Banff 2013 meeting report: inclusion of c4d-negative antibody-mediated rejection and antibody-associated arterial lesions

Outcomes Following ABO-Incompatible Kidney Transplantation Performed After Desensitization by Nonantigen-Specific Immunoadsorption

BACKGROUND

For desensitization of ABO-incompatible kidney transplant recipients we recently proposed nonantigen-specific immunoadsorption (IA) and rituximab.

METHODS

We now compared clinical outcomes of 34 ABO-incompatible living-donor kidney recipients who were transplanted using this protocol with that of 68 matched ABO-compatible patients. In addition, we analyzed efficacy and cost of nonantigen-specific as compared to blood group antigen-specific IA.

RESULTS

Before desensitization, the median isoagglutinin titer of 34 ABO-incompatible patients was 1:64 (Coombs technique). Patients received a median of 7 preoperative IA treatments. Twenty-four patients had a median of 2 additional plasmapheresis treatments to reach the preoperative target isoagglutinin titer of 1:8 or less. After a median postoperative follow-up of 22 months, overall graft survival in the ABO-incompatible group was not significantly different from that in ABO-compatible patients (log-rank P = 0.20), whereas patient survival tended to be lower (log-rank P = 0.05). The incidence of rejection episodes was 15% in both groups. The ABO-incompatible kidney recipients had a higher incidence of BK virus replication (P = 0.04) and nephropathy (P = 0.01) and showed more often colonization with multidrug resistant bacteria (P = 0.02). In comparison to blood group antigen-specific IA, nonantigen-specific IA showed equal efficacy but was associated with reduction in cost.

CONCLUSIONS

Clinical outcomes of ABO-incompatible patients desensitized with a nonantigen-specific IA device and rituximab do not differ from that of matched ABO-compatible patients although a trend toward reduced patient survival was noted. Special attention must be paid to the higher incidence of BK virus infection in recipients of ABO-incompatible grafts.

Decreased chronic cellular and antibody-mediated injury in the kidney following simultaneous liver-kidney transplantation

In simultaneous liver-kidney transplantation (SLK), the liver can protect the kidney from hyperacute rejection and may also decrease acute cellular rejection rates. Whether the liver protects against chronic injury is unknown. To answer this we studied renal allograft surveillance biopsies in 68 consecutive SLK recipients (14 with donor-specific alloantibodies at transplantation [DSA+], 54 with low or no DSA, [DSA-]). These were compared with biopsies of a matched cohort of kidney transplant alone (KTA) recipients (28 DSA+, 108 DSA-). Overall 5-year patient and graft survival was not different: 93.8% and 91.2% in SLK, and 91.9% and 77.1% in KTA. In DSA+ recipients, KTA had a significantly higher incidence of acute antibody-mediated rejection (46.4% vs. 7.1%) and chronic transplant glomerulopathy (53.6% vs. 0%). In DSA- recipients at 5 years, KTA had a significantly higher cumulative incidence of T cell-mediated rejection (clinical plus subclinical, 30.6% vs. 7.4%). By 5 years, DSA+ KTA had a 44% decline in mean GFR while DSA+SLK had stable GFR. In DSA- KTA, the incidence of a combined endpoint of renal allograft loss or over a 50% decline in GFR was significantly higher (20.4% vs. 7.4%). Simultaneously transplanted liver allograft was the most predictive factor for a significantly lower incidence of cellular (odds ratio 0.13, 95% confidence interval 0.06-0.27) and antibody-mediated injury (odds ratio 0.11, confidence interval 0.03-0.32), as well as graft functional decline (odds ratio 0.22, confidence interval 0.06-0.59). Thus, SLK is associated with reduced chronic cellular and antibody-mediated alloimmune injury in the kidney allograft.

IL-10-produced by human transitional B-cells down-regulates CD86 expression on B-cells leading to inhibition of CD4+T-cell responses

A novel subset of human regulatory B-cells has recently been described. They arise from within the transitional B-cell subpopulation and are characterised by the production of IL-10. They appear to be of significant importance in regulating T-cell immunity in vivo. Despite this important function, the molecular mechanisms by which they control T-cell activation are incompletely defined. Here we show that transitional B-cells produced more IL-10 and expressed higher levels of IL-10 receptor after CD40 engagement compared to other B-cell subsets. Furthermore, under this stimulatory condition, CD86 expressed by transitional B-cells was down regulated and T-cell proliferation was reduced. We provide evidence to demonstrate that the down-regulation of CD86 expression by transitional B-cells was due to the autocrine effect of IL-10, which in turn leads to decreased T-cell proliferation and TNF-α production. This analysis was further extended to peripheral B-cells in kidney transplant recipients. We observed that B-cells from patients tolerant to the graft maintained higher IL-10 production after CD40 ligation, which correlates with lower CD86 expression compared to patients with chronic rejection. Hence, the results obtained in this study shed light on a new alternative mechanism by which transitional B-cells inhibit T-cell proliferation and cytokine production.

Relationships among injury, fibrosis, and time in human kidney transplants

BACKGROUND

Kidney transplant biopsies offer an opportunity to understand the pathogenesis of organ fibrosis. We studied the relationships between the time of biopsy after transplant (TxBx), histologic fibrosis, diseases, and transcript expression.

METHODS

Expression microarrays from 681 kidney transplant indication biopsies taken either early (n = 282, <1 year) or late (n = 399, >1 year) after transplant were used to analyze the molecular landscape of fibrosis in relationship to histologic fibrosis and diseases.

RESULTS

Fibrosis was absent at transplantation but was present in some early biopsies by 4 months after transplant, apparently as a self-limited response to donation implantation injury not associated with progression to failure. The molecular phenotype of early biopsies represented the time sequence of the response to wounding: immediate expression of acute kidney injury transcripts, followed by fibrillar collagen transcripts after several weeks, then by the appearance of immunoglobulin and mast cell transcripts after several months as fibrosis appeared. Fibrosis in late biopsies correlated with injury, fibrillar collagen, immunoglobulin, and mast cell transcripts, but these were independent of time. Pathway analysis revealed epithelial response-to-wounding pathways such as Wnt/β-catenin.

CONCLUSION

Fibrosis in late biopsies had different associations because many kidneys had potentially progressive diseases and subsequently failed. Molecular correlations with fibrosis in late biopsies were independent of time, probably because ongoing injury obscured the response-to-wounding time sequence. The results indicate that fibrosis in kidney transplants is driven by nephron injury and that progression to failure reflects continuing injury, not autonomous fibrogenesis.

TRIAL REGISTRATION

INTERCOM study (www.clinicalTrials.gov; NCT01299168).

FUNDING

Canada Foundation for Innovation and Genome Canada.

Diffusion-Weighted imaging and diffusion tensor imaging detect delayed graft function and correlate with allograft fibrosis in patients early after kidney transplantation

PURPOSE

To combine diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) for detection of allograft dysfunction in patients early after kidney transplantation and to correlate diffusion parameters with renal function and renal histology of allograft biopsies.

MATERIALS AND METHODS

Between day 4 and 11 after kidney transplantation 33 patients with initial graft function and 31 patients with delayed graft function (DGF) were examined with a 1.5T magnetic resonance imaging (MRI) scanner. DTI and DWI sequences were acquired and fractional anisotropy (FA), apparent diffusion coefficient (ADCmono), pure diffusion (ADCdiff ), and the perfusion fraction (Fp) were calculated. Kidney biopsies in 26 patients were analyzed for allograft pathology, ie, acute tubular injury, inflammation, edema, renal fibrosis, and rejection. Histological results were correlated with MRI parameters.

RESULTS

In the renal medulla FA (0.25 ± 0.06 vs. 0.29 ± 0.06, P < 0.01) and ADCmono (1.73 ± 0.13*10(-3) vs. 1.93 ± 0.16*10(-3) mm(2) /s, P < 0.001) were significantly reduced in DGF patients compared with patients with initial function. For ADCdiff and Fp similar reductions were observed. FA and ADCmono significantly correlated with renal function (r = 0.53 and r = 0.57, P < 0.001) and were inversely correlated with the amount of renal fibrosis (r = -0.63 and r = -0.65, P < 0.05).

CONCLUSION

Combined DTI and DWI detected allograft dysfunction early after kidney transplantation and correlated with allograft fibrosis. J. Magn. Reson. Imaging 2016;44:112-121.

A Preliminary Study Into the Significance of Intrarenal Reflux in BK Virus Nephropathy After Kidney Transplantation

Background

The BK virus typically colonizes the lower urinary tract and is the causative agent in BK virus nephropathy (BKVN), which can progress to allograft dysfunction and graft loss. Urinary reflux in kidney allografts is induced by vesicoureteral reflux or disturbances in intrarenal reflux (IRR), believed to be associated with BKVN. This study was designed to elucidate the relationship between BKVN and IRR.

Methods

We examined 30 renal transplant recipients histologically diagnosed with BKVN using anti-Simian virus 40 immunohistochemistry and 60 clinically matched control recipients. The BKVN patients were divided into stable (n = 12) and progressive (n = 18) groups according to allograft kidney function 1 year after diagnosis. Histological rejection scores according to the pathological classification of rejection in renal allografts (Banff classification), histological BKVN stages, and histological polyomavirus load levels (pvl) proposed by the Banff working group were evaluated. The IRR was quantified by histological reflux scores defined with retention and reflux of immunostained Tamm-Horsfall protein in renal tubules and glomeruli.

Results

Higher reflux scores were observed in the BKVN group compared with that in the control group. No differences in clinical parameters were observed between the BKVN and control groups. Reflux scores and pvl were significantly higher in the progressive group than in the stable BKVN group with no significant difference in BK stage observed between groups. Reflux scores were found to be significantly correlated with pvl.

Conclusions

Our preliminary study suggested that IRR might be a predisposing and prognostic factor in BKVN.

Endothelial activation, lymphangiogenesis, and humoral rejection of kidney transplants

Antibody-mediated rejection (ABMR) is implicated in 45% of renal allograft failure and 57% of late allograft dysfunction. Peritubular capillary C4d is a specific but insensitive marker of ABMR. The 2013 Banff Conference ABMR revised criteria included C4d-negative ABMR with evidence of endothelial-antibody interaction. We hypothesized that endothelial activation and lymphangiogenesis are increased with C4d-negative ABMR and correlate with intragraft T-regulatory cells and T-helper 17. Seventy-four renal transplant biopsies were selected to include (a) ABMR with C4d Banff scores ≥2 (n = 35), (b) variable microvascular injury and C4d score 0-1 (n = 24), and (c) variable microvascular injury and C4d score = 0 (n = 15). Controls included normal preimplantation donor kidneys (n = 5). Immunohistochemistry for endothelial activation (P- and E-selectins [SEL]), lymphangiogenesis (D2-40), T-regulatory cells (FOXP3), and T-helper 17 (STAT3) was performed. Microvessel and inflammatory infiltrate density was assessed morphometrically in interstitium and peritubular capillaries. All transplants had significantly higher microvessel and lymph vessel density compared with normal. Increased expression of markers of endothelial activation predicted transplant glomerulopathy (P-SEL, P = .003). Increased P-SEL and D2-40 were associated with longer interval from transplant to biopsy (P = .005). All 3 markers were associated with increased interstitial fibrosis, tubular atrophy, and graft failure (P-SEL, P < .001; E-SEL, P = .0011; D2-40, P = .012). There was no association with the intragraft FOXP3/STAT3 ratio. We conclude that endothelial activation and lymphangiogenesis could represent a late response to injury leading to fibrosis and progression of kidney damage, and are independent of the intragraft FOXP3/STAT3 ratio. Our findings support the therapeutic potential of specifically targeting endothelial activation.

Practical Applications in Immunohistochemistry: Evaluation of Rejection and Infection in Organ Transplantation

CONTEXT

-Immunohistochemical analysis of tissue biopsy specimens is a crucial tool in diagnosis of both rejection and infection in patients with solid organ transplants. In the past 15 years, the concept of antibody-mediated rejection has been refined, and diagnostic criteria have been codified in renal, heart, pancreas, and lung allografts (with studies ongoing in liver, small intestine, and composite grafts), all of which include immunoanalysis for the complement split product C4d.

OBJECTIVES

-To review the general concepts of C4d biology and immunoanalysis, followed by organ-allograft-specific data, and interpretative nuances for kidney, pancreas, and heart, with discussion of early literature for lung and liver biopsies. Additionally, practical applications and limitations of immunostains for infectious organisms (Polyomavirus, Adenoviridae [adenovirus], and the herpes virus family, including Herpes simplex virus, Cytomegalovirus, Human herpes virus 8, and Epstein-Barr virus) are reviewed in the context of transplant recipients.

DATA SOURCES

-Our experience and published primary and review literature.

CONCLUSIONS

-Immunohistochemistry continues to have an important role in transplant pathology, most notably C4d staining in assessment of antibody-mediated rejection and assessment of viral pathogens in tissue. In all facets of transplant pathology, correlation of morphology with special studies and clinical data is critical, as is close communication with the transplant team.

The inferior impact of antibody-mediated rejection on the clinical outcome of kidney allografts that develop de novo thrombotic microangiopathy

BACKGROUND

Antibody-mediated rejection (AMR) can induce and develop thrombotic microangiopathy (TMA) in renal allografts. A definitive AMR (dAMR) co-presents three diagnostic features. A suspicious AMR (sAMR) is designated when one of the three features is missing.

METHODS

Thirty-two TMA cases overlapping with AMR (AMR+ TMA) were studied, which involved 14 cases of sAMR+ TMA and 18 cases of dAMR+ TMA. Thirty TMA cases free of AMR features (AMR- TMA) were enrolled as control group.

RESULTS

The ratio of complete response to treatment was similar between AMR- TMA and AMR+ TMA group (23.3% vs. 12.5%, p = 0.33), or between sAMR+ TMA and dAMR+ TMA group (14.3% vs. 11.1%, p = 0.79). At eight yr post-transplantation, the death-censored graft survival (DCGS) rate of AMR- TMA group was 62.8%, which was significantly higher than 28.0% of AMR+ TMA group (p = 0.01), but similar between sAMR+ TMA and dAMR+ TMA group (30.0% vs. 26.7%, p = 0.92). Overall, the intimal arteritis and the broad HLA (Human leukocyte antigens) mismatches were closely associated with over time renal allograft failure.

CONCLUSION

The AMR+ TMA has inferior long-term graft survival, but grafts with sAMR+ TMA or dAMR+ TMA have similar characteristics and clinical courses.

The prevalence and clinical significance of C1q-binding donor-specific anti-HLA antibodies early and late after kidney transplantation

We aimed to determine the prevalence and clinical significance of complement-binding donor-specific antibodies (DSA) detected up to 30 years after kidney transplantation. Group 1 patients included 284 consecutive DSA negative patients who underwent kidney transplantation after 1 May 2009. Group 2 included 405 patients transplanted before this date and followed at our center with functioning allografts. DSA were tested using Luminex Single Antigen and the C1q assay. In Group 1 patients, who were monitored prospectively, 31 (11%) developed de novo DSA during a median follow-up of 2.5 (1.9, 3.6) years. Of these, 11 (4%) had C1q+ and 20 (7%) had C1q negative DSA. In Group 2 patients, 77 (19%) displayed DSA. Among these, 33 (8%) had C1q+ and 44 (11%) had C1q negative DSA. The incidence of acute antibody-mediated rejection (AMR) was significantly higher in C1q+DSA patients in both Group 1 (45%) and Group 2 (15%) compared with C1q negative DSA (5% and 2%) and DSA negative patients (1% and 3%; P < 0.001 and P = 0.001). The incidence of chronic AMR was 36% (Group 1) and 51% (Group 2) in patients with C1q+DSA. In contrast, chronic AMR occurred in 5% and 25% of C1q negative DSA, and 2% and 6% of DSA negative Group 1 and 2 patients, respectively (P < 0.001). Although the graft survival was lower in Group 1 C1q+DSA patients (73%) compared with C1q negative DSA (95%) and DSA negative (94%) patients, the difference was not statistically significant by Kaplan-Meier survival analysis (P = 0.21). Our results indicated that the presence of C1q+ DSA was associated with acute and chronic AMR.

Translational implications of endothelial cell dysfunction in association with chronic allograft rejection

Advances in therapeutics have dramatically improved short-term graft survival, but the incidence of chronic rejection has not changed in the past 20 years. New insights into mechanism are sorely needed at this time and it is hoped that the development of predictive biomarkers will pave the way for the emergence of preventative therapeutics. In this review, we discuss a paradigm suggesting that sequential changes within graft endothelial cells (EC) lead to an intragraft microenvironment that favors the development of chronic rejection. Key initial events include EC injury, activation and uncontrolled leukocyte-induced angiogenesis. We propose that all of these early changes in the microvasculature lead to abnormal blood flow patterns, local tissue hypoxia, and an associated overexpression of HIF-1α-inducible genes, including vascular endothelial growth factor. We also discuss how cell intrinsic regulators of mTOR-mediated signaling within EC are of critical importance in microvascular stability and may thus have a role in the inhibition of chronic rejection. Finally, we discuss recent findings indicating that miRNAs may regulate EC stability, and we review their potential as novel non-invasive biomarkers of allograft rejection. Overall, this review provides insights into molecular events, genes, and signals that promote chronic rejection and their potential as biomarkers that serve to support the future development of interruption therapeutics.

Changing Kidney Allograft Histology Early Posttransplant: Prognostic Implications of 1-Year Protocol Biopsies

Allograft histology 1 year posttransplant is an independent correlate to long-term death-censored graft survival. We assessed prognostic implications of changes in histology first 2 years posttransplant in 938 first kidney recipients, transplanted 1999-2010, followed for 93.4 ± 37.7 months. Compared to implantation biopsies, histology changed posttransplant showing at 1 year that 72.6% of grafts had minor abnormalities (favorable histology), 20.2% unfavorable histology, and 7.2% glomerulonephritis. Compared to favorable, graft survival was reduced in recipients with unfavorable histology (hazards ratio [HR] = 4.79 [3.27-7.00], p < 0.0001) or glomerulonephritis (HR = 5.91 [3.17-11.0], p < 0.0001). Compared to unfavorable, in grafts with favorable histology, failure was most commonly due to death (42% vs. 70%, p < 0.0001) and less commonly due to alloimmune causes (27% vs. 10%, p < 0.0001). In 80% of cases, favorable histology persisted at 2 years. However, de novo 2-year unfavorable histology (15.3%) or glomerulonephritis (4.7%) related to reduced survival. The proportion of favorable grafts increased during this period (odds ratio = 0.920 [0.871-0.972], p = 0.003, per year) related to fewer DGF, rejections, polyoma-associated nephropathy (PVAN), and better function. Graft survival also improved (HR = 0.718 [0.550-0.937], p = 0.015) related to better histology and function. Evolution of graft histologic early posttransplant relate to long-term survival. Avoiding risk factors associated with unfavorable histology relates to improved histology and graft survival.

Fluorodeoxyglucose F(18) Positron Emission Tomography Coupled With Computed Tomography in Suspected Acute Renal Allograft Rejection

Management of kidney transplant recipients (KTRs) with suspected acute rejection (AR) ultimately relies on kidney biopsy; however, noninvasive tests predicting nonrejection would help avoid unnecessary biopsy. AR involves recruitment of leukocytes avid for fluorodeoxyglucose F(18) ((18) F-FDG), thus (18) F-FDG positron emission tomography (PET) coupled with computed tomography (CT) may noninvasively distinguish nonrejection from AR. From January 2013 to February 2015, we prospectively performed 32 (18) F-FDG PET/CT scans in 31 adult KTRs with suspected AR who underwent transplant biopsy. Biopsies were categorized into four groups: normal (n = 8), borderline (n = 10), AR (n = 8), or other (n = 6, including 3 with polyoma BK nephropathy). Estimated GFR was comparable in all groups. PET/CT was performed 201 ± 18 minutes after administration of 3.2 ± 0.2 MBq/kg of (18) F-FDG, before any immunosuppression change. Mean standard uptake values (SUVs) of both upper and lower renal poles were measured. Mean SUVs reached 1.5 ± 0.2, 1.6 ± 0.3, 2.9 ± 0.8, and 2.2 ± 1.2 for the normal, borderline, AR, and other groups, respectively. One-way analysis of variance demonstrated a significant difference of mean SUVs among groups. A positive correlation between mean SUV and acute composite Banff score was found, with r(2)  = 0.49. The area under the receiver operating characteristic curve was 0.93, with 100% sensitivity and 50% specificity using a mean SUV threshold of 1.6. In conclusion, (18) F-FDG PET/CT may help noninvasively prevent avoidable transplant biopsies in KTRs with suspected AR.

Presentation and Outcomes of C4d-Negative Antibody-Mediated Rejection After Kidney Transplantation

The updated Banff classification allows for the diagnosis of antibody-mediated rejection (AMR) in the absence of peritubular capillary C4d staining. Our objective was to quantify allograft loss risk in patients with consistently C4d-negative AMR (n = 51) compared with C4d-positive AMR patients (n = 156) and matched control subjects without AMR. All first-year posttransplant biopsy results from January 2004 through June 2014 were reviewed and correlated with the presence of donor-specific antibody (DSA). C4d-negative AMR patients were not different from C4d-positive AMR patients on any baseline characteristics, including immunologic risk factors (panel reactive antibody, prior transplant, HLA mismatch, donor type, DSA class, and anti-HLA/ABO-incompatibility). C4d-positive AMR patients were significantly more likely to have a clinical presentation (85.3% vs. 54.9%, p < 0.001), and those patients presented substantially earlier posttransplantation (median 14 [interquartile range 8-32] days vs. 46 [interquartile range 20-191], p < 0.001) and were three times more common (7.8% vs 2.5%). One- and 2-year post-AMR-defining biopsy graft survival in C4d-negative AMR patients was 93.4% and 90.2% versus 86.8% and 82.6% in C4d-positive AMR patients, respectively (p = 0.4). C4d-negative AMR was associated with a 2.56-fold (95% confidence interval, 1.08-6.05, p = 0.033) increased risk of graft loss compared with AMR-free matched controls. No clinical characteristics were identified that reliably distinguished C4d-negative from C4d-positive AMR. However, both phenotypes are associated with increased graft loss and thus warrant consideration for intervention.

Recurrent Membranous Nephropathy After Kidney Transplantation: Treatment and Long-Term Implications

BACKGROUND

Membranous nephropathy (MN) can recur in kidney allografts leading to graft dysfunction and failure. The aims of these analyses were to assess MN recurrence, clinical and histologic progression, and response to anti-CD20 therapy.

METHODS

Included were 63 kidney allograft recipients with biopsy proven primary MN followed up for 77.0 (39-113) months (median, interquartile range). Disease recurrence was diagnosed by biopsy (protocol or clinical), and follow-up was monitored by laboratory parameters and protocol biopsies.

RESULTS

Thirty of 63 patients (48%) had histologic recurrence often during the first year. In 53% of the cases, recurrence was diagnosed by protocol biopsy. Recurrence risk was higher in patients with higher proteinuria pretransplant [hazard ratio = 1.869 (95% confidence interval, 1.164-3.001) per gram, P = 0.010] and those with anti-phospholipase A2 receptor antibodies [hazard ratio = 3.761 (1.635-8.652), P = 0.002]. Thirteen patients with recurrence had no clinical progression, and in 2, MN resolved histologically. Seventeen of 63 patients (27%) had progressive proteinuria and were treated with anti-CD20 antibodies, resulting in complete response in 9 (53%), partial response in 5 (29%), and no response in 3 (18%). Posttreatment biopsies were obtained in 15 patients and showed histologic resolution in 6 (40%). Disease recurrence did not correlate with graft survival. However, 5 of 11 (45.4%) graft losses were due to recurrent MN. Death-censored graft survival in MN did not differ from that of 273 control recipients with autosomal dominant polycystic kidney disease.

CONCLUSIONS

Membranous nephropathy recurs in 48% of cases threatening the allograft. Treatment of early but progressive recurrence with anti-CD20 antibodies is quite effective achieving clinical remission and histologic resolution of MN.

Characterisation of Tertiary Lymphoid Organs in Explanted Rejected Donor Kidneys

PURPOSE

Tertiary lymphoid organs (TLOs) have been described within organ allografts, but whether they promote destructive or beneficial alloimmune responses remains controversial. This study aimed to characterize TLO distribution in human chronically rejected renal allografts and to explore their functions.

METHODS

A total of 29 explanted chronically rejected and 12 acutely rejected renal allografts were analyzed by immunohistochemistry. The distribution of TLOs, T cells, follicular dendritic cells, B cells, and follicular regulatory T (Tfr) cells, as well as Ki67, peripheral lymph node addressin (PNAd), podoplanin, AID, IL-17, IL-21, IL-10, and C4d expression were detected by immunohistochemistry. Correlations between lymphoid neogenesis and the expression of IL-17, IL-21, C4d, podoplanin, IL-10, and Foxp3 were evaluated. In addition, the duration of graft function was compared between allografts that harbored or lacked TLOs.

RESULTS

TLOs were detected in 27.6% of chronically rejected renal grafts, but they rarely had germinal centers. Lymphoid neogenesis negatively correlated with CXCR5 expression, and almost completely correlated with IL-17 expression. Those grafts that harbored a TLO functioned for an average of 5.98 years and those without a TLO lasted only about half as long with an average of 2.91 years. However, in grafts that harbored a TLO, Foxp3(+) cells were comparitively less than those without a TLO. Foxp3(+)CXCR5(+) Tfr cells and IL-10(+) cells were rare in grafts, irrespective of the presence of a TLO.

CONCLUSION

TLOs in chronically rejected kidney allografts may be an epiphenomenon of the inflammatory process that is related to graft duration.

Clinical and pathological features of kidney transplant patients with concurrent polyomavirus nephropathy and rejection-associated endarteritis

AIM: To describe the clinicopathologic features of concurrent polyomavirus nephropathy (PVN) and endarteritis due to rejection in renal allografts.

METHODS: We searched our electronic records database for cases with transplant kidney biopsies demonstrating features of both PVN and acute rejection (AR). PVN was defined by the presence of typical viral cytopathic effect on routine sections and positive polyomavirus SV40 large-T antigen immunohistochemistry. AR was identified by endarteritis (v1 by Banff criteria). All cases were subjected to chart review in order to determine clinical presentation, treatment course and outcomes. Outcomes were recorded with a length of follow-up of at least one year or time to nephrectomy.

RESULTS: Of 94 renal allograft recipients who developed PVN over an 11-year period at our institution, we identified 7 (7.4%) with viral cytopathic changes, SV40 large T antigen staining, and endarteritis in the same biopsy specimen, indicative of concurrent PVN and AR. Four arose after reduction of immunosuppression (IS) (for treatment of PVN in 3 and tuberculosis in 1), and 3 patients had no decrease of IS before developing simultaneous concurrent disease. Treatment consisted of reduced oral IS and leflunomide for PVN, and anti-rejection therapy. Three of 4 patients who developed endarteritis in the setting of reduced IS lost their grafts to rejection. All 3 patients with simultaneous PVN and endarteritis cleared viremia and were stable at 1 year of follow up. Patients with endarteritis and PVN arising in a background of reduced IS had more severe rejection and poorer outcome.

CONCLUSION: Concurrent PVN and endarteritis may be more frequent than is currently appreciated and may occur with or without prior reduction of IS.

Intragraft Blood Dendritic Cell Antigen-1-Positive Myeloid Dendritic Cells Increase during BK Polyomavirus-Associated Nephropathy

Although both polyomavirus infection and T cell-mediated rejection (TCMR) are characterized by tubulointerstitial inflammation in the renal allograft, these conditions are treated with opposing therapeutic regimens. To gain more insight into the differences between antiviral and alloimmune responses, we performed a case-control study, in which we immunophenotyped the inflammatory infiltrates in renal biopsy specimens with BK polyomavirus-associated nephropathy (BKPyVAN) and specimens with TCMR. Compared with TCMR, BKPyVAN was diagnosed later after transplantation; therefore, BKPyVAN specimens showed more chronic damage than TCMR specimens showed. However, TCMR and BKPyVAN specimens had comparable levels of tubulointerstitial inflammation. Adjustment for confounders in various multivariable models revealed more blood dendritic cell antigen-1(+) (BDCA-1(+)) myeloid dendritic cells (mDCs) present during BKPyVAN (odds ratio, 2.31; 95% confidence interval, 1.03 to 5.16; P=0.04) than during TCMR. Double immunostaining for SV40 and BDCA-1 showed that, during BKPyVAN, BDCA-1(+) mDCs localized in proximity to the polyomavirus-infected tubular epithelial cells. We ensured that time of biopsy after transplantation was not a confounding factor by including additional specimens with late TCMR and protocol biopsy specimens matched for biopsy time. These additional specimens showed amounts of BDCA-1(+) mDCs comparable with amounts in the early TCMR specimens. These results suggest that BDCA-1(+) mDCs, known to be involved in the antiviral immune response during various viral infections, might have a pivotal role during BKPyVAN infection in the grafted kidney.

Angiotensin II type 1 receptor antibody precipitating acute vascular rejection in kidney transplantation

Atypical non HLA antibodies are increasingly recognised as causes of immunological injury in allotransplantation. In this report we describe a non HLA sensitized male renal allograft recipient who developed acute vascular rejection on a "for cause" biopsy (Banff v2, g2, ptc 3) at day 4 post first renal allograft in the presence of elevated angiotensin II type 1 receptor antibodies (AT1R-Ab level 14.1). The acute rejection was treated with pulse corticosteroid therapy, anti-thymocyte globulin (ATG × 6), plasma exchange (1.5 plasma volume replacement x6) and oral candesartan. Serum creatinine improved and follow up biopsy confirmed resolution of rejection following treatment. AT1R-Ab should be considered when rejection is diagnosed in the absence of HLA antibodies.

Benefits of a transfer clinic in adolescent and young adult kidney transplant patients

Background

Adolescent and young adult kidney transplant recipients have worse graft outcomes than older and younger age groups. Difficulties in the process of transition, defined as the purposeful, planned movement of adolescents with chronic health conditions from child to adult-centered health care systems, may contribute to this. Improving the process of transition may improve adherence post-transfer to adult care services.

Objective

The purpose of this study is to investigate whether a kidney transplant transfer clinic for adolescent and young adult kidney transplant recipients transitioning from pediatric to adult care improves adherence post-transfer.

Methods

We developed a joint kidney transplant transfer clinic between a pediatric kidney transplant program, adult kidney transplant program, and adolescent medicine at two academic health centers. The transfer clinic facilitated communication between the adult and pediatric transplant teams, a face-to-face meeting of the patient with the adult team, and a meeting with the adolescent medicine physician. We compared the outcomes of 16 kidney transplant recipients transferred before the clinic was established with 16 patients who attended the clinic. The primary outcome was a composite measure of non-adherence. Non-adherence was defined as either self-reported medication non-adherence or displaying two of the following three characteristics: non-attendance at clinic, non-attendance for blood work appointments, or undetectable calcineurin inhibitor levels within 1 year post-transfer.

Results

The two groups were similar at baseline, with non-adherence identified in 43.75 % of patients. Non-adherent behavior in the year post-transfer, which included missing clinic visits, missing regular blood tests, and undetectable calcineurin inhibitor levels, was significantly lower in the cohort which attended the transfer clinic (18.8 versus 62.5 %, p = 0.03). The median change in estimated glomerular filtration rate (eGFR) in the year following transfer was smaller in the group that attended the transition clinic (−0.9 ± 13.2 ml/min/1.73 m²) compared to those who did not (−12.29 ± 14.9 ml/min/1.73 m²), p = 0.045.

Conclusions

Attendance at a single kidney transplant transfer clinic was associated with improved adherence and renal function in the year following transfer to adult care. If these changes are sustained, they may improve long-term graft outcomes for adolescent kidney transplant recipients.

The Banff Conferences on renal allograft pathology – the latest 2013 report

The Banff Conference diagnostic categories and their criteria for renal biopsy interpretation were created in 1991 by a group comprising nephrologists, pathologists, transplant surgeons and immunologists. These guidelines are widely used in many countries. Every two years, participants at these meetings present and discuss research findings that have added to our knowledge of allograft pathology. From the start, features of T-cell mediated rejection were established. This was followed by discovery of C4d staining in biopsy tissue and better characterisation of antibody mediated rejection. The formation of working groups to look into problematic areas has allowed better refinements to be made to the classification scheme. The latest Banff 2013 report is significant for the inclusion of a C4d-negative category under humoral rejection. Together with the realisation that endarteritis may be antibody mediated, this latest report will greatly impact how pathologists interpret the allograft biopsy.

Antibody-mediated Rejection in Lung Transplantation

There has been increasing awareness of antibody-mediated rejection (AMR) as an important cause of graft failure after lung transplantation in recent years. However, the diagnostic criteria for pulmonary AMR are not well defined. All four tenets of AMR in kidney and heart transplantation, graft dysfunction, complement component deposition, circulating donor-specific antibodies (DSA), and histopathologic changes consistent with AMR, are infrequently present in lung transplantation. Nonetheless, the lung transplant community has made important progress recognizing cases of AMR and developing a definition. However, AMR is often refractory to therapy resulting in graft failure and death. In this review, we discuss the progress and challenges in the diagnosis and therapeutic options for pulmonary AMR. In addition, we briefly examine emerging paradigms of C4d-negative AMR and chronic AMR, and conclude that significant progress is needed to mitigate the effects of humoral immune responses after lung transplantation.

Tubuloreticular Inclusions in Renal Allografts Associate with Viral Infections and Donor-Specific Antibodies

The presence of tubuloreticular inclusions (TRIs) in native glomerular endothelial cells associates with viral infections and lupus nephritis. However, the associations of TRIs in renal transplant biopsy specimens are not known. We analyzed data from 316 patients who had a transplant biopsy with electron microscopy examination; 41 of 316 (13.0%) patients had TRIs. Patients with TRIs had significantly lower allograft survival rates (50.9%) than patients without TRIs (74.3%; P=0.03). Transplant glomerulopathy-free survival was also inferior in the TRI-positive group (57.5%) compared with the TRI-negative group (87.3%; P=0.002). Serologically, hepatitis C associated with the presence of TRIs (P=0.04) along with donor-specific antibodies (P=0.01). Furthermore, patients who were TRI positive were more likely than patients who were TRI negative to have had a previous rejection episode (P=0.02). On multivariate analysis, TRIs associated with prior rejection, viral infections, and class 1 HLA donor-specific antibodies. These results show that the presence of TRIs in renal allograft biopsy specimens associates with poor allograft outcomes and serologic evidence of viral infections and alloimmunity. The association with alloimmunity is a novel finding that warrants additional investigation.

Advances in pharmacotherapy to treat kidney transplant rejection

INTRODUCTION

Current immunosuppressive combination therapy provides excellent prevention of T-cell-mediated rejection following renal transplantation; however, antibody-mediated rejection remains of high concern and accounts for a large number of long-term allograft losses. The recent development of protocol biopsies resulted in the definition of subclinical rejection (SCR), showing histologic evidence for rejection but unremarkable clinical course.

AREAS COVERED

This review describes the current knowledge and evidence of pharmacotherapy to treat kidney allograft rejections and covers SCR treatment options. Each substance is analyzed with regard to its classical indication and further discussed for the treatment of other forms of rejection.

EXPERT OPINION

Despite a lack of randomized trials, early acute T-cell-mediated rejection can be treated effectively in most cases without graft loss. The necessity to treat SCR is currently unclear. Due to a lack of effective therapies, new treatment approaches for antibody-mediated rejection are an urgent medical need to improve long-term outcomes. Future research should aim to better define pathophysiology and histology, stratify risk, and develop rational treatment strategies from randomized controlled trials, in order to establish the value of novel therapies in the arsenal of rejection pharmacotherapy. However, the effective prevention of rejection with minimal side effects still remains the goal in immunosuppression.

Clinical, Histological, and Molecular Markers Associated With Allograft Loss in Transplant Glomerulopathy Patients

BACKGROUND

We aimed to investigate the clinical, histopathological, and molecular factors associated with allograft loss in transplant glomerulopathy (TGP) patients.

METHODS

Of the 525 patients who underwent clinically indicated kidney biopsies, 52 (10%) had diagnosis of TGP. Gene expression profiles of 28 TGP and 11 normal transplant kidney biopsy samples were analyzed by Affymetrix HuGene 1.0 ST expression arrays.

RESULTS

Over a median follow up of 23 months (1-46 months) after the diagnosis of TGP by biopsy, 17 patients (32%) lost their allografts at a median of 16 months (1-44 months). There was no difference between the 2 groups in terms of any demographic variables, serum creatinine, panel reactive antibody levels, donor-specific antibody frequency, or mean fluorescence intensity values. Patients who lost their allograft had a significantly higher median spot protein to creatinine ratio 2.81 (1.20-6.00) compared to no graft loss patients 1.16 (0.15-2.53), (P < 0.01), and a trends toward a higher mean chronic glomerulopathy (cg) score (1.65 ± 0.93 vs 1.11 ± 0.93) (P = 0.05). There was also no difference in microvascular inflammation or any other Banff injury scores between the 2 groups. Although 117 gene transcripts were upregulated in both groups, 86 and 57 were upregulated in graft loss and functioning allograft groups, respectively. There were significantly increased levels of intragraft endothelial cell-associated transcripts, gene transcripts associated with complement cascade, interleukins and their receptors and granulysin in graft loss patients compared to patients with a functioning allograft.

CONCLUSION

Our results demonstrate differential intragraft gene expression profiles in TGP patients with allograft loss.

The Relationship of the Severity and Category of Acute Rejection With Intimal Arteritis Defined in Banff Classification to Clinical Outcomes

BACKGROUND

It is unclear if the category of acute rejection with intimal arteritis (ARV) is relevant to short- and long-term clinical outcomes and if the graft outcomes are affected by the severity of intimal arteritis.

METHODS

One hundred forty-eight ARV episodes were reviewed and categorized according to the 2013 Banff criteria of AMR: T cell-mediated rejection with intimal arteritis (v) lesion (TCMRV; n = 78), total antibody-mediated rejection with v lesion (AMRV), which were further divided into suspicious AMRV (n = 37) and AMRV (n = 33). The Banff scores of intimal arteritis (v1, v2 and v3) represented low, moderate, and high ARV severity.

RESULTS

The grafts with TCMRV, suspicious AMRV (sAMRV), and AMRV showed similar responses to antirejection therapy, whereas the grafts with v2- or v3-ARV responded significantly poorer compared to those with v1-ARV. The 8-year death-censored graft survival (DCGS) rate was 56.8% of TCMRV versus 34.1% of total AMRV (Log rank, P = 0.03), but the 1- and 5-year DCGS rates were comparable between the 2 groups; moreover, the 1-, 5-, and 8-year DCGS rates of v1-ARV were evidently higher than v2- and v3-ARV (each pairwise comparison to v1-AVR yields P < 0.01); in contrast, the DCGS rates were similar between sAMRV and AMRV. The existing donor-specific antibodies or moderate microvascular inflammation or C4d-positive staining or intensive tubulointerstitial inflammation played a less significant role on the long-term graft survival.

CONCLUSIONS

Compared to the category, the ARV severity is more closely associated with the initial response to antirejection therapy and long-term graft failure. The sAMRV and AMRV might represent a spectrum of the same disorder.

Use of Quantitative Real Time Polymerase Chain Reaction to Assess Gene Transcripts Associated With Antibody-Mediated Rejection of Kidney Transplants

INTRODUCTION

Microarray studies have shown elevated transcript levels of endothelial and natural killer (NK) cell-associated genes during antibody-mediated rejection (AMR) of the renal allograft. This study aimed to assess the use of quantitative real-time polymerase chain reaction as an alternative to microarray analysis on a subset of these elevated genes.

METHODS

Thirty-nine renal transplant biopsies from patients with de novo donor-specific antibodies and eighteen 1-year surveillance biopsies with no histological evidence of rejection were analyzed for expression of 11 genes previously identified as elevated in AMR.

RESULTS

Expression levels of natural killer markers were correlated to microcirculation inflammation and graft outcomes to a greater extent than endothelial markers. Creating a predictive model reduced the number of gene transcripts to be assessed to 2, SH2D1b and MYBL1, resulting in 66.7% sensitivity and 89.7% specificity for graft loss.

DISCUSSION

This work demonstrates that elevated gene expression levels, proposed to be associated with AMR, can be detected by established quantitative real-time polymerase chain reaction technology, making transition to the clinical setting feasible. Transcript analysis provides additional diagnostic information to the classification schema for AMR diagnosis but it remains to be determined whether significant numbers of centres will validate transcript analysis in their laboratories and put such analysis into clinical use.

Immunomodulatory Strategies Directed Toward Tolerance of Vascularized Composite Allografts

BACKGROUND

Achieving tolerance of vascularized composite allografts (VCAs) would improve the risk-to-benefit ratio in patients who undergo this life-enhancing, though not lifesaving, transplant. Kidney cotransplantation along with a short course of high-dose immunosuppression enables tolerance of heart allografts across a full major histocompatibility complex (MHC) mismatch. In this study, we investigated whether tolerance of VCAs across full MHC disparities could be achieved in animals already tolerant of heart and kidney allografts.

METHODS

Miniature swine that were tolerant of heart and/or kidney allografts long term underwent transplantation of myocutaneous VCA across the same MHC barrier. Before VCA transplant, group 1 (n = 3) underwent class I-mismatched kidney transplantation; group 2 (n = 3) underwent 2 sequential class I-mismatched kidney transplantations; group 3 (n = 2) underwent haploidentical MHC-mismatched heart/kidney transplantation; and group 4 (n = 2) underwent full MHC-mismatched heart/kidney transplantation.

RESULTS

All 3 animals in group 1 and 2 of 3 animals in group 2 showed skin rejection within 85 days; 1 animal in group 2 showed prolonged skin survival longer than 200 days. Animals in groups 3 and 4 showed skin rejection within 30 days and regained in vitro evidence of donor responsiveness.

CONCLUSIONS

This is the first preclinical study in which hearts, kidneys, and VCAs have been transplanted into the same recipient. Despite VCA rejection, tolerance of heart and kidney allografts was maintained. These results suggest that regulatory tolerance of skin is possible but not generally achieved by the same level of immunomodulation that is capable of inducing tolerance of heart and kidney allografts. Achieving tolerance of skin may require additional immunomodulatory therapies.

Biomarkers in kidney transplantation: From bench to bedside

Immunosuppressive drug level monitoring and serum creatinine are widely used for kidney transplantation (KT) monitoring. Monitoring of drug level is not the direct measurement of the immune response while the rising of creatinine is too late for detection of allograft injury. Kidney biopsy, the gold standard for KT monitoring, is invasive and may lead to complications. Many biomarkers have been discovered for direct monitoring of the immune system in KT and the benefit of some biomarkers has reached clinical level. In order to use biomarkers for KT monitoring, physicians have to understand the biology including kinetics of each marker. This can guide biomarker selection for specific condition. Herein, we summarize the recent findings of donor specific anti-human leukocyte antigen antibody, B lymphocyte stimulator, interferon-gamma induced protein of 10 kDa, and intracellular adenosine triphosphate monitoring, all of which have very strong evidence support for the clinical use in KT.

Rates and determinants of progression to graft failure in kidney allograft recipients with de novo donor-specific antibody

Understanding rates and determinants of clinical pathologic progression for recipients with de novo donor-specific antibody (dnDSA), especially subclinical dnDSA, may identify surrogate endpoints and inform clinical trial design. A consecutive cohort of 508 renal transplant recipients (n = 64 with dnDSA) was studied. Recipients (n = 388) without dnDSA or dysfunction had an eGFR decline of -0.65 mL/min/1.73 m(2) /year. In recipients with dnDSA, the rate eGFR decline was significantly increased prior to dnDSA onset (-2.89 vs. -0.65 mL/min/1.73 m(2) /year, p < 0.0001) and accelerated post-dnDSA (-3.63 vs. -2.89 mL/min/1.73 m(2) /year, p < 0.0001), suggesting that dnDSA is both a marker and contributor to ongoing alloimmunity. Time to 50% post-dnDSA graft loss was longer in recipients with subclinical versus a clinical dnDSA phenotype (8.3 vs. 3.3 years, p < 0.0001). Analysis of 1091 allograft biopsies found that dnDSA and time independently predicted chronic glomerulopathy (cg), but not interstitial fibrosis and tubular atrophy (IFTA). Early T cell-mediated rejection, nonadherence, and time were multivariate predictors of IFTA. Independent risk factors for post-dnDSA graft survival available prior to, or at the time of, dnDSA detection were delayed graft function, nonadherence, dnDSA mean fluorescence intensity sum score, tubulitis, and cg. Ultimately, dnDSA is part of a continuum of mixed alloimmune-mediated injury, which requires solutions targeting T and B cells.

Blood, urine and faecal metabolite profiles in the study of adult renal disease

Chronic kidney disease (CKD) is a major public health burden and to date traditional biomarkers of renal function (such as serum creatinine and cystatin C) are unable to identify at-risk individuals before the disease process is well under way. To help preventive strategies and maximize the potential for effective interventions, it is important to characterise the molecular changes that take place in the development of renal damage. Metabolomics is a promising tool to identify markers of renal disease since the kidneys are involved in the handling of major biochemical classes of metabolites. These metabolite levels capture a snap-shot of the metabolic profile of the individual, allowing for the potential identification of early biomarkers, and the monitoring of real-time kidney function. In this review, we describe the current status of the identification of blood/urine/faecal metabolic biomarkers in different entities of kidney diseases including: acute kidney injury, chronic kidney disease, renal transplant, diabetic nephropathy and other disorders.

The prognostic significance of glomerular infiltrating leukocytes during acute renal allograft rejection

Transplant glomerulitis, observed in T cell-mediated and antibody-mediated rejection, is histologically characterized by intracapillary mononuclear cell infiltration. However, the prognostic value of counting various glomerular inflammatory cells during rejection has not been elucidated, which is a key step for the introduction of novel biomarkers in the clinics. We immunophenotyped glomerulitis during episodes of acute rejection in order to investigate their predictive value for transplant outcomes. To do so, we included 57 transplant biopsies of 57 renal transplant recipients with biopsy-proven acute rejection with a median follow-up of 4.2 years. We determined average glomerular cell counts for T cells, B cells, Tregs, IL-17(+) cells, neutrophils and macrophages. Logistic and Cox regression models were used to investigate the association of glomerular inflammatory cells with response to therapy and graft failure on a population level. We used novel time-dependent ROC curve analyses to investigate the value of glomerular inflammatory cell infiltrates for the prediction of transplant outcomes, applicable to the individual patient. We identified three cell types that were responsible for glomerulitis during rejection: macrophages, T cells and neutrophils. By quantification of glomerular macrophages, an emerging cell type associated with antibody-mediated rejection, we were able to predict the progression towards death-censored graft failure within the first 500 days after the initial episode of rejection. With the use of novel time-dependent ROC analyses, we propose dynamic sensitivities, specificities, and positive and negative predictive values with their corresponding cut-off values for the average amount of glomerular macrophages, depending on what time after rejection death-censored graft failure needs prediction.

Safe Conversion From Tacrolimus to Belatacept in High Immunologic Risk Kidney Transplant Recipients With Allograft Dysfunction

There is no literature on the use of belatacept for sensitized patients or regrafts in kidney transplantation. We present our initial experience in high immunologic risk kidney transplant recipients who were converted from tacrolimus to belatacept for presumed acute calcineurin inhibitor (CNI) toxicity and/or interstitial fibrosis/tubular atrophy. Six (mean age = 40 years) patients were switched from tacrolimus to belatacept at a median of 4 months posttransplant. Renal function improved significantly from a peak mean estimated glomerular filtration rate (eGFR) of 23.8 ± 12.9 mL/min/1.73 m(2) prior to the switch to an eGFR of 42 ± 12.5 mL/min/1.73 m(2) (p = 0.03) at a mean follow-up of 16.5 months postconversion. No new rejection episodes were diagnosed despite a prior history of rejection in 2/6 (33%) patients. Surveillance biopsies performed in 5/6 patients did not show subclinical rejection. No development of donor-specific antibodies (DSA) was noted. In this preliminary investigation, we report improved kidney function without a concurrent increase in risk of rejection and DSA in six sensitized patients converted from tacrolimus to belatacept. Improvement in renal function was noted even in patients with chronic allograft fibrosis without evidence of acute CNI toxicity. Further studies with protocol biopsies are needed to ensure safety and wider applicability of this approach.

Th-17 Alloimmune Responses in Renal Allograft Biopsies From Recipients of Kidney Transplants Using Extended Criteria Donors During Acute T Cell-Mediated Rejection

Although renal transplantation using expanded criteria donors has become a common practice, immune responses related to immunosenescence in those kidney allografts have not been studied yet in humans. We performed a retrospective molecular analysis of the T cell immune response in 43 kidney biopsies from patients with acute T cell-mediated rejection including 25 from recipients engrafted with a kidney from expanded criteria donor and 18 from recipients grafted with optimal kidney allograft. The clinical, transplant and acute T cell-mediated rejection characteristics of both groups were similar at baseline. The expression of RORγt, Il-17 and T-bet mRNA was significantly higher in the elderly than in the optimal group (p = 0.02, p = 0.036, and p = 0.01, respectively). Foxp3 mRNA levels were significantly higher in elderly patients experiencing successful acute T cell-mediated rejection reversal (p = 0.03). The presence of IL-17 mRNA was strongly associated with nonsuccessful reversal in elderly patients (p = 0.008). Patients with mRNA IL17 expression detection and low mRNA Foxp3 expression experienced significantly more treatment failure (87.5%) than patients with no mRNA IL17 expression and/or high mRNA Foxp3 expression (26.7%; p = 0.017). Our study suggests that the Th17 pathway is involved in pathogenesis and prognosis of acute T cell-mediated rejection in recipients of expanded criteria allograft.