenotype was associated with DSA and C1q-binding DSA, with odds ratios of 13 (P = 0.015) and 8.6 (P = 0.006), respectively. The presence of DQ DSA was associated with DAIH and late ACR, with odds ratios of 12.5 (P = 0.004) and 10.8 (P = 0.006), respectively. Allograft dysfunction is not always evident in patients with DSA, but DQ DSA are strongly associated with DAIH, late ACR, and chronic rejection.

Influence of de novo donor-specific antibody on early renal allograft function recovery

Background: The aim of the present study is to investigate the impact of de novo donor-specific antibodies (dnDSA) on early graft function, to provide objective reference for early clinical diagnosis and reasonable individualized treatment. Methods: 305 cases of renal transplant patients for the first time were observed in this study. Follow-up time for all recipients was 6 months after operation. HLA antibody, DSA, renal function were monitored after transplant. Results: In total of 305 cases, 66 cases (21.64%) were HLA antibody positive and 21 cases (6.89%) showed acute rejection (AR) in 6 months after transplant. The HLA antibody-positive patients included six cases of dnDSA-positive and 60 cases of dnDSA-negative. The incidence of AR was 2.09% (5/239) in HLA antibody-negative patients, 18.33% (11/60) in HLA antibody positive with DSA-negative patients, and 83.33% (5/6) in HLA antibody-positive patients with DSA-positive. There was a big difference between DSA-negative and DSA-positive patients (p < 0.01). The recovery time of AR patients with DSA-positive were longer than DSA-negative patients, and the recovery graft function of AR patient with DSA-positive were not as good as those with DSA-negative. Conclusions: The appearance of dnDSA in the early stage of kidney transplantation is a warning sign of AR occurrence. Dynamic monitoring of HLA antibody and DSA could predict the state of graft function, and play an important role in the prevention of AR, timely and effectively.

Survival in Sensitized Lung Transplant Recipients With Perioperative Desensitization

Donor-specific HLA antibodies (DSA) have an adverse effect on short-term and long-term lung transplant outcomes. We implemented a perioperative strategy to treat DSA-positive recipients, leading to equivalent rejection and graft survival outcomes. Pretransplant DSA were identified to HLA-A, B, C, DR and DQ antigens. DSA-positive patients were transplanted if panel reactive antibody (PRA) ≥30% or medically urgent and desensitized with perioperative plasma exchange, intravenous immune globulin, antithymocyte globulin (ATG), and mycophenolic acid (MPA). PRA-positive/DSA-negative recipients received MPA. Unsensitized patients received routine cyclosporine, azathioprine and prednisone without ATG. From 2008-2011, 340 lung-only first transplants were performed: 53 DSA-positive, 93 PRA-positive/DSA-negative and 194 unsensitized. Thirty-day survival was 96 %/99%/96% in the three groups, respectively. One-year graft survival was 89%/88%/86% (p = 0.47). DSA-positive and PRA-positive/DSA-negative patients were less likely to experience any ≥ grade 2 acute rejection (9% and 9% vs. 18% unsensitized p = 0.04). Maximum predicted forced expiratory volume (1 s) (81%/74%/76%, p = NS) and predicted forced vital capacity (81%/77%/78%, respectively, p = NS) were equivalent between groups. With the application of this perioperative treatment protocol, lung transplantation can be safely performed in DSA/PRA-positive patients, with similar outcomes to unsensitized recipients.

Clinical Outcome of DSA Positive Alone in Kidney Transplantation.

Cell based assay (CDC or FCXM) methods, can identify antibodies that can mediated acute humoral rejection. Furthermore recent new solid phase assay, by single bead PRA (Luminex®) is more sensitive method for detection of anti-donor antibody. However the need and benefit of desensitization for DSA positive but FCXM negative patients are controversial. From Aug 2012 to Dec 2013 we had performed 481 kidney transplantations. Among them 29 patients were DSA positive alone patients (FCXM negative). Eight patients were excluded because they were ABO incompatible kidney transplant recipients who need preoperative desensitization. In these 21 patients simulect® induction followed by triple immunosuppressant was used without preoperative desensitization. Eleven (52.3%) patients were male, 7(33%) from deceased donor, and five retransplant patients. Mean FCXM MFI value was 1.1(reference value; positive ≥2.0). Mean PRA class I and II was 53% and 55% respectively. DSA MFI value was 2039 (1008-5744) in Class I and 3356 (1073-9933) in class II HLA antigen. One year patient and graft survival were 95.2% each (1 case of mortality from infection). During mean 344 ±142 days of follow up, 5 rejection episodes were developed (23.8% 1 year rejection rate). Among whom, 2 case of antibody mediated rejection, 2 case of cellular rejection and one case of mixed rejection were developed. Interestingly rejections were developed during relatively early postoperative period (Median 17 days) and relatively severe rejection (IB, IIA and IIB), but all reversed by plasmapheresis, rituximab and IVIG. In the analysis of the risk factor for rejection, we could not detect any factors affecting rejection, such as the intensity of DSA or value of cPRA. Although all the rejections were was reversible by rescue therapy and majority of patients does not developed acute rejection, DSA positive alone patients had relative higher rejection rate. Careful follow up and monitoring may be mandatory in this category patients, and desensitization might be needed in some patients according to further analysis.

Pre-transplant donor HLA-specific antibodies: Characteristics causing detrimental effects on survival after lung transplantation

The impact of Luminex-detected HLA antibodies on outcomes after lung transplantation is unclear. Herein we have undertaken a retrospective study of pre-transplant sera from 425 lung transplants performed between 1991 and 2003. Pre-transplant sera, originally screened by complement-dependent cytotoxicity (CDC) assays, were retrospectively tested for the presence of HLA-specific antibodies using HLA-coated Luminex beads and C4d deposition on Luminex beads. The results were correlated with graft survival at 1 year. Twenty-seven patients were retrospectively identified as having been transplanted against donor-specific HLA antibodies (DSA) and 36 patients against non-donor-specific HLA antibodies (NDSA). DSA-positive patients had 1-year survival of 51.9% compared with 77.8% for NDSA and 71.8% for antibody-negative patients (p = 0.029). One-year survival of patients with complement-fixing DSA was 12.5% compared with 62.5% for non-complement-fixing DSA, 75.8% for non-complement-fixing NDSA and 71.8% for antibody-negative patients (p < 0.0001). DSA-positive patients with mean fluorescence intensity (MFI) >5,000 had 1-year survival of 33.3% compared with 71.4% for MFI 2,000 to 5000 and 62.5% for MFI <2,000 (p = 0.0046). Multivariable analysis revealed DSA to be an independent predictor of poor patient survival within 1 year (p = 0.0010, hazard ratio [HR] = 3.569) as well as complement-fixing DSA (p < 0.0001, HR = 11.083) and DSA with MFI >5,000 (p = 0.0001, HR = 5.512). Pre-formed DSA, particularly complement-fixing DSA, and high MFI are associated with poor survival within the first year after lung transplantation. Risk stratification according to complement fixation or MFI levels may allow for increased transplantation in sensitized patients.

Pediatric kidney recipients may benefit from monitoring for donor‐specific antibodies

There are limited data regarding the presence of DSAs and their effect on graft function in pediatric renal transplantation. The role for serial DSA monitoring in routine clinical practice is unclear. All patients attending a regional transplant clinic were tested for DSAs, measured using Luminex single/mixed antigen beads. Any patient having a positive result subsequently underwent historic testing on samples previously obtained. DSA-positive patients underwent prospective monitoring of DSAs, and correlation with clinical events was studied. Nine of a total of 50 patients (18%) were DSA-positive, of whom six had graft dysfunction. The DSA-positive cohort had significantly increased episodes of AR (p = 0.01). There were two graft losses in the DSA-positive group and none in the DSA-negative group. Eight of the DSA-positive group had potentially reduced exposure to IS because of either adherence issues or clinical indications. DSAs were associated with increased risk of rejection. There appears to be a role for serial monitoring of DSAs in patients where there has been a reduced exposure to IS so that early intervention with optimized IS can be considered.

Chronic vascular rejection - a common finding in the lung allograft is associated with features of antibody mediated rejection

Aims To determine the frequency of chronic vascular rejection (CVR) in the lung allograft and its association with donor-specific antibodies (DSA) in the serum, and features of acute antibody-mediated rejection (AMR) in transbronchial biopsies (TBBx). Methods We retrospectively analysed the lung allografts of transplant recipients for CVR and collated their prior TBBx and Luminex test (for DSA) results. We longitudinally studied a cohort of lung transplant recipients and recorded Luminex tests, TBBx and survival data. Fisher’s exact test and Kaplan-Meier survival analysis were performed. Results CVR was identified in 58.62% of lung allografts (n = 31), and was associated with DSA (p = 0.0043). DSA-positive patients with a TBBx featuring interstitial neutrophils (IN) within 50 days post-transplant (excluding concurrent infection or cellular rejection) were likely to develop CVR (p = 0.0174). In the longitudinal study, 45.64% of patients were DSA positive (n = 195); these patients were more likely to record a TBBx featuring IN (as per above specifications; p = 0.0376), and had worse long-term graft function (p = 0.0015). Conclusion: CVR is common in lung allografts. The presence of DSA and TBBx features of acute AMR should heighten suspicion for the potential development of CVR and graft failure.

The Presence of Anti-HLA Donor-Specific Antibodies in Lung Allograft Recipients Does Not Correlate With C4d Immunofluorescence in Transbronchial Biopsy Specimens

C4d immunofluorescence (IF) is a surrogate for development of donor-specific antibodies (DSAs) against human leukocyte antigen (HLA) class I and II antigens in kidney and heart biopsy specimens for monitoring of antibody-mediated (humoral) allograft rejection (AMR). Use of C4d IF in monitoring of lung allografts has shown conflicting results. To determine if C4d IF can be used as a reliable marker for AMR and if it correlates with the presence of DSAs and histologic findings on biopsy. All transbronchial biopsies in lung allograft recipients, performed at our institution in a 3-year period, were reviewed. A cohort of 92 patients with 110 corresponding biopsies met the inclusion criteria of (1) having a resulted DSA within 2 weeks of biopsy and (2) having C4d immunofluorescence studies performed and confirmed. Twenty-nine patients (31.5%) were positive for DSAs and 63 patients (68.5%) did not develop DSAs. Positive C4d capillary IF was seen in 18 of 110 total biopsy specimens (16.4%). Eight of these biopsy samples were from patients positive for DSAs and 10 were from patients negative for DSAs. The correlation coefficient between the presence of DSAs and C4d IF was 0.1628 (P = .09). A significant proportion of DSA-positive patients had negative C4d IF results and frequently have no histologic changes on biopsy specimens. DSA-negative patients can be positive for C4d and may show the same histologic changes as reported for DSA-positive patients. Diagnosis of AMR in lung may require a collaborative approach combining clinical data, DSA status, and histology.

The Impact of De Novo Donor-specific Anti-Human Leukocyte Antigen Antibodies on 5-Year Renal Transplant Outcome

Numerous studies have shown that circulating donor-specific antibodies targeting human leukocyte antigen (HLA) are associated with accelerated renal transplant failure, but many patients with these antibodies have good graft function. The aim of our study was to investigate the long-term graft function and survival in patients with de novo post-transplant donor-specific anti-HLA antibodies (DSA). Our prospective study included 78 consecutive recipients with a negative crossmatch before transplantation. Recipient serum samples were assayed for DSA in week 2 and 1, 3, 6, 9, 12 months after transplantation using a complement-dependent lymphocytotoxic technique with donor lymphocytes. Additionally, patients with DSA and stable renal function in the first year were tested with a more sensitive flow-panel-reactive antibody. DSA were present in 34 (44%) of our patients during the first 12 months after transplantation. Biopsy-proved acute rejection occurred in 11 DSA-positive and 10 DSA-negative patients. Seven DSA-positive patients had antibody-mediated rejection and no DSA-negative ones developed humoral rejection. The serum creatinine level in DSA-positive patients was significantly higher (2.48 vs 1.43 mg/dL) in year 5. The 13 (38%) DSA-positive patients with good graft function in month 12 were stable during a 5-year follow-up: their serum creatinine was 1.46 ± 0.4 in year 1 and 1.56 ± 0.4 mg/dL in year 5 and nobody lost their allograft. One- and 5- year graft survivals were appropriately 85% and 59% in DSA-positive patients compared to 93% and 93% in DSA-negative patients. To sum up, post-transplant DSA had a significant influence on kidney function and graft survival but in 38% of patients the presence of DSA did not decrease a 5-year renal function. A good renal allograft function in the presence of DSA in the first year after transplantation and cessation of their production in the subsequent years may be a good prognostic marker for a long-term allograft function and survival.

Kidney Transplantation in Immunologically High-Risk Patients

An increased number of sensitized patients await kidney transplantation (KTx). Sensitization has a major impact on patient mortality and morbidity due to prolonged waiting time and may preclude live donor transplantation. However, recent reports have shown that KTx can be performed successfully using novel immunosuppressive protocols. This study presents our experience with patients displaying donor-specific antibody (DSA) (+). We enrolled 5 lymphocyte cross-match (LCM) negative (complement-dependent cytotoxicity) and panel-reactive antibody (PRA) plus DSA-positive patients mean fluorescein intensity [MFI] > 1000) who underwent living kidney donor procedures. All subjects were females and their mean age was 36.7 years. In our protocol, we started mycophenolate mofetil (2 g/d), tacrolimus (0.01 mg/kg) and prednisolone (0.5 mg/kg) on day −6. We performed 2 sessions of total plasma exchange (TPE) with albumin replacement and administered 2 doses of IVIG (5 g/d). On day −1, we added rituximab (200 mg). On the operation day and on day +4, the patients received doses of basiliximab. Serum samples were taken on days −6, 0, and 30 as well as at 1 year after transplantation. All patients displayed immediate graft function. Mean basal DSA titer was 5624 MFI. After desensitization, the MFI titers decreased at the time of transplantation to 2753 MFI, and were 2564 MFI at the 1st month and 802 MFI at 1st year. Three patients experienced acute rejection episodes (60%). After treatment for rejection, the average follow-up was 17 months and last creatinine levels were 0.6–0.8 mg/dL (minimum-maximum). In conclusion, KTx can be succesfully performed in sensitized patients displaying DSA. However, there seems to be a greater acute rejection risk. There is no consensus regarding adequate doses of IVIG or plasmapheresis treatments; furthermore, more studies are needed to clarify the safe MFI titer of the DSA.

Humoral theory of transplantation: some hot topics

Antibody is a major cause of allograft injury. However, it has not been routinely tested post-transplant. A literature search was performed using PubMed on the topics of 'antibody monitoring', 'autoantibody and allograft dysfunction' and 'prevention and treatment of antibody-mediated rejection (AMR)'. Donor-specific antibody (DSA) monitoring not only helps to identify patients at risk of AMR, but also serves as a biomarker to personalize patient's maintenance immunosuppression. Development of autoantibody is a secondary response following primary tissue injury. Some autoantibodies are directly involved in allograft injury, while others only serve as biomarkers of tissue injury. It remains controversial whether DSA-positive patients without symptoms need to be treated. In addition, given the variation in study designs and patient's characteristics, there is discrepancy regarding which treatment regimens provide optimal clinical outcome in preventing/treating AMR. Efficacy of B-cell and/or antibody-targeted therapies in treating or preventing AMR would be better measured by the incorporation of antibody monitoring into current functional and pathological assays. Research in B-cell targeted therapies to prevent and treat AMR is rapidly growing, which includes monoclonal antibodies against B-cell markers CD20, CD40, CD19, BlyS, etc. It requires extensive clinical research to determine the best approach to inhibit or delete antibody and how to balance the drug efficacy with safety.

The Significance of Low Level DSA Detected by Solid Phase Assay in Association with Acute and Chronic Antibody Mediated Rejection

Background: Introduction of solid-phase assays (SPA), including ELISA, and multiple beads technology, of which the Luminex bead assays are one type, enable more sensitive detection of anti-donor specific HLA antibody (DSA). However, evidence on the relevance between clinical outcome and low level DSA which is detected by these sensitive assays is still conflicting. In our department, DSA detected by only SPA but not by complement-dependent cytotoxic (CDC) crossmatch assay is considered as low level (Luminex MFI of those low level DSAs showed more than 800 and less than 2500). Here in, we retrospectively studied ABO-compatible living kidney transplantation recipients with those low level DSA. Patients and Results: Between 2001 and 2009, 88 recipients with preoperative low level DSA underwent ABO-compatible kidney transplantation. Twenty-four patients were performed transplantation without any desensitization(Control group). The incidence of acute and chronic AMR of this group were high despite their weak sensitized status (acute AMR; 33.3%, chronic AMR; 41.7%). On the other hand, sixty-four recipients were performed kidney transplantation with the administration of a single dose of rituximab (RIT) and three or four sessions of double-filtration plasmapheresis (DFPP) in addition to the immunosuppressive regimens commonly used in the control group (RIT/DFPP group). In the latter group, the incident rate of acute and chronic AMR significantly reduced (acute AMR; 4.7%, P< 0.001, chronic AMR; 4.7%, P< 0.001). The five year graft survival rate also improved in the RIT/DFPP group (87% to 98%, P=0.076).[Fig 1][Fig 2]Conclusion: RIT/DFPP induction for DSA-positive recipients determined by Luminex prevented acute and chronic rejection without noted adverse events and achieved good graft function and graft survival compared to the induction group who did not have RIT/DFPP. Long-term depletion of pre-transplant DSA was also observed in this study. Our induction seems to be a good option for these low DSA positive patients because of its efficacy and safeness.