Algorithm for total face and multiorgan procurement from a brain-dead donor.

Procurement of a facial vascularized composite allograft (VCA) should allow concurrent procurement of all solid organs and ensure their integrity. Because full facial procurement is time-intensive, "simultaneous-start" procurement could entail VCA ischemia over 12 h. We procured a total face osteomyocutaneous VCA from a brain-dead donor. Bedside tracheostomy and facial mask impression were performed preoperative day 1. Solid organ recovery included heart, lungs, liver, kidneys, and pancreas. Facial dissection time was 12 h over 15 h to diminish ischemia while awaiting recipient preparation. Solid organ recovery began at 13.5 h, during midfacial osteotomies, and concluded immediately after facial explantation. Facial thoracic and abdominal teams worked concurrently. Estimated blood loss was 1300 mL, requiring five units of pRBC and two units FFP. Urine output, MAP, pH and PaO2 remained normal. All organs had good postoperative function. We propose an algorithm that allows "face first, concurrent completion" recovery of a complex facial VCA by planning multiple pathways to expedient recovery of vital organs in the event of clinical instability. Beginning the recipient operation earlier may reduce waiting time due to extensive recipient scarring causing difficult dissection.

Endogenous expansion of regulatory T cells leads to long-term islet graft survival in diabetic NOD mice.

Donor pancreatic lymph node cells (PLNC) protect islet transplants in Non-obese diabetic (NOD) mice. We hypothesized that induced FoxP3(+) regulatory T cells (Tregs) were required for long-term islet engraftment. NOD or NOD.NON mice were treated with ALS (antilymphocyte serum) and transplanted with NOR islets +/-PLNC (5 × 10(7) ). In vivo proliferation and expansion of FoxP3(+) Tregs was monitored in spleen and PLN from ALS- and ALS/PLNC-treated recipient mice. Anti-CD25 depletion was used to determine the necessity of Tregs for tolerance. FoxP3(+) numbers significantly increased in ALS/PLNC-treated recipients compared to ALS-treated mice. In ALS/PLNC-treated mice, recipient-derived Tregs localized to the transplanted islets, and this was associated with intact, insulin-producing ß cells. Proliferation and expansion of FoxP3(+) Tregs was markedly increased in PLNC-treated mice with accepted islet grafts, but not in diabetic mice not receiving PLNC. Deletion of Tregs with anti-CD25 antibodies prevented islet graft tolerance and resulted in rejection. Adoptive transfer of Tregs to secondary NOD.scid recipients inhibited autoimmunity by cotransferred NOD effector T cells. Treg expansion induced by ALS/PLNC-treatment promoted long term islet graft survival. Strategies leading to Treg proliferation and localization to the transplant site represent a therapeutic approach to controlling recurrent autoimmunity.

Vascularized bone marrow-based immunosuppression inhibits rejection of vascularized composite allografts in nonhuman primates.

Vascularized composite allograft (VCA) transplantation (also referred to as composite tissue allotransplantation) has demonstrated clinical success in cases of hand, arm and face transplantation despite prior belief that skin provides an insurmountable barrier to allograft rejection. These overall good outcomes are facilitated by substantial immunosuppressive requirements in otherwise healthy patients, yet still demonstrate frequent rejection episodes. We developed a nonhuman primate model of facial segment allotransplantation to elucidate the unique pathophysiology and immunosuppressive requirements of VCA with addition of concomitant vascularized bone marrow (VBM). Heterotopically transplanted facial segment VCA with VBM treated only with tacrolimus and mycophenolate mofetil (MMF) demonstrated prolonged rejection-free survival, compared to VCA without VBM that demonstrated early rejection episodes and graft loss. While VCA with VBM demonstrated sporadic macrochimerism, acute and chronic rejection and graft loss occurred after discontinuation of immunosuppression. These data support an immunomodulatory role of VBM in VCA that reduces immunosuppressive requirements while providing improved outcomes.

Guidelines for the diagnosis of antibody-mediated rejection in pancreas allografts-updated Banff grading schema.

The first Banff proposal for the diagnosis of pancreas rejection (Am J Transplant 2008; 8: 237) dealt primarily with the diagnosis of acute T-cell-mediated rejection (ACMR), while only tentatively addressing issues pertaining to antibody-mediated rejection (AMR). This document presents comprehensive guidelines for the diagnosis of AMR, first proposed at the 10th Banff Conference on Allograft Pathology and refined by a broad-based multidisciplinary panel. Pancreatic AMR is best identified by a combination of serological and immunohistopathological findings consisting of (i) identification of circulating donor-specific antibodies, and histopathological data including (ii) morphological evidence of microvascular tissue injury and (iii) C4d staining in interacinar capillaries. Acute AMR is diagnosed conclusively if these three elements are present, whereas a diagnosis of suspicious for AMR is rendered if only two elements are identified. The identification of only one diagnostic element is not sufficient for the diagnosis of AMR but should prompt heightened clinical vigilance. AMR and ACMR may coexist, and should be recognized and graded independently. This proposal is based on our current knowledge of the pathogenesis of pancreas rejection and currently available tools for diagnosis. A systematized clinicopathological approach to AMR is essential for the development and assessment of much needed therapeutic interventions.

Influence of culturing on the survival of major histocompatibility complex-compatible and -incompatible thyroid grafts in rats.

Culturing Fischer thyroid fragments promotes their survival in major histocompatibility complex (MHC) -incompatible ACI rats but not in MHC- compatible Lewis animals.

The detrimental effect of poor early graft function after laparoscopic live donor nephrectomy on graft outcomes.

We undertook this study to assess the rate of poor early graft function (EGF) after laparoscopic live donor nephrectomy (lapNx) and to determine whether poor EGF is associated with diminished long-term graft survival. The study population consisted of 946 consecutive lapNx donors/recipient pairs at our center. Poor EGF was defined as receiving hemodialysis on postoperative day (POD) 1 through POD 7 (delayed graft function [DGF]) or serum creatinine >/= 3.0 mg/dL at POD 5 without need for hemodialysis (slow graft function [SGF]). The incidence of poor EGF was 16.3% (DGF 5.8%, SGF 10.5%), and it was stable in chronologic tertiles. Poor EGF was independently associated with worse death-censored graft survival (adjusted hazard ratio (HR) 2.15, 95% confidence interval (CI) 1.34-3.47, p = 0.001), worse overall graft survival (HR 1.62, 95% CI 1.10-2.37, p = 0.014), worse acute rejection-free survival (HR 2.75, 95% CI 1.92-3.94, p < 0.001) and worse 1-year renal function (p = 0.002). Even SGF independently predicted worse renal allograft survival (HR 2.54, 95% CI 1.44-4.44, p = 0.001). Risk factors for poor DGF included advanced donor age, high recipient BMI, sirolimus use and prolonged warm ischemia time. In conclusion, poor EGF following lapNx has a deleterious effect on long-term graft function and survival.

The Maryland aggregate pathology index: a deceased donor kidney biopsy scoring system for predicting graft failure.

Despite the common use of diagnostic pretransplant deceased donor kidney biopsy, there is no consensus on the prognostic significance of the pathologic findings. In order to assist clinicians with interpretation we analyzed 371 pretransplant biopsies and correlated the findings with graft failure. Glomerular pathology was assessed with percent glomerulosclerosis (GS), glomerular size and periglomerular fibrosis (PGF); vascular pathology with arterial wall-to-lumen ratio (WLR) and arteriolar hyalinosis and interstitial pathology with measurement of cumulative fibrosis and presence of scar. Using two-thirds of the study population as a model-development cohort, we found that biopsy features independently associated with an increased risk of graft failure were GS > or =15%, interlobular arterial WLR > or =0.5 and the presence of PGF, arteriolar hyalinosis or scar. The Maryland Aggregate Pathology Index (MAPI), was developed from these parameters and validated on the remaining one-third of the population. Five-year actuarial graft survival was 90% for kidneys with MAPI scores between 0 and 7, 63% for scores from 8 to 11 and 53% for scores from 12 to 15 (p < 0.001). We conclude MAPI may help transplant physicians estimate graft survival from the preimplantation biopsy findings, in clinical situations similar to this study population (cold ischemia over 24 h, GS < 25%).

HIV-infected liver and kidney transplant recipients: 1- and 3-year outcomes.

Improvements in human immunodeficiency virus (HIV)-associated mortality make it difficult to deny transplantation based upon futility. Outcomes in the current management era are unknown. This is a prospective series of liver or kidney transplant recipients with stable HIV disease. Eleven liver and 18 kidney transplant recipients were followed for a median of 3.4 years (IQR [interquartile range] 2.9-4.9). One- and 3-year liver recipients' survival was 91% and 64%, respectively; kidney recipients' survival was 94%. One- and 3-year liver graft survival was 82% and 64%, respectively; kidney graft survival was 83%. Kidney patient and graft survival were similar to the general transplant population, while liver survival was similar to the older population, based on 1999-2004 transplants in the national database. CD4+ T-cell counts and HIV RNA levels were stable; and there were two opportunistic infections (OI). The 1- and 3-year cumulative incidence (95% confidence intervals [CI]) of rejection episodes for kidney recipients was 52% (28-75%) and 70% (48-92%), respectively. Two-thirds of hepatitis C virus (HCV)-infected patients, but no patient with hepatitis B virus (HBV) infection, recurred. Good transplant and HIV-related outcomes among kidney transplant recipients, and reasonable outcomes among liver recipients suggest that transplantation is an option for selected HIV-infected patients cared for at centers with adequate expertise.

Banff schema for grading pancreas allograft rejection: working proposal by a multi-disciplinary international consensus panel.

Accurate diagnosis and grading of rejection and other pathological processes are of paramount importance to guide therapeutic interventions in patients with pancreas allograft dysfunction. A multi-disciplinary panel of pathologists, surgeons and nephrologists was convened for the purpose of developing a consensus document delineating the histopathological features for diagnosis and grading of rejection in pancreas transplant biopsies. Based on the available published data and the collective experience, criteria for the diagnosis of acute cell-mediated allograft rejection (ACMR) were established. Three severity grades (I/mild, II/moderate and III/severe) were defined based on lesions known to be more or less responsive to treatment and associated with better- or worse-graft outcomes, respectively. The features of chronic rejection/graft sclerosis were reassessed, and three histological stages were established. Tentative criteria for the diagnosis of antibody-mediated rejection were also characterized, in anticipation of future studies that ought to provide more information on this process. Criteria for needle core biopsy adequacy and guidelines for pathology reporting were also defined. The availability of a simple, reproducible, clinically relevant and internationally accepted schema for grading rejection should improve the level of diagnostic accuracy and facilitate communication between all parties involved in the care of pancreas transplant recipients.

Molecular Adsorbent Recirculating System Support Followed by Liver Transplantation for Multiorgan Failure From Heatstroke.

BACKGROUND: Exertional heatstroke is an extremely rare cause of fulminant hepatic failure. Maximal supportive care has failed to provide adequate survival in earlier studies. This is particularly true in cases accompanied by multiorgan failure. METHODS AND MATERIALS: Our prospectively collected transplant database was retrospectively reviewed to identify patients undergoing liver transplantation for heatstroke between January 1, 2012, and December 31, 2016. We report 3 consecutive cases of male patients with fulminant hepatic failure from exertional heatstroke. RESULTS: All patients developed multiorgan failure and required intubation, vasopressor support, and renal replacement therapy. All patients were listed urgently for liver transplantation and were supported with the molecular adsorbent recirculating system while awaiting transplantation. All patients underwent liver transplantation alone and are alive and well, with recovered renal function, normal liver allograft function, and no chronic sequelae of their multiorgan failure at more than one year. CONCLUSION: Extreme heatstroke leading to whole-body organ dysfunction and fulminant liver failure is a complex entity that may benefit from therapy using the Molecular Adsorbent Recirculating System while waiting for liver transplantation as a component of a multidisciplinary, multiorgan system approach.

Synthesis-secretion coupling of insulin. Effect of cyclosporin.

This study investigated the effects of cyclosporin (Cs) on insulin secretion and synthesis from the endocrine pancreas. With in vitro perfused pancreases from control and Cs-treated rats (1, 5, 10, or 25 mg.kg-1.day-1 for 2 wk), a dose-response relationship between Cs dose and inhibition of insulin secretion was demonstrated. Examination of the dynamic secretory response to a glucose stimulus (200 mg/dl) over a 3-h perfusion revealed an inhibition of all three secretory phases. Similarly, the ability of the pancreases to synthesize insulin decreased as a function of Cs dose. Reversibility of Cs toxicity on the pancreas was established by 2 wk after cessation of treatment. To evaluate the effect of Cs treatment in vivo, intravenous glucose tolerance tests were performed. Rats treated with 25 mg.kg-1.day-1 Cs for 2 wk had significantly lower k values (slope of log glucose concentration over time) than controls. At 10 mg.kg-1.day-1, although curves that appeared abnormal were observed, k values were not significantly different from those of controls. In summary, this study demonstrates the profound inhibitory effect of Cs on the endocrine pancreas.

A neural network model for predicting pancreas transplant graft outcome.

OBJECTIVE: To compare the results of a neural network versus a logistic regression model for predicting early (0-3 months) pancreas transplant graft survival or loss. RESEARCH DESIGN AND METHODS: This study was a cross-sectional, secondary analysis of demographic and clinical data from 117 simultaneous pancreas-kidney (SPK), 35 pancreas-after-kidney (PAK), and 8 pancreas-transplant-alone (PTA) patients (n = 160). The majority of patients were men (57%) and were white (90.1%), with a mean age of 39 +/- 8.09 years. Of the patients, 23 (14.4%) experienced early graft loss, which included any loss owing to technical or immunological causes, and death with a functional graft. Data were analyzed with a logistic regression model for multivariate analysis and a backpropagation neural network (BPNN) model. RESULTS: A total of 12 predictor variables were chosen from literature and transplant surgeon recommendations. A logistic model with all predictor variables included correctly classified 93.53% of cases. Model sensitivity was 35.71%; specificity was 100% (pseudo-R2 0.24). Of the predictors, history of alcohol abuse (odds ratio [OR] 32.39; 95% CI 1.67-626.89), having a PAK or PTA (OR 13.6; 95% CI 2.20-84.01), and use of a nonlocal organ procurement center (OPO) (OR 4.51; 95% CI 0.78-25.96) were most closely associated with early graft loss. The BPNN model with the same 12 predictor variables correctly predicted 92.50% of cases (R2 0.71). Model sensitivity was 68%; specificity was 96%. Of the predictors, the three variables most closely associated with graft outcome in this model were recipient/donor weight difference >50 lb, having a PAK or PTA, and use of a nonlocal OPO. CONCLUSIONS: First, the BPNN model correctly predicted 92.5% of graft outcomes versus the logistic model (93.53%). Second, the BPNN model rendered more accurate predictions (>0.70 = loss; <0.30 = survival) versus the logistic model (>0.50 = loss; <0.50 = survival). Third, the BPNN model was more sensitive (68%) than the logistic model (35.71%) to graft failures and demonstrated an almost threefold increase in explained variance (R2 = 0.71 vs. 0.24). These results suggest that the BPNN model is a more powerful tool for predicting early pancreas graft loss than traditional multivariate statistical models.

The effect of methimazole, iodine and splenocytes on thyroid transplants in BB/Wor rats.

BACKGROUND: BB/Wor rats develop spontaneous autoimmune insulin-requiring diabetes mellitus and lymphocytic thyroiditis (LT). Our investigations examined the effect of the thyroid-specific agents, iodine and methimazole (MMI) on thyroid graft survival in BB/Wor rats, compared the intrathyroidal cytokine mRNA expression of endogenous and engrafted thyroids, and ascertained whether unfractionated splenocytes could protect thyroid grafts from lymphocytic infiltration. METHODS: In study 1, 0.025% iodine water-treated LT-prone NB line BB/Wor rats were randomized to receive one of the following treatments: (1) 1.0 x 10(8) splenocytes, IV from LT-resistant WA line BB/Wor rats, (2) WA rat thyroid transplants, (3) both, or (4) neither (controls). In study 2, after thyroid transplantation, LT-prone BB/Wor rats were randomized to receive (1) WA splenocytes, (2) 0.025% iodine water, (3) 0.05% MMI water or, (4) tap water (controls). The incidence of LT was determined by microscopic inspection after hematoxylin and eosin staining. Lymphocytic infiltrates were characterized by immunohistochemistry. Cytokine mRNA was detected by RT-PCR. RESULTS: Grafts from MMI-treated rats had a significantly lower incidence of lymphocytic infiltration (MMI: 2/5; Tap: 5/5; I 5/5, P<0.05, chi2). IL-10 mRNA was expressed in 77% (7/9) endogenous thyroids and 20% (1/5) of the transplanted WA thyroids (P<0.05, chi2) from iodine-treated rats with LT. There was no difference in IL-12 mRNA expression. Lymphocytic infiltration occurred in 100% of the splenocyte-treated graft recipients. Both endogenous and engrafted thyroids contained CD4 and C8 T cells with scattered IgG staining. CONCLUSION: Target organ-specific interventions that suppress antigen presentation may have an adjunctive role in transplantation tolerance. The differential expression of IL-10 may indicate preferential Th2 lymphocyte activation in the endogenous tissues.

Evidence that cyclosporine prevents rejection and recurrent diabetes in pancreatic transplants in the BB rat.

Cyclosporine prevents the development of diabetes in spontaneously diabetic BB rats and NOD mice. However, islet transplants have been shown to be subject to immunologic destruction in hosts treated with CsA and anti-CD4 antibody or those rendered tolerant to donor antigens. This study determines whether the minimum dose of CsA necessary to prevent rejection of pancreatic transplants will also prevent recurrent diabetes in pancreas transplants in BB rats. Lewis recipients promptly reject BN (n = 13, MST 9.2 +/- 0.7 days) and Fisher (n = 6, MST = 11.3 +/- 0.8 days) pancreatic transplants. Treatment with CsA 5 mg/kg/day 0-50 days posttransplant and 2 mg/kg/day 51-100 days (low-dose CsA) produced indefinite survival of BN (n = 5) but not Fisher (n = 4) allografts. Fisher allografts were uniformly successful if maintained on 5 mg/kg/day (n = 4). Treatment with CsA 5 mg/kg/day for 14 days had no deleterious effect on glucose tolerance in Lewis isografts (control [K = 1.81 +/- 0.24, n = 8] vs. CsA treated [K = 1.76 +/- 0.20, n = 8, P = NS]). Low-dose CsA ensured permanent survival of MHC-compatible WF (n = 7, MST greater than 115 days) and MHC-incompatible BN (n = 9, MST greater than 117 days, P = NS) pancreatic transplants in spontaneously diabetic BB/Wor hosts. Three of 11 recipients surviving greater than 100 days enjoyed seemingly permanent acceptance of their allografts after discontinuation of CsA. Immunocompetence was demonstrated by rejection of their pancreas transplants when challenged with donor skin. Vascularized pancreatic allografts treated with CsA appear to be less vulnerable to recurrent diabetes than are islet transplants. Low-dose CsA protects vascularized pancreatic allografts in BB rats from both rejection and recurrent diabetes.

Influence of culturing on the functioning of major-histocompatibility-complex-compatible and incompatible islet grafts in diabetic mice.

Culturing B10.BR (H-2k) islets promotes their survival in major histocompatibility complex (MHC)-incompatible BALB/c (H-2d) mice, but not in MHC-compatible CBA (H-2k) animals. These results provide further evidence that MHC restriction is involved in transplantation immunity--i.e., that allografts are only recognized as foreign if they possess donor macrophages (or cells of this family), or if antigen-presenting cells MHC-compatible with the graft can be provided by the host.

Dominance of tissue-restricted cytotoxic T lymphocytes in the response to allogeneic renal epithelial cell lines.

Our current knowledge of cytotoxic T lymphocytes (CTL) is largely derived from studies of effector populations generated in allogeneic mixed leukocyte cultures (MLC) and assayed for lytic activity to lymphoid cell (LC) targets. We herein report that the CTL response to allogeneic renal epithelial cell lines (REC) is dominated by effectors that efficiently lyse REC targets but show little cross-reactivity with LC targets. In contrast, CTL generated against allogeneic spleen cell stimulators (ie., in MLC) lysed REC and LC targets at comparable levels. Lytic activity in both types of cultures was mediated by CD8+TCRalpha/beta+ cells directed to classical H2 class I alloantigens. Anti-REC effectors cross-reacted with fibroblast and macrophage targets but not with targets commonly used to detect alloreactive CTL, such as lipopolysaccharide- or Con A-stimulated lymphoblasts or lymphoid tumor lines, whereas MLC-elicited effectors efficiently lysed all targets. CTL clones propagated from anti-REC cultures exhibited the same allospecificity and tissue specificity as bulk anti-REC effectors. Individual CTL clones were highly heterogeneous in their capacity to recognize the same class I alloantigen expressed on cells derived from different tissues. These data demonstrate that the cellular environment in which CD8 precursors encounter class I alloantigens can have a profound effect on the cell-type specificity of CTL populations. An important implication of these data is that conventional assays of CTL lytic activity may fail to reveal a significant component of the host response to allogeneic tissues.

Inhibition by cyclosporine of insulin secretion--a beta cell-specific alteration of islet tissue function.

We have reported the potent inhibitory effect of cyclosporine on glucose-induced insulin release in in vitro perfused pancreases. Suppression of both phases of release indicates inhibition of secretion and synthesis. Further studies were performed to examine the effect of high extracellular Ca2+ (4.875 mM). High Ca2+ failed to potentiate release in CsA-treated pancreases, thus we are focusing on the integrity of Ca(2+)-dependent signals in the beta cell. In this study, four groups of pancreases were perfused at 16.7 mM glucose: Control +/- somatostatin (SRIF) and CsA-treated +/- SRIF (60 nM). In control rats, the total 2-hr release decreased 40% with SRIF, from 42.7 +/- 5.5 to 25.5 +/- 3.9 micrograms/300 g body weight (P less than .05). In CsA-treated rats, release decreased 55% with SRIF, from 8.9 +/- 1.1 to 4.0 +/- 0.6 micrograms/300 g body weight. Further, at every time point of these CsA-treated rats, there was approximately 15% greater inhibition by SRIF than in controls. Pancreatic insulin contents were determined, indicating marked depletion of insulin stores in CsA-treated rats (190 +/- 9 vs. 76 +/- 5 micrograms/300 g body weight, P less than .01). Arginine-stimulated secretion of insulin and glucagon was also examined in control and CsA-treated pancreases. CsA exerted no effect on arginine-stimulated glucagon release, yet inhibited insulin approximately 50%. From these studies, we conclude that normal SRIF inhibitory mechanisms must be at least partially intact in CsA-treated pancreases during glucose-induced insulin release, and that CsA inhibition is specific for insulin release, as glucagon stores and arginine-stimulated glucagon release are unaffected by CsA.

Simultaneous pancreas/kidney transplantation--a comparison of enteric and bladder drainage of exocrine pancreatic secretions.

Simultaneous pancreas/kidney transplantation (SPK) has evolved to become a therapeutic option for patients with renal failure resulting from type 1 diabetes mellitus. However, the appropriate route for drainage of the exocrine secretions of the pancreas allograft remains unclear. While bladder drainage (BD) is the current state of the art, it is associated with a high frequency of urologic complications, including urinary tract infections, hematuria, metabolic acidosis, dehydration, and reflux pancreatitis. Although enteric drainage (ED) is the more physiologic route, it has been associated in the past with decreased graft survival and increased infectious complications. In addition, BD offered a technique for detection of rejection through measurement of urinary amylase. However, with the advent of improved immunosuppression and antibiotic therapy, percutaneous pancreas biopsy, improved radiologic imaging, and greater understanding of pancreas transplantation, we hypothesized that ED could be performed without increased morbidity or cost. A group of 23 consecutive SPK was performed with ED during the period from July 1995 to November 1995. Another 23 age- and sex-matched recipients of SPK with BD performed from November 1994 to June 1995 served as a historical control group. Because of the differing lengths of follow-up, data were analyzed with respect to the first six months posttransplant. ED and BD were associated with equivalent actuarial one-year patient and graft survival rates: 100% and 88% for ED, and 96% and 91% for BD, respectively. Hospital charges, length of stay, readmissions, rejection, sepsis-related procedures were also equivalent in ED and BD. However, ED was associated with significantly fewer urinary tract infections and urologic complications. In addition, no grafts were lost as the result of sepsis. In the setting of SPK, ED represents a viable alternative to BD for primary drainage of pancreas exocrine secretions. Further studies with extended lengths of follow-up are necessary to confirm our observations.

CD103+ CTL accumulate within the graft epithelium during clinical renal allograft rejection.

BACKGROUND: We have previously reported that activated CD8+TCRalphabeta+ cells that express high levels of the beta7 integrin CD103 (formerly alphaE, MLA) are present at the graft site during clinical renal allograft rejection. This observation potentially provides new insight into the mechanisms underlying renal allograft destruction because the ligand of CD103 is the epithelial cell-specific molecule E-cadherin, which is known to be expressed by critical graft functional elements such as the renal tubular epithelium. We herein used combined fluorescence-activated cell sorter (FACS) and immunohistochemical (IHC) analyses of transplant nephrectomy (TN) specimens to demonstrate that CD103+ cytolytic T lymphocytes (CTLs) specifically home to the graft epithelium during rejection episodes. METHODS: Serial sections of TN specimens undergoing histologically confirmed cellular rejection (n=7) were stained with anti-CD8 or anti-CD103 and were scored for the presence of positively stained cells within the tubular basement membrane. Freshly isolated graft-infiltrating lymphocytes were subjected to three-color FACS analyses to define the extended phenotypic characteristics of CD103+ cells detected by IHC. RESULTS: CD103+ cells in all specimens were biased towards an intratubular localization. On average, the percentage of CD103+ cells with an intraepithelial localization was 52.2+/-13.1 compared to 12.0+/-3.5 for pan CD8+ cells (mean+/-SE, n=5). FACS analyses confirmed that CD103+ cells detected by IHC exhibited the salient characteristics of CD8+ CTLs (large CD8+TCRalphabeta+CD62L-CD11a(hi)perforin+). The CD103- subset of graft-infiltrating CD8 cells also exhibited a CTL phenotype, but these were predominantly restricted to the graft interstitium. CONCLUSIONS: These data implicate CD103 as a homing receptor that targets graft-infiltrating CD8+ CTLs to the graft epithelium. Given the strong association of tubulitis with clinical rejection, these data are consistent with a role for the CD103+ CTL subset as an effector mechanism in renal allograft destruction.