Peritubular capillary C4d deposition and renal outcome in post-transplant IgA nephropathy

BACKGROUNDS: Immunological staining of the transplanted kidney for C4d in peritubular capillaries (C4d(PTC)) has emerged as a useful method to detect antibody-mediated rejection in situ. In this retrospective study, we evaluated the prevalence of C4d(PTC) deposition in allograft renal biopsies diagnosed of IgA nephropathy (IgAN) and analysed its clinical significance. METHOD: Sixty-six biopsy specimens of post-transplant IgAN, which were obtained to evaluate azotemia and/or heavy proteinuria, were examined by immunohistochemical staining of the paraffin sections with polyclonal antibody for C4d. RESULTS: C4d was stained positively in peritubular capillaries in 16 (24%) of the 66 cases. The C4d(PTC)-negative (n=50) and C4d(PTC)-positive groups (n=16) were not different in recipient gender, age, donor age, type of donor (living vs. cadaveric), interval from transplantation to graft biopsy (41.6+/- 21.8 vs. 48.3+/-26.1 months) and post-biopsy follow-up period (60.3+/-23.3 vs. 56.9+/-25.4 months). During the follow-up period, 12 of 50 (24%) although the incidence of graft failure was not different by the C4d deposition in peritubular capillaries, intervals from renal biopsy to graft failure tended to be shorter in C4d(PTC)-positive cases than C4d(PTC)-negative cases. In Kaplan-Meier analysis, the renal allograft function of the C4d(PTC)-positive group deteriorated more rapidly than that of the C4d(PTC)-negative group (p<0.05). Histologically, the C4d(PTC)-positive group had findings suggestive of acute cellular rejection more commonly than the C4d(PTC)-negative group (p<0.01). CONCLUSIONS: Evidence of humoral rejection, as demonstrated by C4d(PTC) deposition, was concurrently present in significant portions of post-transplant IgAN biopsy specimens and was associated with more rapid deterioration of renal function. These results suggest that C4d(PTC) positivity needs to be determined at the time of biopsy even in cases of post-transplant glomerulonephritis and immunosuppression may need to be modified accordingly.     

Successful rescue of late-onset acute T-cell mediated rejection with anti-CD25 antibody: a case report

Abstract:  A 56-yr-old Japanese male with a history of diabetic nephropathy underwent a HLA 5/6 mismatch and ABO-compatible living-related kidney transplantation (donor: his 49-yr-old wife). A pre-transplant standard NIH complement-dependent cytotoxicity cross-match (Xm) test, a flow-cytometric T-cell Xm, and a FlowPRA™ test were totally negative. Inductionimmunosuppressive protocol consisted of tacrolimus, mycophenolate mofetil, methylprednisolone, and basiliximab (BAS). The patient's post-operative course was almost uneventful, and the graft was functioning well (sCr 1.1 mg/dL). He developed general fatigue, and his sCr was elevated to 2.2 mg/dL 792 d after transplant. A graft biopsy showed acute T-cell mediated rejection Banff grade IB (i3, t3, g0, v0, ptc0, C4d staining negative). The conventional anti-rejection therapy could not improve his graft function; therefore, we added BAS to eliminate activated graft-infiltrating T-cells. He responded to the rescue therapy, and the improvement in graft function was confirmed by a subsequent graft biopsy. He enjoyed his health without any opportunistic infections.     

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

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

The fate of C4d positive kidney allografts lacking histological signs of acute rejection

BACKGROUND: C4d deposits in renal transplants are known to be an independent risk factor of graft failure. The current analysis evaluates the impact of C4d deposits on graft function and survival in renal transplants without morphological signs of rejection. METHODS: We retrospectively analyzed diagnostic transplant biopsies performed due to allograft dysfunction from June 1994 to June 2001 at the University Hospital in Basel. STUDY GROUP: Grafts/patients with focal or diffuse positivity of C4d along peritubular capillaries; absence of morphological signs of acute cellular and/or humoral rejection; up to 3 year follow-up analysis post index biopsy. Patients treated with anti-rejection therapy or an increase in maintenance immunosuppression post biopsy (intervention group = IG) were compared to patients with unaltered immunosuppression (standard group = SG). RESULTS: Study group: 22 biopsies/patients out of 400 biopsies (5%) were included into the study, 17 in the SG and 5 in the IG. Patient survival (1-/3-years): SG: 100/94%, IG: 80/80%; graft survival censored for death (1-/3-years): SG: 82.5/68.8%, IG: 100/100%; serum creatinine (micromol/l) at index biopsy/1-year/3-years: SG: 221 +/- 70/231 +/- 103/245 +/- 124, IG: 217 +/- 100/143 +/- 28/177 +/- 55; acute rejection episodes within 1 year post index biopsy: SG: 4 (4 patients), IG: 1 (1 patient); all differences not significant. Lowest serum creatinine within 4 weeks post index biopsy (IG vs. SG): 108 +/- 25 vs. 181 +/- 61, p = 0.02. CONCLUSIONS: C4d positivity in kidney transplants lacking histological evidence of acute rejection is not associated with rapid functional graft deterioration, even in untreated cases. However, anti-rejection therapy results in the improvement of kidney function. Thus, even in grafts with normal histology, the detection of C4d in diagnostic biopsies can be interpreted as a sign of "smoldering" rejection that benefits from therapy.     

Improved suppression of circulating complement does not block acute vascular rejection of pig-to-rhesus monkey cardiac transplants

At present, acute vascular rejection (AVR) remains a primary obstacle inhibiting long-term graft survival in the pig-to-non-human primate transplant model. The present study was undertaken to determine whether repetitive injection of low dose Yunnan-cobra venom factor (Y-CVF), a potent complement inhibitor derived from the venom of Naja kaouthia can completely abrogate hemolytic complement activity and subsequently improve the results in a pig-to-rhesus monkey heterotopic heart transplant model. Nine adult rhesus monkeys received a heterotopic heart transplant from wild-type pigs and the recipients were allocated into two groups: group 1 (n = 4) received repetitive injection of low dose Y-CVF until the end of the study and group 2 (n = 5) did not receive Y-CVF. All recipients were treated with cyclosporine A (CsA), cyclophosphamide (CyP) and steroids. Repetitive Y-CVF treatment led to very dramatic fall in CH50 and serum C3 levels (CH50 < 3 units/C3 remained undetectable throughout the experiment) and successfully prevented hyperacute rejection (HAR), while three of five animals in group 2 underwent HAR. However, the continuous suppression of circulating complement did not prevent AVR and the grafts in group 1 survived from 8 to 13 days. Despite undetectable C3 in circulating blood, C3 deposition was present in these grafts. The venular thrombosis was the predominant histopathologic feature of AVR. We conclude that repetitive injection of low dose Y-CVF can be used to continuously suppress circulating complement in a very potent manner and successfully prevent HAR. However, this therapy did not inhibit complement deposition in the graft and failed to prevent AVR. These data suggest that using alternative pig donors [i.e. human decay accelerating factor (hDAF)-transgenic] in combination with the systemic use of complement inhibitors may be necessary to further control complement activation and improve survival in pig-to-non-human primate xenotransplant model.     

Complement inhibition with an anti-C5 monoclonal antibody prevents hyperacute rejection in a xenograft heart transplantation model

BACKGROUND: The present study was undertaken to determine whether anti-complement 5 (C5) monoclonal antibodies (mAb) prevent hyperacute rejection (HAR) in a rat-to-presensitized mouse heart transplantation model and whether these mAb, combined with cyclosporine (CsA) and cyclophosphamide (CyP), can achieve long-term graft survival. METHODS: BALB/c mice were presensitized with 2x10(7) splenocytes from Lewis rats 14 days before grafting. Heart grafts from Lewis rats were heterotopically transplanted into BALB/c mice. Presensitized mice were treated with either anti-C5 mAb or a combination of anti-C5 mAb, CsA, and CyP. Controls included: presensitized mice with no treatment, presensitized mice treated with either CsA + CyP or IgG, and nonpresensitized mice with either no treatment or with CsA + CyP treatment. RESULTS: Although typical features of HAR were evident in the presensitized grafts, the mAb completely inhibited complement activation and successfully prevented HAR. Despite complement inactivation, the graft was rejected on postoperative day 6 with acute vascular rejection (AVR) also known as delayed xenograft rejection (DXR). Notably, this type of rejection cannot be effectively overcome by CsA and CyP. CONCLUSIONS: We conclude that (1) anti-C5 mAb prevents HAR, (2) AVR/DXR still occurs when HAR is prevented by complement inactivation, and (3) AVR/DXR cannot be overcome by conventional immunosuppression. These data suggest that anti-C5 mAb may be valuable for preventing HAR in future clinical xenotransplantation and that additional interventions may be required to address AVR/DXR.     

Selective depletion of activated T cells by recombinant immunotoxin containing anti-CTLA-4 single-chain fragment of variable antibody and N-terminal fragment of perforin

We constructed a novel immunotoxin, hS83P34, by fusing the fragment containing the N-terminal 34 amino acids of human perforin to the C-terminal of humanized anti-CTLA-4 single chain fragment of variable antibody. In vitro cytotoxicity assays demonstrated that CTLA-4-positive activated human T cells and 6T-CEM were sensitive to hS83P34, while CTLA-4-negative resting T cells and endothelial cell ECV-304 were resistant to hS83P34. The IC50s of hS83P34 for activated T cells and 6T-CEM were about 0.2 micromol/L and 1.0 micromol/L, there was no obvious cytotoxicity of ECV-304 as detected at 8 micromol/L of hS83P34. In tumor graft rejection models, after treatment with 1.2 mg/kg immunotoxin every day for 12 days, the transplanted tumor cells were rescued by immunotoxin. The tumor weights of grafts of the rejection control group, nonrejection control group, and test group were 0.006 +/- 0.014 g, 0.261 +/- 0.048 g, and 0.135 +/- 0.056 g, respectively. In the early 3 days posttransplantation, there were a lot of CD4- and CD8-positive T cells infiltrating into the tumor grafts of the rejection control group, while only a few T cells were detected in the tumor grafts of the test group. According to these results, we concluded that immunotoxin hS83P34 selectively depleted activated T cells in vitro as well as in vivo in an acute rejection model.     

Complement activation in acute humoral renal allograft rejection: diagnostic significance of C4d deposits in peritubular capillaries.

The distinction between acute humoral rejection (AHR) and acute cellular rejection (ACR) in renal allografts is therapeutically important, but pathologically difficult. Since AHR is probably mediated by antibodies to the donor endothelium that activate the classical complement pathway, it was hypothesized that peritubular capillary C4d deposition might distinguish this group. Renal biopsies (n = 16) from 10 patients with AHR who had acute graft dysfunction, neutrophils in peritubular capillaries, and a concurrent positive cross-match were stained for C4d by immunofluorescence. Control biopsies for comparison showed ACR (n = 14), cyclosporin A toxicity (n = 6), or no abnormality (n = 4). Peribiopsy sera were tested for anti-donor HLA antibody. C4d deposited prominently and diffusely in the peritubular capillaries in all AHR biopsies (16 of 16). IgM and/or C3 were also present in 19 and 44%, respectively. With two-color immunofluorescence, C4d was localized in basement membranes (type IV collagen+) and in the endothelium (Ulex europaeus agglutinin-I+). In ACR, no more than trace C4d was found in peritubular capillaries (P < 0.0001 versus AHR), and no patient had anti-donor HLA antibodies (0 of 8); 27% had neutrophils in peritubular capillaries. One of six biopsies with cyclosporin A toxicity had similar C4d deposits, and circulating anti-donor class I antibody was detected. Grafts with AHR were lost (40%) more often than those with ACR (0%; P < 0.02). C4d in peritubular capillary walls distinguishes AHR from ACR, is more specific and sensitive than traditional criteria, and is a potentially valuable adjunct in the diagnosis of graft dysfunction.     

A New Diagnostic Algorithm for Antibody‐Mediated Microcirculation Inflammation in Kidney Transplants

We studied the significance of microcirculation inflammation in kidney transplants, including 329 indication biopsies from 251 renal allograft recipients, who were mostly nonpresensitized (crossmatch negative). Glomerulitis (g) and peritubular capillaritis (ptc) were often associated with antibody‐mediated rejection (65% and 75%, respectively), but were also found in other diseases in the absence of donor‐specific antibody (DSA): T‐cell‐mediated rejection (ptc, g), glomerulonephritis (g) and acute tubular necrosis (ptc). To develop rules for reducing the nonspecificity of microcirculation inflammation and defining the best grading thresholds associated with DSA, we built and validated a decision tree to predict DSA. The decision tree revealed that g + ptc sum (addition of g‐score plus ptc‐score) was the best predictor of DSA, followed by time posttransplant, then C4d, which had a small role. Late biopsies with g + ptc > 0 showed higher frequency of DSA compared to early biopsies with g + ptc > 0 (79% vs. 27%). Microcirculation inflammation in early biopsies was often false positive (antibody‐independent). The decision tree predicted DSA with higher sensitivity and accuracy than C4d staining. Microcirculation inflammation sum score predicted graft failure independently of time, C4d and transplant glomerulopathy. Thus any degree of microcirculation inflammation in late kidney transplant biopsies strongly indicates presence of DSA and predicts progression to graft failure.     

Expression of activation markers,HLA class II and IL-2R in acute vascular rejection of human renal allografts

We analyzed the expression of class II antigens on graft tubular cells and the expression of IL-2R on lymphoid cells in 314 prospective aspiration biopsies taken from 30 consecutive patients with histologically verified acute vascular rejection (AVR). Based on histology, two main groups were seen: 11 grafts had features of AVR only and 19 grafts had a combination of AVR and acute cellular rejection (ACR). The AVR findings were also predominant in the latter group. In the grafts with a combination of AVR and ACR, patterns similar to ordinary ACR were seen in class II and IL-2R expression. On the contrary, no class II or IL-2R induction could be seen in the grafts with pure AVR and irreversible rejection. This pattern, demonstrated by immunocytology, suggested that AVR is a heterogenous group of rejections, where different cellular and molecular mechanisms are operating. Humoral mechanisms might be involved in these rejections.     

Characterization of CD4, CD8, CD56 positive lymphocytes and C4d deposits to distinguish acute cellular rejection from recurrent hepatitis C in post-liver transplant biopsies

INTRODUCTION: Hepatitis C viral (HCV) infection is the most common cause for liver transplantation (LTx) in USA. Hepatitis C viral recurrence in liver allograft is almost universal, which is often difficult to distinguish from acute cellular rejection (ACR). AIM: Aim of the present study is to examine the differences between distribution of CD4, CD8, CD56 positive lymphocytes, and C4d deposits in patients with ACR and recurrent HCV. PATIENTS AND METHODS: As a pilot project, a group of five post-LTx HCV RNA negative patients, strongly suspicious for ACR based on clinical findings and history of medication non-compliance and another group of five post-LTx HCV positive, medication compliant patients with abnormal liver function were retrospectively selected. Liver biopsies of these patients were stained with monoclonal CD4, CD8, CD56, and polyclonal C4d antibodies and compared. RESULTS: Mean CD4, CD8, and CD56 counts in ACR group were 156.7 +/- 17.6, 35.4 +/- 8.8, and 1.0 +/- 1.8/HPF, respectively and were 89.7 +/- 41.3, 20.3 +/- 23.2, and 0.6 +/- 0.9/HPF, respectively in HCV recurrence group. Biopsies of four of five patients with ACR demonstrated moderate to strong C4d staining, whereas all patients with recurrent HCV had none to mild C4d staining. CONCLUSION: Mean CD4, CD8, and CD56 were similar for acute rejection and recurrent HCV infection. However, 80% of patients with ACR showed moderate to strong staining for C4d and all recurrent HCV patients showed none to mild C4d staining.     

Cytomegalovirus infection and graft rejection in renal transplantation

BACKGROUND: Cytomegalovirus (CMV) infection and CMV disease have been associated with acute and chronic graft rejection. The introduction of the sensitive CMV antigenemia pp65 assay for detection of CMV infection allowed us to study the time course of CMV infection and acute rejection and the long-term outcome in renal transplant recipients with and without a CMV risk constellation. METHODS: Prospective single center study including 48 renal transplant recipients at risk for CMV infection (donor and/or recipient CMV seropositive) and a control group of 36 CMV seronegative recipients of CMV seronegative kidney donors. Evidence of CMV infection was monitored by the CMV antigenemia pp65 assay every 1 to 2 weeks and compared with the occurrence of acute rejection in the posttransplant period and graft function at 5 years. RESULTS: CMV infection developed in 83% (40/48) of patients of the CMV risk group within 4 months posttransplant. A total of 18 of patients experienced an acute rejection episode (control group 16/36; P=0.65). In 12/18 CMV infection followed rejection and in three patients antigenemia preceded the diagnosis of rejection. In three patients CMV antigenemia remained negative. Five-year follow up: Patient survival (44/48 vs. 31/36; P=0.48), graft survival (38/48 vs. 27/36; P=0.79), number of patients with at least one acute rejection episode: CMV risk group: 42.1%, control group 51% (P=0.46), serum creatinine: CMV risk group:130 +/- 66 micromol/iter, control group: 126 +/- 37 micromol/ liter (P=0.56), proteinuria: CMV risk group: 0.02 +/- 0.02 g/mmol creatinine, control group: 0.02 +/- 0.02 g/mmol creatinine (P=1.0). CONCLUSION: CMV infection within 4 months posttransplant, as defined by a positive antigenemia assay was not found to be a risk factor for acute graft rejection or chronic graft dysfunction at 5 years.     

Prediction of chronic allograft damage index of renal allografts using serum level of plasminogen activator inhibitor‐1

Abstract: Background: Plasminogen activator inhibitor‐1 (PAI‐1) plays an important role in renal fibrosis. We conducted this study to examine whether serum PAI‐1 has a role in predicting chronic allograft nephropathy (CAN). Methods: Fifty kidney transplant recipients receiving graft biopsies were enrolled. The pathologic diagnoses were acute tubular necrosis (ATN; n = 12), borderline rejection (BR; n = 7), acute rejection (ACR; n = 12), CAN (n = 11), polyomavirus nephropathy (PVN; n = 3) and others (n = 5; glomerulopathy, n = 4; calcineurin inhibitor nephropathy, n = 1). The serum level of PAI‐1 and chronic allograft damage index (CADI) score of each patient were determined. Results: The CADI score of all patients was 4 (0–10) (median and range) and in each group was ATN 0.5 (0–4), BR 2.0 (1–4), ACR 4.0 (2–8), CAN 5.0 (4–10), PVN 7 (4–8) and others 2 (0–8). The serum PAI‐1 level of each group was ATN 9.38 (2.35–14.52) ng/mL, BR 10.09 (0.61–18.06) ng/mL, ACR 11.08 (2.32–20.68) ng/mL, CAN 14.51 (3.66–21.12), PVN 14.79 (13.94–21.94) and others 16.35 (4.05–21.01) ng/mL. CADI score is associated with serum PAI‐1 activity (r = 0.405, p = 0.003) and is inversely associated with serum creatinine (r = ?0.348, p = 0.011), but not with estimated glomerular filtration rate (p = 0.124). Conclusion: Serum PAI‐1 level has the potential to be a marker to predict CADI score, the quantitative score of CAN.     

The PlA2 polymorphism of the platelet glycoprotein IIIA gene as a risk factor for acute renal allograft rejection

Glycoprotein IIIa/IIb is a membrane receptor for fibrinogen and von Willebrand factor that plays an important role in platelet aggregation. The beta integrin chain of this receptor, GPIIIa, is polymorphic, and the allele known as PlA2 has been associated with coronary thrombosis. The GPIIIa genotype of a cohort of 119 consecutive renal allograft recipients (46.3 +/- 13 yr; 85 M/34 F; 24.4% diabetic patients) was determined by PCR-restriction fragment length polymorphism, and those patients were followed for at least 12 mo. From 119 patients with at least 1 yr of follow-up, those who suffered an acute rejection (n = 52) showed a lower proportion of HLA-DR beta1 identity with the donor (7.7% versus 23.9%; P = 0.03), a higher proportion of cytomegalovirus-positive (CMV+) donors/CMV- recipients (21% versus 7.5%; P = 0.05), and the PlA2 allele was more frequent (48.1% versus 26.9%; P = 0.02) compared with patients free of acute rejection (n = 67). No other variable was associated with acute rejection in the univariate analysis. The impact of the three above-mentioned significant variables on acute rejection was analyzed by stepwise logistic regression. The presence of the PlA2 allele yielded an odds ratio of 2.75 (95% confidence interval, 1.01 to 7.93) and an HLA-DR beta1 identity of 0.2 (95% confidence interval, 0.06 to 0.99) for suffering an acute rejection episode. In addition, the serum creatinine at discharge was higher in PlA2-positive versus PlA2-negative patients (2.2 +/- 1.6 versus 1.5 +/- 0.6 mg/dl, respectively; P = 0.01), and the prevalence of proteinuria >1.5 g/d 1 yr after transplantation was significantly higher among patients showing the PlA2 allele (16% versus 3%; P = 0.02). Finally, in the entire cohort of patients, the 2-yr graft survival was significantly lower in PlA2-positive (n = 43) compared with PlA2-negative (n = 76) patients (85.7% versus 97.2%; P = 0.015). No differences were found in patient survival (95.2% versus 98.7%, respectively). Proportional hazards regression analysis (Cox regression model) confirmed that serum creatinine level at discharge is the best predictor of allograft survival, followed by CMV status, delayed graft function, and the glycoprotein IIIa/IIb genotype. The PlA2 polymorphism is an independent risk factor for acute renal graft rejection, affecting short-term graft survival. Future studies aimed at preventing the hemostatic imbalance favoring platelet aggregation associated with this polymorphism may be important in preventing acute rejection and its impact on chronic rejection.     

Association of CD20+ Infiltrates with Poorer Clinical Outcomes in Acute Cellular Rejection of Renal Allografts

We undertook a study to ascertain the relationship between the presence of CD20-positive B-lymphocytes in renal allografts undergoing acute cellular rejection and graft survival. We identified 27 patients transplanted between January 1, 1998 and December 31, 2001, with biopsy-proven Banff 1-A or Banff 1-B rejection in the first year after transplantation, and stained the specimens for CD20 and C4d. At least 4 years of follow-up data were available for each patient studied. Six patients had CD20-positive B-cell clusters in the interstitium, and 21 patients were negative for CD20 infiltrates. The CD20-positive group was significantly more likely to have steroid-resistant rejection and reduced graft survival compared to CD20-negative controls. This study supports prospective identification of CD20-positive B-cell clusters in biopsy-proven rejection and offers a therapeutic rationale for a trial of monoclonal anti-CD20 antibody in such patients.     

Detection of anti-HLA antibody by flow-cytometric panel reactive antibody in kidney transplant recipient with frequent episodes of acute rejection

Abstract:  A 43-yr-old woman with end-stage renal disease caused by lupus nephritis received living kidney transplantation with ABO minor mismatch from her mother. Urine output decreased rapidly from fifth postoperative day, and serum creatinine (sCr) concentration increased rapidly. The clinical diagnosis was antibody-mediated rejection. The patient was treated with pulse methylprednisolone, plasma exchange (PEX), and OKT3. A graft biopsy revealed vascular rejection with linear C4d deposition on peritubular capillary (PTC). She was treated with additional PEX and intravenous cyclophosphamide, which improved urine output and resulted in a gradual decrease in sCr. She subsequently developed frequent episodes of acute rejection (AR) with a rise in sCr. Repeated graft biopsies revealed acute T-cell-mediated rejection with progressive interstitial fibrosis and tubular atrophy. Severe peritubular capillaritis with mononuclear infiltrates were present, but C4d deposition on PTC was persistently negative or weak. Flow-cytometric panel reactive antibody performed retrospectively revealed both donor- and non-donor-specific HLA antibodies, which were persistently present after the treatment of the first AR. We added rituximab to the treatment of AR, but she developed cytomegalovirus enteritis, and eventually hemodialysis was induced again 45 months after the transplantation. Recent flow-cytometry-based antibody detection methods are useful even in cases lacking diffuse and strong C4d deposition on PTC.     

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

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

Acute renal allograft rejection is associated with increased levels of vascular endothelial growth factor in the urine

AIM: The purpose of this study was to assess whether measurement of urinary vascular endothelial growth factor (VEGF) could be adopted as a new non-invasive diagnostic tool for acute rejection following renal transplantation. METHODS: Urinary concentration of VEGF was determined by an enzyme-linked immunosorbent assay technique in 215 renal allograft recipients and 80 healthy controls. RESULTS: Subjects with acute rejection (n=67) excreted urinary VEGF at a significantly higher level (28.57+/-6.21, 95% CI: 16.18-40.97 pg/mumol creatinine) than those without acute rejection. This included subjects with stable renal function and no abnormal histological findings (n=119), acute tubular necrosis (n=15), chronic allograft nephropathy (n=14) and healthy controls (n=80). Using a urinary VEGF/creatinine ratio of 3.64 pg/micromol as the cut-off point, the sensitivity and specificity for diagnosing acute rejection were 85.1 and 74.8%, respectively (P<0.001). Patients with steroid-resistant acute rejection had significantly greater urinary VEGF concentration than patients with steroid-sensitive acute rejection (42.09+/-10.00 vs 9.74+/-2.63 pg/micromol creatinine, P<0.001). Patients with graft loss after acute rejection had significantly greater urinary VEGF concentration than patients with reversible acute rejection (106.66+/-38.60 vs 19.46+/-4.13 pg/micromol creatinine, P=0.001). Using a urinary VEGF/creatinine ratio of 22.48 pg/micromol as the cut-off point, the sensitivity and specificity of the prediction to graft loss after acute rejection were 85.7% and 78.3%, respectively (P=0.001). CONCLUSION: This study demonstrates that the monitoring of urinary VEGF may be a useful non-invasive approach for the detection of acute rejection. Additionally, urinary VEGF levels were shown to predict the response to anti-rejection therapy and to predict a poor outcome after acute rejection.     

Expression of ICAM-1 and HLA class II in acute cellular and vascular rejection of human kidney allografts

Abstract We studied the relationship between ICAM-1 and class II expression on graft tubular cells and the relationship with graft inflammation in 50 kidney transplants monitored with serial aspiration biopsies after transplantation. Of the 50 grafts, 26 had an acute rejection 17 ± 10 days after transplantation, 5 also had acute vascular rejection (AVR) and 24 had no rejection. The initial post-transplant ICAM-1 and class II expression was low in all grafts. All 21 grafts with acute cellular rejection (ACR) displayed ICAM-1 induction, with a peak at the beginning of acute blastogenic rejection and declining over 20 days to prerejection levels. Class II expression reached a peak later and also declined later to prerejection levels. In the grafts with irreversible AVR both ICAM-1 and class II expression remained elevated. The 24 grafts with no rejection displayed no ICAM-1 or class II induction on tubular cells during the follow-up. The differences between ICAM-1 and classs II expression in biopsies with rejection and with no rejection were statistically significant. The results demonstrate that ICAM-1 was induced early during ACR on the graft tubular cells and that it disappeared rapidly in reversible rejections. The induction of class II antigens was slightly slower but quantitatively greater. In the irreversible rejections with a combination of ACR and AVR both ICAM-1 and class II expression remained elevated.     

Clinical and pathological assessment of acute vascular rejection in the transplant kidney

Koike J, Yamaguchi Y, Horita S, Tanabe K, Fuchinoue S, Toma H, Nihei H. Clinical and pathological assessment of acute vascular rejection in the transplant kidney. Clin Transplantation 2001: 15 (Supplement 5): 41–44. ©Munksgaard, 2001
Acute vascular rejection (AVR) in kidney transplan- tation is the most important factor influencing graft prognosis. We focus on patients whose grafts were lost because of AVR, and assessed their clinical characteristics and histological findings of biopsied renal grafts. Biopsied specimens exhibited AVR in 43 patients who underwent kidney transplantation in the Kidney Center of Tokyo Women's Medical University from 1995 to 1999. In the follow-up from 1 to 5 yr (median: 2.5 yr) we classified these patients into three groups: favourable prog- nosis group (FPG), relatively poor prognosis group (RPPG) and poor prognosis group (PPG). Light microscopic study for histological grading of acute rejection according to the Banff scheme and detection of the C4d complement deposition on peritubular capillaries by the immunofluorescence method were performed. Based on the results, the donors of RPPG and PPG were significantly older than those of FPG, and all factors of acute rejection according to the Banff scheme were not statistically significantly different among the three groups. However, an acute tubular injury mimicking acute tubular necrosis (ATN) was observed in the biopsy specimens from PPG. In conclusion, an older donor is a risk factor of poor prognosis of the graft with AVR, and acute tubular injury mimicking ATN is one of the important features that enables the prediction of graft failure originating from AVR in kidney transplantation.