A new histology scoring system for the assessment of the quality of human cartilage repair: ICRS II.

BACKGROUND: A reliable and reproducible method is needed to assess cartilage repair. PURPOSE: This study was undertaken to test the reproducibility of 2 established histological scoring systems, the Modified O'Driscoll Scale (MODS) and International Cartilage Research Society (ICRS) Visual Assessment Scale (ICRS I), and subsequently to develop and evaluate a new grading system for cartilage repair. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: A total of 107 cartilage biopsy specimens were graded using MODS and ICRS I, and the reader variability was measured. The new grading system, ICRS II, was developed and the inter- and intrareader variability determined by 3 independent readers. Collagen type II deposition was assessed immunohistochemically. RESULTS: The MODS and ICRS I demonstrated high interreader variability, with MODS also showing high intrareader variability. A new histological scoring system, ICRS II, was developed comprising 14 criteria to assess parameters related to chondrocyte phenotype and tissue structure. The ICRS II demonstrated lower inter- and intrareader variability compared with MODS or ICRS I. The overall assessment and matrix staining scores had the best correlation coefficients for inter- and intrareader variability (r = .81 and .82, respectively). The extent of collagen type II in cartilage, considered a marker of differentiation toward hyaline cartilage, could represent a measure of good cartilage repair. A correlation coefficient of .56 was obtained between the extent of collagen type II staining and the overall assessment score. CONCLUSION: The ICRS II represents an improvement over current histological cartilage repair grading systems in terms of reader reproducibility. The clinical relevance and its ability to predict long-term repair durability will be assessed once long-term clinical data become available.

Donor age and renal P-glycoprotein expression associate with chronic histological damage in renal allografts.

The contributions of donor kidney quality (partially determined by donor age), allograft rejection, and calcineurin inhibitor nephrotoxicity on the progression of histologic damage of renal allografts are not completely defined. Moreover, the determinants of individual susceptibility to calcineurin inhibitor nephrotoxicity are not known but may include variability in drug transport and metabolism. In a prospective cohort of 252 adult renal allograft recipients treated with a combination of tacrolimus, mycophenolate mofetil, and corticosteroids, we studied 744 renal allograft biopsies obtained regularly from time of transplantation for 3 yr. We assessed determinants of histologic evolution, including tacrolimus exposure, renal P-glycoprotein (ABCB1) expression, and polymorphisms in the CYP3A4, CYP3A5, and ABCB1 genes. Within the first 3 yr after transplantation, we noted a progressive increase in interstitial fibrosis, tubular atrophy, glomerulosclerosis, and vascular intimal thickening. Older donor age, absence of P-glycoprotein expression at the apical membrane of tubular epithelial cells, and combined donor-recipient homozygosity for the C3435T variant in ABCB1 significantly associated with increased susceptibility to chronic allograft damage independent of graft quality at implantation. Changes in graft function over time reflected these associations with donor age and ABCB1 polymorphisms, but it was acute T cell-mediated and antibody-mediated rejection that determined early graft survival. In conclusion, the effects of older donor age reach beyond the quality of the allograft at implantation and continue to be important for histologic evolution in the posttransplantation period. In addition, ABCB1 genotype and expression of P-glycoprotein in renal tubular epithelial cells determine susceptibility to chronic tubulointerstitial damage of transplanted kidneys.

Chronic renal failure: an unexpected presentation.

Chronic renal failure in childhood is mostly caused by a congenital disorder or an acquired form of glomerulonephritis. We describe a case of a 13-year-old boy from Africa who presented with a cerebrovascular accident, malignant hypertension and renal insufficiency. Aetiological workup of his hypertension revealed underlying chronic renal failure due to histologically confirmed haemolytic uraemic syndrome. This case serves to remind clinicians of the serious complications of undiagnosed chronic renal failure in a child.

Upregulation of Igf and Wnt signalling associated genes in pleomorphic adenomas of the salivary glands in PLAG1 transgenic mice.

The Pleomorphic adenoma gene 1 (PLAG1) is involved in various human neoplasias, including pleomorphic adenomas of the salivary glands. Moreover, the oncogenic role of PLAG1 was clearly demonstrated in two independent PLAG1 transgenic mouse founders, in which PLAG1 expression could be targeted to different tissues using the Cre/loxP system. MMTV-Cre-mediated targeted overexpression of PLAG1 in the salivary glands of double transgenic offspring mice, referred to as P1-MCre and P2-MCre mice, induced pleomorphic adenomas in this organ. Igf2, a genuine PLAG1 target gene, was highly upregulated in those tumours as well as in human pleomorphic adenomas of the salivary glands. These and previous observations in other PLAG1-induced tumours e.g. breast adenomyoepitheliomas emphasize the importance of Igf upregulation in such tumours. In this study, further evidence for the role of Igf2 in PLAG1-induced tumourigenesis, is reported. Inactivation of Igf2 in P1-MCre mice leads to a significant delay in tumour development. Since tumour development is not fully abrogated by inactivation of Igf2, other signalling pathways are likely to contribute to PLAG1-induced tumourigenesis as well. Further studies revealed that several genes such as H19, Dlk1, Gtl2, Igfbp2, Igfbp3 and genes involved in Wnt signalling, such as Wnt6, Cyclin D1 and beta-catenin are upregulated in P1-MCre mice in which Igf2 is inactivated. In conclusion, we clearly demonstrate upregulation of several genes associated with Igf and Wnt signalling in PLAG1-induced pleomorphic adenomas. Furthermore, inactivation of Igf2 does not affect upregulation of genes associated with Wnt signalling, which might suggest that both signalling pathways are involved.

MMTV-cre-mediated fur inactivation concomitant with PLAG1 proto-oncogene activation delays salivary gland tumorigenesis in mice.

Proprotein convertases are serine endoproteases implicated in the proteolytic processing of a large variety of regulatory proteins. An important role of proprotein convertases in tumorigenic processes has been suggested by various studies. In this study, the role of the proprotein convertase furin in PLAG1 proto-oncogene-induced salivary gland tumorigenesis was investigated. PLAG1 overexpression in salivary glands has previously been shown to result in salivary gland tumors in 100% of mice within 5 weeks after birth. MMTV-cre-mediated inactivation of fur without over-expression of PLAG1 caused smaller but histologically normal salivary glands. Moreover, the lymph nodes close to the salivary glands were enlarged, and histology showed that they had activated follicles. When genetic ablation of 1 or 2 alleles of fur and overexpression of the PLAG1 transgene were simultaneously achieved, a significant delay in tumorigenesis was observed. Collectively, these results suggest an important role for furin in PLAG1-induced salivary gland tumorigenesis in mice.

Subclinical peritubular capillaritis at 3 months is associated with chronic rejection at 1 year.

BACKGROUND: Peritubular capillaritis has been associated with chronic rejection, but the characteristics of subclinical lesions in peritubular capillaries are unknown. METHODS: Fifty-three renal allograft recipients underwent a protocol biopsy at both 3 and 12 months after transplantation. Subclinical chronic antibody-mediated rejection (CAMR) at 1 year was diagnosed when three or more of five criteria were present: basement membrane multilayering of peritubular capillaries (MLPTC), transplant glomerulopathy, increase in intimal fibrosis between 3 and 12 months, C4d deposition in peritubular capillaries, and the presence of anti-human leukocyte antigen antibodies. RESULTS: Six (11.3%) patients met the criteria of CAMR. MLPTC was the most sensitive (83.3%) and specific (89.1%) histological criterion (P=0.0008). Five patients had peritubular capillaritis at their 3-month biopsy. They all developed MLPTC at 1 year (P<0.0001). Three of the patients with early peritubular capillaritis met the criteria of CAMR at 1 year (P=0.0002). CONCLUSIONS: Through early detection of subclinical peritubular capillaritis, renal allograft recipients who are at risk for development of MLPTC might be identified. Larger series are needed to confirm these preliminary findings, but this report suggests peritubular capillaritis as an early detection marker for patients at risk for CAMR.

Acute rejection in non-compliant renal allograft recipients: a distinct morphology.

Non-compliance for immunosuppressive medication is frequent in renal transplant recipients, and associated with late acute rejection and graft loss. Although numerous studies were published on risk factors and outcome, no data are available on the histopathology of the 'non-compliant' allograft. As non-compliant patients swing between subtherapeutic and toxic doses of immunosuppression, trough levels show large variation. We questioned whether the histology of acute rejection in non-compliers (i) differs from the 'classical' acute rejection; (ii) shows more concomitant calcineurin-inhibitor toxicity; (iii) is associated with C4d and plasma cell (PC)-rich infiltrates. Based on validated interview methods/self reporting, 145 adult renal allograft recipients, transplanted for greater than one yr, on cyclosporine A and corticosteroids, were categorized as either compliant or non-compliant. Non-compliance was defined in 32 patients (22.1%). All late (greater than one yr) allograft biopsies were reviewed (Banff) and immuno-stained for C4d. Computerized morphometry was performed on late biopsies with features of acute cellular rejection. Sixty-two patients had > or =1 late biopsy [41 (36.2%) compliant/21 (65.6%) non-compliant; p = 0.0043], comprising a pool of 90 biopsies (61 compliant/29 non-compliant; p = 0.0303). 'Non-compliant' biopsies had higher scores of C4d (p = 0.0092), acute tubular damage (p = 0.0058), and peritubular capillaritis (p = 0.0070). 'Non-compliant' biopsies with acute cellular rejection showed less interstitial edema (p = 0.0165), more interstitial infiltrate (p = 0.0100), more interstitial fibrosis (p = 0.0277), and more tubular atrophy (p = 0.0197). PC-rich infiltrates correlated with C4d (p = 0.0080). Detection of non-compliance is mandatory as it represents an important cause of graft loss. This study describes histologic features of renal allograft biopsies in non-compliant patients that could help identifying this patient profile.

Duffy and Kidd blood group antigens: minor histocompatibility antigens involved in renal allograft rejection?

BACKGROUND: Minor histocompatibility antigens have been poorly defined. Whether Duffy (FY) and Kidd (JK), polymorphic and immunogenic blood group antigens, widely distributed in human organs, expressed and functional in the kidney, could function as minor histocompatibility antigens and be implicated in renal allograft rejection was questioned. STUDY DESIGN AND METHODS: A retrospective, homogeneous, single-center cohort of 370 renal transplants was analyzed. In all donor/recipient pairs, FY and JK polymorphisms were identified by real-time polymerase chain reaction. In all donor/recipient pairs the matching (m) or mismatching (mm) status was defined for both systems. All biopsies were reviewed, and historical screening results for FY and JK alloantibodies and graft survival were retrospectively analyzed. RESULTS: Although graft survival was not different between the groups, it was observed that FY mm grafts had significantly more chronic lesions compared to FY m grafts. HLA-DR11 was more frequent in both recipients (p = 0.0081) and donors (p = 0.0104) of FY mm couples without chronic allograft nephropathy, suggesting a protective effect for this molecule. JK mm grafts had more interstitial inflammation than JK m grafts (p = 0.0369). CONCLUSION: This renal model unmasks for the first time the role of FY and-to a lesser extent-JK antigens as minor histocompatibility antigens and suggests their potential role for other clinical transplant settings.

Polyomavirus interstitial nephritis and concurrent post-transplant lymphoma in a renal allograft: coincidence or more?

We describe a case of an Epstein-Barr virus (EBV)-negative post-transplant large B-cell non-Hodgkin lymphoma located in the renal allograft, spleen, liver and left inguinal lymph node of a renal recipient and accompanied by a simultaneous polyomavirus-associated nephropathy. To our knowledge, this is the first report of a simultaneous polyomavirus infection and post-transplant lymphoproliferative disorder.

Protein gene product 9.5 and ubiquitin are expressed in metabolically active epithelial cells of normal and pathologic human kidney.

BACKGROUND: In a study initially designed to evaluate the specific protein gene product 9.5 expression in parietal epithelial cells of Bowman's capsule, a marked positivity was also observed in the tubular and collecting duct epithelial cells. Since protein gene product 9.5 is an important enzyme in the ubiquitin system of proteolysis, and plays a regulatory role in cell cycle and proliferation, its presence in specific segments of the nephron was of considerable interest. METHODS: We investigated protein gene product 9.5 and ubiquitin expression in both normal and pathologic renal samples (more than 100 cases) using an immunohistochemical technique. RESULTS: We found that protein gene product 9.5 and ubiquitin were constantly present in Bowman's capsule parietal cells and tubular/collecting duct epithelial cells, with the strongest positivity in metabolically active and proliferative conditions, such as tubular hypertrophy, cellular regeneration and crescent formation. Conversely, the expression of these molecules was attenuated in atrophic tubules. Podocytes were negative. CONCLUSION: The diffuse presence of the protein gene product 9.5 and ubiquitin in normal and pathologic metabolically active epithelial cells of the nephron suggests that these proteins (and likely the whole ubiquitin-proteasome complex) play a fundamental role in the mechanism upregulating protein metabolism of the kidney and that its expression is correlated with activated cellular functions, like proliferation.

Salivary gland tumors in transgenic mice with targeted PLAG1 proto-oncogene overexpression.

Pleomorphic adenoma gene 1 (PLAG1) proto-oncogene overexpression is implicated in various human neoplasias, including salivary gland pleomorphic adenomas. To further assess the oncogenic capacity of PLAG1, two independent PLAG1 transgenic mouse strains were established, PTMS1 and PTMS2, in which activation of PLAG1 overexpression is Cre mediated. Crossbreeding of PTMS1 or PTMS2 mice with MMTV-Cre transgenic mice was done to target PLAG1 overexpression to salivary and mammary glands, in the P1-Mcre/P2-Mcre offspring. With a prevalence of 100% and 6%, respectively, P1-Mcre and P2-Mcre mice developed salivary gland tumors displaying various pleomorphic adenoma features. Moreover, histopathologic analysis of salivary glands of 1-week-old P1-Mcre mice pointed at early tumoral stages in epithelial structures. Malignant characteristics in the salivary gland tumors and frequent lung metastases were found in older tumor-bearing mice. PLAG1 overexpression was shown in all tumors, including early tumoral stages. The tumors revealed an up-regulation of the expression of two distinct, imprinted gene clusters (i.e., Igf2/H19 and Dlk1/Gtl2). With a latency period of about 1 year, 8% of the P2-Mcre mice developed mammary gland tumors displaying similar histopathologic features as the salivary gland tumors. In conclusion, our results establish the strong and apparently direct in vivo tumorigenic capacity of PLAG1 and indicate that the transgenic mice constitute a valuable model for pleomorphic salivary gland tumorigenesis and potentially for other glands as well.

Capillary deposition of complement C4d and C3d in pediatric renal allograft biopsies.

BACKGROUND: Peritubular capillary deposition of C4d (C4d(PTC)) is a marker of antibody-mediated alloresponse and is associated with poor graft survival in adults. C3d(PTC) has received less attention; its significance is unclear. To date no information has been gained in children. METHODS: The prevalence of C4d(PTC) and C3d(PTC) in pediatric renal allograft biopsies (n=77, 31 cadaveric kidneys) was analyzed retrospectively. Associations with histology, donor-specific antibodies (DSAs), and outcome were investigated. RESULTS: The overall prevalence of C4d(PTC) and C3d(PTC) was 52% and 48%, respectively. C3d(PTC) was associated with C4d(PTC) (P<0.0001). Thirty-six percent of acute rejections were cellular, 28% were humoral, and 36% were combined cellular and humoral. C3d(PTC) was found in 57% of acute rejection biopsies. C4d(PTC), but not C3d(PTC), was associated with accumulation of polymorphonuclear cells in peritubular capillaries (P=0.02). Fifty-one percent of late biopsies (>6 months posttransplantation) had features of chronic allograft nephropathy: 50% were C4d(PTC_ positive, and 50% were C3d(PTC) positive. C4d(PTC) positive chronic allograft nephropathy biopsies had more transplant glomerulopathy (P=0.020) and mesangial matrix increase (P=0.026). C3d(PTC) tended to be associated with transplant glomerulopathy (P=0.06), but not with mesangial matrix increase. C4d(PTC) was correlated with DSA (P=0.011). Excluding early nonrejection graft losses, more grafts were lost in the C4d(PTC) positive group (P=0.019). C3d(PTC) was not associated with DSA or graft outcome. CONCLUSIONS: Our results support C4d(PTC) being a hallmark of humoral rejection in pediatric renal transplantation; its presence was associated with DSA and poorer immunologic graft outcome. In contrast, C3d(PTC), although highly associated with C4d(PTC), did not correlate with DSA or outcome.

Regulatory cells, TH1/TH2 unbalance, and antibody-induced chronic rejection in operational tolerance induced by donor-specific blood transfusion.

We developed a rodent model in which donor-specific blood transfusion (DSBT) promotes hyporesponsiveness and graft acceptance. In this model, signs of immune activation are present early posttransplant, with preserved proliferative responses against the donor and a dense cellular infiltrate in tolerant grafts. Intriguingly, an early accumulation of IFN-gamma is seen in grafts destined to become tolerized, supporting recent evidence that Th1 cytokines play a role in tolerance induction. Specific regulatory cells capable of propagating tolerance into naive recipients are operating. These mechanisms of immune activation and the generation of regulatory cells are influenced by immunosuppression (steroids and calcineurin inhibitors). In this model, in a second phase, a Th2 immune deviation occurs and is associated with the development of chronic rejection (vascular obliteration, endothelial IgG deposition, and complement binding). It remains unclear whether chronic rejection in this model is caused by Th2 type regulatory cells or whether chronic rejection is the consequence of an insufficient number of regulatory cells. In the clinic, the current strategy of profoundly inhibiting immune activation (in particular Th1 cytokines/responses) by using high dose calcineurin inhibitors and steroids may prove antagonistic with the development of tolerance, particularly when immunomodulatory strategies (such as DSBT) are applied. Development of chronic rejection in a regulation-based tolerance model suggests that deletion-based tolerogenic strategies may offer a more robust protection against chronic rejection.

Prospective study on late consequences of subclinical non-compliance with immunosuppressive therapy in renal transplant patients.

In this prospective study we compared the incidence of late acute rejections (LAR) and changes in serum-creatinine over time between compliers and noncompliers with immunosuppressive therapy more than 1 year post transplantation and explored the relative contribution of non-compliance and other risk factors in the occurrence of LAR. One hundred and forty-six adult renal transplant recipients were followed during a 5-year period. Patients were interviewed at the beginning of the study and categorized as non-compliers if they admitted to have skipped immunosuppressive medication on a regular basis during the previous 12 months. The occurrence of LAR during the follow-up period was recorded. We identified 22.6% non-compliers of which 21.2% experienced a late acute rejection compared with 8% in the group of compliers at 5 years postinclusion (p < 0.05). Kaplan-Meier survival analysis showed a decreased rejection free time in non-compliers compared with compliers (p = 0.03). Non-compliant patients had a 3.2 higher risk of LAR (Cox regression analysis, p = 0.005). Non-compliers experienced a higher increase in serum-creatinine over time (Linear Mixed Models, p < 0.001). Non-compliance in renal transplant patients more than 1-year post transplantation is associated with an increased risk for LAR and a higher increase in serum-creatinine during the following 5 years.

Mycophenolate mofetil in IgA nephropathy: results of a 3-year prospective placebo-controlled randomized study.

BACKGROUND: Because humoral immunity is believed to play a pivotal role in the pathogenesis of IgA nephropathy (IgAN), a prospective placebo-controlled randomized study was started in patients with IgAN using mycophenolate mofetil (MMF). METHODS: A total of 34 patients with IgAN were treated with salt intake restriction, angiotensin-converting enzyme (ACE) inhibition and MMF 2 g per day (N= 21) or placebo (N= 13). After 36 months of follow-up clinical, biochemical, and radiologic data were analyzed using linear mixed models for longitudinal data and Kaplan-Meier survival analysis. RESULTS: Therapy had to be stopped prematurely in five patients. Two patients (MMF group) evolved to end-stage renal disease (ESRD). There was no difference between groups in the percentage of patients with a decrease of 25% or more in the inulin clearance or with a serum creatinine increase of 50% or more over 3 years. There was also no significant difference between groups in annualized rate of change of serum creatinine, computed by linear regression analysis. No significant difference was noted between groups for inulin clearance, serum creatinine, proteinuria, blood pressure, or other parameters of renal function. Hemoglobin and C-reactive protein were significantly lower in the MMF group compared with the placebo group. As a function of time, a significant decline in both groups was noted of proteinuria, parenchymal thickness of the kidneys and C3d. CONCLUSION: In patients with IgAN at risk for progressive disease, no beneficial effect of 3-year treatment with MMF 2 g per day could be demonstrated on renal function/outcome or proteinuria. However, larger randomized studies are needed to confirm or reject these results.

Microarray screening for target genes of the proto-oncogene PLAG1.

PLAG1 is a proto-oncogene whose ectopic expression can trigger the development of pleomorphic adenomas of the salivary glands and of lipoblastomas. As PLAG1 is a transcription factor, able to activate transcription through the binding to the consensus sequence GRGGC(N)(6-8)GGG, its ectopic expression presumably results in the deregulation of target genes, leading to uncontrolled cell proliferation. The identification of PLAG1 target genes is therefore a crucial step in understanding the molecular mechanisms involved in PLAG1-induced tumorigenesis. To this end, we analysed the changes in gene expression caused by the conditional induction of PLAG1 expression in fetal kidney 293 cell lines. Using oligonucleotide microarray analyses of about 12 000 genes, we consistently identified 47 genes induced and 12 genes repressed by PLAG1. One of the largest classes identified as upregulated PLAG1 targets consists of growth factors such as the insulin-like growth factor II and the cytokine-like factor 1. The in silico search for PLAG1 consensus sequences in the promoter of the upregulated genes reveals that a large proportion of them harbor several copies of the PLAG1-binding motif, suggesting that they represent direct PLAG1 targets. Our approach was complemented by the comparison of the expression profiles of pleomorphic adenomas induced by PLAG1 versus normal salivary glands. Concordance between these two sets of experiments pinpointed 12 genes that were significantly and consistently upregulated in pleomorphic adenomas and in PLAG1-expressing cells, identifying them as putative PLAG1 targets in these tumors.

Regulatory cell-mediated tolerance does not protect against chronic rejection.

BACKGROUND: Regulatory cells prevent graft loss to acute rejection and induce tolerance, possibly by promoting Th2 deviation. Th2 cytokines stimulate B cells, which cause alloantibody-mediated chronic rejection. We searched to determine whether regulatory cell-mediated tolerance protects or not against chronic rejection. METHODS: Heart transplantation (Htx) was performed using RA (RT1P) and PVG (RT1c) rats as donor and recipients. Donor-specific blood transfusion (DSBT) was given on preTx day 12. Secondary grafts were implanted at day 100. Splenocytes were transferred from tolerant rats (and controls) into lightly irradiated (450 rad) naive PVG, which received RA Htx. Primary Htx were investigated for the development of vascular occlusion (VO), the production of Th1/Th2 intragraft cytokines, and for the nature of graft infiltrate as well as for endothelial deposition of immunoglobulin (Ig)G isotypes and complement (C3) binding. Results were compared with rejecting controls (no DSBT) and syngeneic Htx. RESULTS: RA Htx were rejected within 10 days (8, 9, 10x4). PreTx DSBT prolonged primary Htx survival indefinitely (>140 days) with acceptance of secondary donor-specific (but not third-party) grafts (P<0.001). Naive irradiated PVG rats given splenocytes from tolerant rats but not from controls accepted RA Htx, showing the existence of regulatory cells in allograft acceptors. Despite being tolerant, DSBT-treated rats displayed typical features of chronic rejection at day 90 (VO=77%; P<0.001 vs. VO=4% in syngeneic rats). An overt Th2 deviation, particularly intragraft production of interleukin (IL)-4, was observed at day 30. Simultaneously to this Th2 deviation, B cells emerged in the grafts and endothelial deposition of IgG1 (Th2 dependent) and C3 binding were observed. CONCLUSIONS: Regulatory cells that prevent graft loss to acute rejection in primary and secondary grafts do not protect against the development of chronic rejection.

C3D deposition in peritubular capillaries indicates a variant of acute renal allograft rejection characterized by a worse clinical outcome.

BACKGROUND: C4d deposition in peritubular capillaries (PTCs) is a sign of humoral renal allograft rejection and an independent predictor of graft survival. Few investigators have focused on the meaning of capillary C3 deposition in rejecting grafts. Because C3 production can result from both classic and alternative pathway activation of the complement cascade, it is not clear whether C3 deposition indicates a distinct entity of acute rejection (AR) or merely represents a separate form of C4d-positive AR. METHODS: We examined the deposition of C3d in the PTCs of recipients with AR in the first year posttransplantation (n=30). Clinical outcome variables and histology were compared with C3d-negative control patients (n=82). RESULTS: C3d-positive patients demonstrated more frequent preexisting T-cell antibodies (57%) and more re-transplants (37%), and they received more blood transfusions (mean 10.3 units). C3d-positive patients experienced more frequent multiple AR episodes (57%) and delayed graft function (36.7%). All nine C3d-positive recipients screened for posttransplantation donor-specific human leukocyte antigen antibodies demonstrated positive results. Graft failure occurred in 23% of C3d-positive recipients (7.3% in the control group) (P=0.03). C3d-positive biopsies showed significantly less tubulitis (P=0.03), whereas congestive PTCs with intraluminal accumulation of polymorphonuclear leukocytes were conspicuous. Thrombi, fibrinoid necrosis, and acute tubular necrosis were not more pronounced. In 19% of rejection biopsies, C3d deposition in PTCs was present without C4d deposition. In the remaining biopsies, C3d and C4d deposition was found simultaneously. CONCLUSIONS: The deposition of complement factor C3d in PTCs indicates a variant type of AR characterized by a worse clinical outcome.

The effect of FTY 720 on engraftment in a model of spontaneous allograft acceptance.

Further development in organ transplantation requires the utilization of new immunosuppressive drugs that-in addition to being effective against rejection-do not block tolerance. We previously reported that FTY 720, a drug that alters lymphocyte trafficking, has marked anti-rejection properties. We now investigate how FTY 720 influences tolerance in a model of graft acceptance by donor-specific blood transfusion (DSBT). Two different transplant models--heart transplantation (Htx) and intestinal transplantation (Itx)--were studied. We performed orthotopic Itx and heterotopic Htx using fully mismatched inbred male RA (RT1(p)) and PVG (RT1(c)) rats as donors and recipients. Tolerance was induced by DSBT on pre-transplant day -12. To test the effect of FTY 720 on DSBT-induced tolerance, we administered FTY 720 orally prior to DSBT. Itx: control rats succumbed to rejection at 18+/-4 days. DSBT alone prolonged survival to 101.9+/-18 days (P<0.05 vs untreated). Long-term survivors were tolerant (acceptance of secondary donor-specific Htx). Adjunction of FTY 720 prior to DSBT reduced survival to 55.9+/-44.7 days (P<0.05). However, long-term survivors still accepted secondary donor-specific Htx. Htx: control rats survived 9+/-0.6 days. DSBT alone prolonged survival indefinitely (>120 days) and induced tolerance (acceptance of secondary donor-specific Htx). Unlike in Itx, adjunction of FTY 720 prior to DSBT did not reduce Htx survival. Acceptance of secondary donor-specific Htx was not influenced by FTY 720. In Itx, FTY 720 counteracts the beneficial effect of pre-transplant DSBT and triggers acute rejection of primary, but not secondary grafts. In Htx, however, FTY 720 allows full development of tolerance. The mechanisms by which FTY 720 causes rejection in primary intestinal but not in heart grafts need to be elucidated.