Acute Humoral Rejection in Hepatitis C-Infected Renal Transplant Recipients Receiving Antiviral Therapy

The use of interferon-alpha (IFN) in hepatitis C (HCV)-infected renal recipients has been associated with acute rejection and graft loss. We reviewed our recent experience in HCV (+) renal recipients treated with antiviral therapy for biopsy proven chronic hepatitis C. Twelve HCV (+) recipients who recently received antiviral therapy were analyzed. Post-treatment sera were tested for donor-specific human leukocyte antigen (HLA) antibodies (DSA). Within 6 months of initiating antiviral therapy, two of 12 patients (17%) developed acute rejection, which was characterized as acute humoral rejection (de novo DSA in serum and C4d deposits in peritubular capillaries). Both progressed to graft failure. Nine of the remaining 10 patients tested did not have DSA. The use of IFN was associated with severe acute humoral rejection (C4d +, DSA +). The recognition of IFN-associated acute humoral rejection in this series may explain the high rate of graft loss reported previously in renal recipients receiving IFN.     

Characterization of rejection episodes in patients following positive crossmatch and ABO-incompatible live donor renal transplantation

For kidney transplant recipients with donor-specific antibody (DSA) to HLA- (+XM) or ABO-antigens (ABOI), there is a need to improve detection and treatment of antibody-mediated rejection (AMR). The methods included a retrospective review of consecutive patients that received plasmapheresis and immune globulin (PPIVIg) to abrogate +XM or ABOI. Twelve patients were transplanted after PPIVIg (+XM = 9, ABOI = 2, +XM/ABOI = 1). No hyperacute rejections occurred. Rejection occurred in seven patients [four AMR, three acute cellular rejection (ACR)]. In four +XM patients, DSA was detected during graft dysfunction despite lack of histologic and C4d features of AMR. In one patient, DSA preceded the histologic and immunofluorescent features of AMR. In another patient with borderline changes and DSA, graft function improved after PPIVIg, despite lack of histologic or immunofluorescent evidence of AMR. One patient with Banff IIA ACR and DSA treated with antithymocyte antibody but not PPIVIg had recurrent rejections and poor graft function. In +XM and ABOI recipients with graft dysfunction: (i) DSA may represent AMR in the absence of C4d or histologic features of AMR; (ii) DSA can precede C4d or light microscopic features of AMR; (iii) A poor outcome may result if DSA or continued allograft dysfunction is present and not treated despite a negative biopsy.     

Preformed and De Novo Donor Specific Antibodies in Visceral Transplantation: Long‐Term Outcome With Special Reference to the Liver

Despite improvement in early outcome, rejection particularly chronic allograft enteropathy continues to be a major barrier to long‐term visceral engraftment. The potential role of donor specific antibodies (DSA) was examined in 194 primary adult recipients. All underwent complement‐dependent lymphocytotoxic crossmatch (CDC‐XM) with pre‐ and posttransplant solid phase HLA–DSA assay in 156 (80%). Grafts were ABO‐identical with random HLA‐match. Liver was included in 71 (37%) allografts. Immunosuppression was tacrolimus‐based with antilymphocyte recipient pretreatment in 150 (77%). CDC‐XM was positive in 55 (28%). HLA–DSA was detectable before transplant in 49 (31%) recipients with 19 continuing to have circulating antibodies. Another 19 (18%) developed de novo DSA. Ninety percent of patients with preformed DSA harbored HLA Class‐I whereas 74% of recipients with de novo antibodies had Class‐II. Gender, age, ABO blood‐type, cold ischemia, splenectomy and allograft type were significant DSA predictors. Preformed DSA significantly (p < 0.05) increased risk of acute rejection. Persistent and de novo HLA–DSA significantly (p < 0.001) increased risk of chronic rejection and associated graft loss. Inclusion of the liver was a significant predictor of better outcome (p = 0.004, HR = 0.347) with significant clearance of preformed antibodies (p = 0.04, OR = 56) and lower induction of de novo DSA (p = 0.07, OR = 24). Innovative multifaceted anti‐DSA strategies are required to further improve long‐term survival particularly of liver‐free allografts.     

The Significance of Donor‐Specific HLA Antibodies in Rejection and Ductopenia Development in ABO Compatible Liver Transplantation

The role of humoral alloreactivity in ABO‐compatible liver transplantation remains unclear. To understand the significance of donor‐specific HLA alloantibodies (DSA) in liver rejection, we applied the currently used strategy for detection of antibody‐mediated rejection of other solid allografts. For this purpose we reviewed the data on 43 recipients of ABO identical/compatible donor livers who had indication liver biopsy stained for complement element C4d and contemporaneous circulating DSA determination. Seventeen (40%) patients had significant circulating DSA in association with diffuse portal C4d deposition (DSA+/diffuse C4d+). These DSA+/diffuse C4d+ subjects had higher frequency of acute cellular rejection (ACR) 15/17 versus 13/26 (88% vs. 50%), p = 0.02, and steroid resistant rejection 7/17 versus 5/26 (41% vs. 19%), p = 0.03. Based on detection of the combination DSA+/diffuse C4d+, 53.6% of cases of ACR had evidence of concurrent humoral alloreactivity. Six of the 10 patients with ductopenic rejection had circulating DSA and diffuse portal C4d, three of whom (2 early and 1 late posttransplantation) developed unrelenting cholestasis, necessitating specific antibody‐depleting therapy to salvage the allografts. Thus, in ABO‐compatible liver transplantation humoral alloreactivity mediated by antibodies against donor HLA molecules appears to be frequently intertwined with cellular mechanisms of rejection, and to play a role in ductopenia development.     

Significance of HLA-matching and anti-HLA antibodies in heart transplant patients receiving induction therapy?

ObjectivesThough Human Leukocyte Antigen (HLA) matching benefits are demonstrated in renal transplantation, evidence in heart transplantation is lacking, and its clinical feasibility is uncertain. Post-transplantation anti-HLA antibodies are being increasingly studied in organ transplantation, with diverging conclusions between transplantated organs.MethodsWe analyzed retrospectively the influence of HLA matching and anti-HLA antibodies on overall survival, acute rejection and chronic allograft vasculopathy in 309 patients receiving induction therapy and triple-drug immunosuppression.ResultsThe average number of HLA-A/B/DR mismatches between donor and recipient was 4.9 ± 1. The majority of mismatches was for Class I HLA-A/B with an average of 3.3, then for Class I HLA-DR with an average of 1.6. Overall, the HLA-A/-B/-DR mismatches had no influence on the cardiac allograft survival (p = 0.28). However, HLA-DR mismatches were negatively correlated to severe cellular and/or humoral allograft rejection (p = 0.04). Our analysis found anti-HLA antibodies in 27% of recipients, de novo anti-HLA antibodies in 16% of recipients, and donor-specific anti-HLA (DSA) antibodies in 8% of recipients. Furthermore, de novo DSA had no influence on the 5-year survival (78% with DSA vs. 92% without DSA; p = 0.49), which may be masked by the limited number of recipients in analysis By univariable analysis, anti-HLA antibodies (preexisting or de novo) unrelated or related to the donor had no influence on severe cellular and/or humoral rejection or on chronic allograft vasculopathy.ConclusionsHLA-DR mismatch was negatively correlated to severe cellular and/or humoral allograft rejection but had no influence on cardiac allograft survival. In this study, anti-HLA antibodies (preexisting or de novo) unrelated or related to the donor had no influence on cellular and/or humoral rejection or on chronic allograft vasculopathy. The results of this study add to the controversy on the impact of allo-antibodies in heart transplant recipients receiving induction therapy and contemporary immunosuppression.     

Class II Alloantibody and Mortality in Simultaneous Liver‐Kidney Transplantation

Hyperacute kidney rejection is unusual in crossmatch positive recipients of simultaneous liver–kidney transplants (SLKT). However, recent data suggest that these patients remain at risk for antibody‐mediated kidney rejection. To further investigate the risk associated with donor‐specific alloantibodies (DSA) in SLKT, we studied 86 consecutive SLKT patients with an available pre‐SLKT serum sample. Serum samples were analyzed in a blinded fashion for HLA DSA using single antigen beads (median florescence intensity ≥ 2,000 = positive). Post‐SLKT samples were analyzed when available (76%). Thirty patients had preformed DSA, and nine developed de novo DSA. Preformed class I DSA did not change the risk of rejection, patient or allograft survival. In contrast, preformed class II DSA was associated with a markedly increased risk of renal antibody mediated rejection (AMR) (p = 0.006), liver allograft rejection (p = 0.002), patient death (p = 0.02), liver allograft loss (p = 0.02) and renal allograft loss (p = 0.045). Multivariable modeling showed class II DSA (preformed or de novo) to be an independent predictor of patient death (HR = 2.2; p = 0.043) and liver allograft loss (HR = 2.2; p = 0.044). These data warrant reconsideration of the approach to DSA in SLKT.     

Renal allograft biopsies in the era of C4d staining: the need for change in the Banff classification system.

C4d immunostaining in the peritubular capillaries (PTC) is a marker of antibody-mediated rejection (AMR). We evaluated the histopathologic diagnoses of 388 renal transplant biopsies since the implementation of routine C4d immunostaining at our center. Of these, 155 (40%) biopsies had evidence of acute cellular rejection (ACR), out of which 119 (77%) had pure ACR, 31 (20%) had ACR with concomitant features of AMR, and five (3%) had ACR with focal C4d staining. Sixty-four (16%) biopsies exhibited features of AMR [33 (52%) pure AMR, and 31(48%) concomitant AMR and ACR]. One hundred and fifty-five (40%) biopsies had features of interstitial fibrosis and tubular atrophy (IFTA). Of these, 20 (13%) had concomitant AMR [13 (8.5%) had pure AMR and seven (4.5%) had concomitant ACR and AMR]. Creatinine at the time of biopsy was higher in patients with mixed ACR and AMR and the clinical behavior of mixed lesions is more aggressive over time. Despite having a lower serum creatinine at the time of biopsy, patients with IFTA experienced gradual decline in graft function over time. The pathologic findings in renal allograft biopsies are often mixed and mixed lesions appear to have more aggressive clinical behavior. These findings suggest the need for change in the Banff classification system to better capture the complexity of renal allograft pathologies.     

Upfront use of eculizumab to treat early acute antibody-mediated rejection after kidney allotransplantation and relevance for xenotransplantation

Acute antibody-mediated rejection (AMR) early after transplant remains a challenge, both in allotransplantation and in xenotransplantation. We report the case of an early and severe acute AMR episode in a kidney transplant recipient that was successfully treated with upfront eculizumab. A 58-year-old woman had been on dialysis since 2014. She underwent a first kidney transplant in 2018 with primary non-function and received several blood transfusions. Postoperatively, she developed anti-HLA antibodies. One year later, she received a second allograft from a deceased donor. At day 0, there was only one preformed low-level donor-specific antibody (DSA) anti-DQ7. After initial excellent allograft function, serum creatinine increased on days 7-9, and this was associated with oligo-anuria. On day 7, there was an increase in her DSA anti-DQ7 and 4 de novo DSA had developed at high MFI values. Allograft biopsy showed severe active AMR with diffuse C4d deposits in peritubular capillaries. The early acute AMR episode was treated with upfront eculizumab administration (2 doses) with efficient CH50 blockade (< 10% CH50). Rituximab was also administered on day 12, and intravenous immunoglobulin (IVIG) was given over the following days. There was an excellent clinical response to eculizumab administration. Eculizumab administration rapidly reversed the acute AMR episode without the need for plasmapheresis. Rituximab and IVIG were also used as B-cell immunomodulators to decrease DSA. Blocking efficiently the terminal complement pathway may become a useful strategy to treat acute AMR in sensitized recipients of allografts, and possibly in recipients of discordant xenografts.     

Conversion to belatacept within 1-year of renal transplantation in a diverse cohort including patients with donor-specific antibodies

Early conversion from a calcineurin inhibitor to belatacept has the potential to improve long-term renal allograft function; however, there remains limited experience with this strategy among African Americans and patients with preformed donor-specific antibodies (DSA). To examine these subgroups, we performed a single-center review of kidney transplant recipients converted to belatacept within 1-year of transplant between 01/2011 and 10/2017. All patients received lymphocyte-depleting induction with maintenance tacrolimus and mycophenolate +/− corticosteroids. Patients were switched to belatacept for clinical indication and followed from date of conversion until allograft failure or study conclusion. The primary endpoint at 1-year was a composite of allograft loss, biopsy proven rejection, de novo DSA formation, proteinuria, and declining renal function. Thirty-two patients were included in the review. The majority were African American, and 28.1% had DSA at transplant. Patient and allograft survival at 1-year was 96.9% and 93.8%, respectively, and estimated glomerular filtration rate improved from 41.9 to 58.4 mL/min. No African Americans or patients with pretreatment DSA developed rejection or allograft failure within 1-year. The only clinical variable correlated with suboptimal allograft function was baseline weight ≥80 kg (OR = 6.2; 95% CI, 1.2-32.3). Early conversion to belatacept appears safe for select patients with DSA and African Americans receiving lymphocyte-depleting induction.     

Therapy with plasmapheresis and intravenous immunoglobulin for acute humoral rejection in kidney transplantation

BACKGROUND: Acute humoral rejection (AHR) is characterized by acute graft dysfunction associated with de novo production of donor-specific alloantibodies (DSA) and C4d deposition in peritubular capillaries of the renal allograft. It has been reported the combination of plasmapheresis (PP) and intravenous gamma globulin (IVIG) as effective rescue therapy for established AHR. METHODS: Between 1999 and 2004, seven kidney allografts recipients suffered from AHR diagnosed by severe rejection and C4d staining in peritubular capillaries. All patients had a negative cross-match before renal transplantation. RESULTS: All patients were treated with daily sessions of PP and in four cases IVIG was added after the last PP session. Tacrolimus and mycophenolate mofetil were employed as maintenance immunosuppressive regimen. In one case, rituximab was added to PP and IVIG owing to refractory humoral rejection. At 1 year, patient survival was 100%, allograft survival was 70%, and the mean serum creatinine was 201 micromol/L. CONCLUSIONS: AHR is a severe form of rejection associated with a poor prognosis, but its early diagnosis and treatment with PP and IVIG allows reversal of AHR reaching a 70% graft survival at 1 year.     

De Novo Donor-Specific Antibody at the Time of Kidney Transplant Biopsy Associates with Microvascular Pathology and Late Graft Failure

We studied whether de novo donor-specific antibodies (DSA) in sera from patients undergoing kidney transplant biopsies associate with specific histologic lesions in the biopsy and prognosis. DSA were assessed in 145 patients at the time of biopsy between 7 days to 31 years posttransplant. DSA was detected in 54 patients (37%), of which 32 represented de novo DSA. De novo DSA was more frequent in patients having late biopsies (34%) versus early biopsies (4%), and was usually either against class II alone or class I and II but rarely against class I alone. Microcirculation inflammation (glomerulitis, capillaritis) and damage (glomuerulopathy, capillary basement membrane multilayering), and C4d staining were associated with de novo DSA. However, the degree of scarring, arterial fibrosis and tubulo-interstitial inflammation did not correlate with the presence of de novo DSA. De novo DSA correlated with reduced graft survival after the biopsy. Thus, de novo DSA at the time of a late biopsy for clinical indication is primarily against class II, and associates with microcirculation changes in the biopsy and subsequent graft failure. We propose careful assessment of de novo DSA, particularly against class II, be performed in all late kidney transplant biopsies.     

肾移植一年后急性排斥反应时移植肾组织中C4d表达阳性的临床研究

目的 观察肾移植1年后发生急性排斥反应时移植肾组织中补体片段C4d的表达情况,分析其对移植肾功能及预后的影响.方法 选择肾移植时间超过1年,临床诊断为急性排斥反应并经病理穿刺活检证实的肾移植受者36例为研究对象.以第1例受者移植肾组织穿刺时间为观察起点(2006年3月),以此项研究结束时间为观察终点(2010年4月).应用C4d多克隆抗体对移植肾穿刺组织行免疫组织化学染色,检测C4d在移植肾组织中的表达情况;根据检测结果,分为C4d阳性组和阴性组,分析和比较两组在观察时间段内移植肾功能的变化及存活时间.结果 在36例受者的移植肾穿刺标本中,C4d阳性16例(44.4%),C4d阴性20例(55.6%);C4d阳性组和阴性组移植肾组织中嗜酸性粒细胞浸润数量分别为(9.4±4.5)个和(2.6±1.8)个,两组比较,差异有统计学意义(P＜0.05).在观察时间段内,所有受者血清肌酐均有不同程度上升,但C4d阳性组上升幅度与C4d阴性组比较,差异无统计学意义(P＞0.05);C4d阳性组和C4d阴性组受者移植肾功能丧失率分别为31.3%(5/16)和30.0%(6/20),两组比较,差异无统计学意义(P＞0.05).C4d阳性组和C4d阴性组受者移植肾穿刺后的巾位存活时间分别为(19.3±5.3)个月和(22.5±7.4)个月,两组比较,差异无统计学意义(P＞0.05).结论 肾移植1年后发生急性排斥反应时,移植肾组织中C4d表达阳性对其功能及存活时间无明显影响.     

Significance of C1q-fixing Donor-Specific Antibodies After Kidney Transplantation

Objectives

De novo donor-specific HLA antibodies (DSA) are associated with allograft rejection and allograft loss. However, not all DSA are equally detrimental to allograft function. The ability to activate complement may be an important factor differentiating clinically relevant DSA from nonrelevant DSA. The C1q assay detects a subset of HLA antibodies that can fix complement. This study aimed to investigate the correlation between C1q-fixing de novo DSA (dnDSA) and clinical outcomes posttransplant.

Methods

This retrospective study included 193 sera from kidney transplant recipients who underwent posttransplant DSA testing and/or kidney biopsy for clinical causes. Thirty-five of the 193 (18.1%) had immunoglobulin G DSA. Seventeen of the 35 patients were excluded owing to the presence of pretransplant HLA antibodies. We then analyzed C1q DSA at the time of biopsy in 18 recipients who developed dnDSA. The clinical outcomes of patients with C1q-positive DSA and C1q-negative DSA were compared.

Results

C1q-positive DSA were detected in 10 of 18 patients (55.6%). The incidences of transplant glomerulopathy were significantly higher among patients with C1q-positive DSA than patients with C1q-negative DSA (80% vs 0%; P = .001). Although patients with C1q-positive DSA experienced more chronic antibody-mediated rejection and graft loss (80% vs 37.5% [P = .145]; 60% vs 25% [P = .188]), the differences were not significant. The receiver operating characteristic curve analysis showed that the C1q assay was an excellent predictor of transplant glomerulopathy with area under the curve of 0.9 (95% CI, 0.769–1.000).

Conclusion

The presence of C1q-positive dnDSA was associated with an increased risk of transplant glomerulopathy. The C1q assay is potentially a powerful method for identifying patients at risk for transplant glomerulopathy.     

Re‐examination of the Lymphocytotoxic Crossmatch in Liver Transplantation: Can C4d Stains Help in Monitoring?

C4d-assisted recognition of antibody-mediated rejection (AMR) in formalin-fixed paraffin-embedded tissues (FFPE) from donor-specific antibody-positive (DSA+) renal allograft recipients prompted study of DSA+ liver allograft recipients as measured by lymphocytotoxic crossmatch (XM) and/or Luminex. XM results did not influence patient or allograft survival, or cellular rejection rates, but XM+ recipients received significantly more prophylactic steroids. Endothelial C4d staining strongly correlates with XM+ (<3 weeks posttransplantation) and DSA+ status and cellular rejection, but not with worse Banff grading or treatment response. Diffuse C4d staining, XM+, DSA+ and ABO- incompatibility status, histopathology and clinical-serologic profile helped establish an isolated AMR diagnosis in 5 of 100 (5%) XM+ and one ABO-incompatible, recipients. C4d staining later after transplantation was associated with rejection and nonrejection-related causes of allograft dysfunction in DSA- and DSA+ recipients, some of whom had good outcomes without additional therapy. Liver allograft FFPE C4d staining: (a) can help classify liver allograft dysfunction; (b) substantiates antibody contribution to rejection; (c) probably represents nonalloantibody insults and/or complete absorption in DSA- recipients and (d) alone, is an imperfect AMR marker needing correlation with routine histopathology, clinical and serologic profiles. Further study in late biopsies and other tissue markers of liver AMR with simultaneous DSA measurements are needed.     

Anti‐huCD20 Antibody Therapy for Antibody‐Mediated Rejection of Renal Allografts in a Mouse Model

We have reported that B6.CCR5^?/? mice reject renal allografts with high serum donor‐specific antibody (DSA) titers and marked C4d deposition in grafts, features consistent with antibody‐mediated rejection (AMR). B6.huCD20/CCR5^?/? mice, where human CD20 expression is restricted to B cells, rejected A/J renal allografts by day 26 posttransplant with DSA first detected in serum on day 5 posttransplant and increased thereafter. Recipient treatment with anti‐huCD20 mAb prior to the transplant and weekly up to 7 weeks posttransplant promoted long‐term allograft survival (>100 days) with low DSA titers. To investigate the effect of B cell depletion at the time serum DSA was first detected, recipients were treated with anti‐huCD20 mAb on days 5, 8, and 12 posttransplant. This regimen significantly reduced DSA titers and graft inflammation on day 15 posttransplant and prolonged allograft survival >60 days. However, DSA returned to the titers observed in control treated recipients by day 30 posttransplant and histological analyses on day 60 posttransplant indicated severe interstitial fibrosis. These results indicate that anti‐huCD20 mAb had the greatest effect as a prophylactic treatment and that the distinct kinetics of DSA responses accounts for acute renal allograft failure versus the development of fibrosis.

     

Impact of pretransplant donor‐specific antibodies on kidney allograft recipients with negative flow cytometry cross‐matches

The Luminex test can detect low levels of donor‐specific antibody (DSA) that cannot be detected by flow‐cytometric cross‐matching (FCXM) in kidney transplantation (KT). This study evaluated the impact of DSA on clinical outcomes in KT recipients negative on FCXM. Of 575 consecutive patients who underwent living donor KT between January 2013 and July 2016, 494 (85.9%) were DSA‐negative and 81 (14.1%) were DSA‐positive. Although rates of acute cellular rejection (ACR) at 1 year were similar in the 2 groups (P = .54), the incidence of antibody‐mediated rejection (ABMR) was significantly higher in the DSA‐positive group (P < .01). There was no statistically significant association between rejection‐free graft survival (RFGS) rates and pretransplant class I DSA. However, evaluation of pretransplant class II DSA showed that RFGS rates were significantly lower in patients with mean fluorescence intensity (MFI) >3000 than in patients with DSA‐negative (P < .01). On multivariate analyses, class II DSA MFI ≥5000 was a significant risk factor for acute rejection (hazard ratio, 7.48; P < .01). These findings suggested that pretransplant DSA alone did not affect graft survival in KT recipients without desensitization. However, class II DSA MFI >5000 was an independent predictor of acute rejection in DSA‐positive patients.     

A case of allograft dysfunction with antibody-mediated rejection developing 13 yr after kidney transplantation

Abstract:  Antibody-mediated rejection is an important cause of chronic allograft dysfunction. We report a case of chronic antibody-mediated rejection 13 yr after transplantation. This patient is a 19-yr-old man who had renal insufficiency since infancy because of bilateral polycystic kidneys. Peritoneal dialysis was started when he was four yr old and he received a renal allograft from his mother at the age of six yr. Donor and recipient were ABO compatible and immunosuppressive treatment was started with cyclosporine, mizoribine, and methylprednisolone. No acute rejection was experienced and histological acute rejection was not proven on any subsequent protocol biopsies. Ten yr after transplantation, a protocol biopsy revealed moderate chronic allograft nephropathy and severe cyclosporine-associated arteriolopathy. His allograft function was preserved at this time and the cyclosporine dose was tapered to 125 mg/d. His renal function gradually deteriorated starting 12 yr after transplantation. Although mizoribine was changed to mycophenolate mofetil, he required dialysis one yr later. A diagnosis of antibody-mediated rejection was made based upon the renal biopsy findings (including C4d staining) and circulating anti-human leukocyte antigen (HLA) antibody levels (12 yr after transplantation). We conclude that it is necessary to pay attention to antibody-mediated rejection, even in allograft cases with good function for over 10 yr and no risk factors for the development of de novo anti-HLA antibodies.     

Acute humoral rejection in kidney transplantation: II. Morphology, immunopathology, and pathologic classification

The incidence of acute humoral rejection (AHR) in renal allograft biopsies has been difficult to determine because widely accepted diagnostic criteria have not been established. C4d deposition in peritubular capillaries (PTC) of renal allografts has been proposed as a useful marker for AHR. This study was designed to test the relative value of C4d staining, histology, and serology in the diagnosis of AHR. Of 232 consecutive kidney transplants performed at a single institution from July 1995 to July 1999, all patients (n = 67) who developed acute rejection within the first 3 mo and had a renal biopsy with available frozen tissue at acute rejection onset, as well as posttransplant sera within 30 d of the biopsy, were included in this study. Hematoxylin and eosin and periodic acid-Schiff stained sections were scored for glomerular, vascular, and tubulointerstitial pathology. C4d staining of cryostat sections was done by a sensitive three-layer immunofluorescence method. Donor-specific antibodies (DSA) were detected in posttransplant recipient sera using antihuman-globulin-enhanced T cell and B cell cytotoxicity assays and/or flow cytometry. Widespread C4d staining in PTC was present in 30% (20 of 67) of all acute rejection biopsies. The initial histologic diagnoses of the C4d(+) acute rejection cases were as follows: AHR only, 30%; acute cellular rejection (ACR) and AHR, 45%; ACR (CCTT types 1 or 2) alone, 15%; and acute tubular injury (ATI), 10%. The distinguishing morphologic features in C4d(+) versus C4d(-) acute rejection cases included the following: neutrophils in PTC, 65% versus 9%; neutrophilic glomerulitis, 55% versus 4%; neutrophilic tubulitis, 55% versus 9%; severe ATI, 75% versus 9%; and fibrinoid necrosis in glomeruli, 20% versus 0%, or arteries, 25% versus 0%; all P < 0.01. Mononuclear cell tubulitis was more common in the C4d(-) group (70% versus 100%; P < 0.01). No significant difference between C4d(+) and C4d(-) acute rejection was noted for endarteritis, 25% versus 32%; interstitial inflammation (mean % cortex), 27.2 +/- 27% versus 38 +/- 21%; interstitial hemorrhage, 25% versus 15%; or infarcts, 5% versus 2%. DSA were present in 90% (18 of 20) of the C4d(+) cases compared with 2% (1 of 47) in the C4d(-) acute rejection cases (P < 0.001). The pathology of the C4d(+) but DSA(-) cases was not distinguishable from the C4d(+), DSA(+) cases. The C4d(+) DSA(-) cases may be due to non-HLA antibodies or subthreshold levels of DSA. The sensitivity of C4d staining is 95% in the diagnosis of AHR compared with the donor-specific antibody test (90%). Overall, eight grafts were lost to acute rejection in the first year, of which 75% (6 of 8) had AHR. The 1-yr graft failure rate was 27% (4 of 15) for those AHR cases with only capillary neutrophils versus 40% (2 of 5) for those who also had fibrinoid necrosis of arteries. In comparison, the 1-yr graft failure rates were 3% and 7%, respectively, in ACR 1 (Banff/CCTT type 1) and ACR 2 (Banff/CCTT type 2) C4d(-) groups. A substantial fraction (30%) of biopsy-confirmed acute rejection episodes have a component of AHR as judged by C4d staining; most (90%), but not all, have detectable DSA. AHR may be overlooked in the presence of ACR or ATI by histology or negative serology, arguing for routine C4d staining of renal allograft biopsies. Because AHR has a distinct therapy and prognosis, we propose that it should be classified separately from ACR, with further sub-classification into AHR 1 (neutrophilic capillary involvement) and AHR 2 (arterial fibrinoid necrosis).     

Evaluation of efficacy and safety of mycophenolate sodium in patients with de novo and maintenance renal transplantation: results of a multicenter, prospective, observational study

Objective

This study evaluates the effect of enteric-coated mycophenolate sodium (EC-MPS) on patient and graft survivals, the incidence of rejection episodes, and graft function among de novo and maintenance renal transplant recipients.

Patients and Methods

This open label, multicenter, prospective, post-marketing observational study of 470 renal transplantation patients at 23 centers in Turkey includes 331 de novo patients whose mean age was 29.6 ± 13.2 years and 139 maintenance patients of 34.0 ± 13.0 years. The latter subjects had EC-MPS substituted for mycophenolate mofetil or added to the immunosuppressive therapy. Patients were followed for 12 months to evaluate graft function and treatment failure.

Results

The most common primary disease requiring transplantation was glomerulonephritis (24.3%). De novo and maintenance groups were similar in terms of overall rejection rates and acute rejection incidence whereas chronic rejection was evident only among the latter cohort (P < 0.001). Time to an acute rejection episode was significantly longer among maintenance rather than de novo patients (220.8 versus 18.7 months; P = 0.015). Overall, 12 and 36 month survival rates were 91.6 ± 1.3% and 86.9% ± 0.3% among subjects experiencing acute rejection versus 99.7 ± 0.2% and 50.3% for those displaying chronic rejection. Among maintenance group no deterioration of renal function was observed after conversion from mycophenolate mofetil to EC-MPS. The incidences of leukopenia, new-onset anemia, or liver dysfunction were similar between de novo and maintenance patients. Gastrointestinal discomfort was more prevalent among the maintenance group, reaching a significant level at the fourth visit (P < 0.05). EC-MPS dose reduction was required in only 16.7% of patients at visit, it was more frequent among the de novo group (17.9 versus 13.8%).

Conclusion

EC-MPS was an effective adjunctive therapy for de novo as well as maintenance renal transplant recipients in the Turkish population due to a relatively low incidence of dose reductions necessitated by adverse events as well as with an increased likelihood of long-term graft survival.     

Anti-Hla donor-specific antibody monitoring in pancreas transplantation: Role of protocol biopsies

In kidney transplantation, de novo donor-specific antibodies (DSA) correlate with poor graft survival, and Consensus Guidelines recommend a protocol biopsy. In pancreas transplantation, DSA are also associated with poor graft outcomes; however, there are no recommendations on protocol biopsies. We started an antibody screening protocol on pancreas transplant patients at 0, 3, 6, 12 months, and yearly. Patients with DSA or high MFI non-DSA were considered for protocol biopsies of both organs. Results: 143 pancreas recipients were screened. 84 patients had negative antibodies throughout the study, 11 patients were found to have antibodies at graft dysfunction, and 48 patients had positive antibodies at screening without acute organ dysfunction (study group). Among the 30 non-DSA patients, 9 had protocol simultaneous pancreas and kidney biopsies performed with negative results in all of them. In contrast, among the 18 DSA patients, 15 had these biopsies performed, and 47% presented with subclinical rejection of the kidney, the pancreas, or both. In addition, some of the DSA patients without a protocol biopsy presented with rejection during the first 15 months of follow-up. Conclusion: We conclude that protocol biopsies of both grafts may play a role in the follow-up of pancreas transplant patients with de novo DSA appearance.