Determination of unacceptable HLA antigen mismatches in kidney transplant recipients: recommendations of the German Society for Immunogenetics.

One of the major tasks of histocompatibility and immunogenetics laboratories is the pretransplant determination of unacceptable antigen mismatches (UAM) in kidney transplant recipients. In this procedure, human leucocyte antigen (HLA) specificities are defined against which the patient has circulating alloantibodies that are expected to harm the transplanted organ. Using the information on UAM and the potential donor's complete HLA typing, prediction of the crossmatch result, the so called 'virtual crossmatch', is possible. Currently, the laboratories are using different algorithms for the determination of UAM, and depending on the algorithm, more or fewer organ offers are excluded for patients with a similar antibody profile. In order to bring homogeneity into the allocation of organs to immunized patients in Germany, the German Society for Immunogenetics established, on the basis of current knowledge, recommendations for the determination of UAM. The UAM recommendations, which are thought to serve as a common tool for responsible physicians at different transplant centers, contain technical issues that need to be considered and are individualized for sensitized patients with a high or intermediate risk of antibody-mediated rejection. The present review contains these recommendations and puts them into perspective to current international practice.

Human pregnane X receptor genotype of the donor but not of the recipient is a risk factor for delayed graft function after renal transplantation.

Delayed graft function (DGF) is an important complication in renal transplantation, contributing significantly to decrease in long-term allograft survival. In addition to donor- and recipient-related risk factors such as immunosuppression, altered renal excretion of xenobiotics by membrane transporters may influence DGF. Using DNA samples from recipients and donors, we assessed the impact on DGF of genetic variants in P-glycoprotein (ABCB1), multidrug resistance protein 2 (ABCC2), and the nuclear pregnane X receptor (PXR/NR1I2), which regulates the transcription of enzymes and transporters. In our local cohort of renal transplant recipients (n = 178), DGF occurred in 27.5%. The PXR 8055TT genotype of the donor only (not of the recipient) was significantly associated with an increased risk for DGF. This finding emerged from univariate as well as multivariate logistic regression analysis including 16 nongenetic factors and held true after correction for multiple testing. Our findings provide the first evidence that PXR may be associated with risk of DGF, independent of previously identified risk factors.

A Pneumocystis jirovecii pneumonia outbreak in a single kidney-transplant center: role of cytomegalovirus co-infection.

Pneumocystis jirovecii pneumonia (PCP) and cytomegalovirus (CMV) infection represent possible complications of medical immunosuppression. Between 2005 and 2010, non-human immunodeficiency virus (HIV) PCP patients admitted to a nephrology unit were analyzed for outcome, CMV comorbidity, and patient-to-patient contacts prior to PCP. In contrast to 2002-2004 (no cases) and 2008-2010 (10 cases), a PCP outbreak of 29 kidney-transplant recipients and one patient with anti-glomerular basement membrane disease occurred between 2005 and 2007. None of the patients were on PCP chemoprophylaxis. In four PCP patients, the genotyping data of bronchoalveolar lavage specimen showed an identical Pneumocystis strain. PCP cases had a higher incidence of CMV infection (12 of 30 PCP patients) and CMV disease (four patients) when compared to matched PCP-free controls (p < 0.05). Cotrimoxazole and, if applicable, ganciclovir were started 2.0 ± 4.0 days following admission, and immunosuppressive medication was reduced. In-hospital mortality was 10% and the three-year mortality was 20%. CMV co-infection did not affect mortality. CMV co-infection more frequently occurred during a cluster outbreak of non-HIV PCP in comparison to PCP-free controls. Here, CMV awareness and specific therapy of both CMV infection and PCP led to a comparatively favorable patient outcome. The role of patient isolation should be further investigated in incident non-HIV PCP.

The Primavera study protocol design: evaluating the effect of continuous erythropoiesis receptor activator (C.E.R.A.) on renal function in non-anemic patients with chronic kidney disease.

Erythropoiesis stimulating agents (ESA) are widely used for hemoglobin correction in patients suffering from renal anemia. However, their beneficial non-hematopoietic effects on renal deterioration have not been adequately assessed. The Primavera study is the first prospective, controlled trial to assess whether ESA treatment could ameliorate progression of chronic kidney disease (CKD) in non-anemic patients. Primavera is a single-blind, 24-month trial in which patients are randomized to placebo or to C.E.R.A., a continuous erythropoietin receptor activator. Patients with type 2 diabetes or who have undergone kidney transplantation are eligible to enter the study if they have CKD stage III (estimated GFR [eGFR] 30-59 mL/min/1.73 m(2)), urinary albumin to creatinine ratio (UACR) ≥ 50 g/g and ≤ 1500 g/g, or total urine protein ≥ 50mg/24h and ≤ 1500mg/24h, and hemoglobin 11-14 g/dL. The primary efficacy endpoint is the change in eGFR from baseline to month 24. Secondary efficacy endpoints are the changes in UACR, serum cystatin C and serum creatinine from baseline. Safety endpoints include adverse events and discontinuation due to pre-specified adverse events. An interim analysis will be performed after all patients have completed the first year. The planned sample size is 400 patients (200 type 2 diabetics, 200 transplant recipients) conferring 90% power to detect a prespecified significant difference of 1.5 mL/min/1.73 m(2) in the annual reduction in eGFR between treatment groups. The results of Primavera are expected in 2013.

Can the preprocurement pancreas suitability score predict ischemia-reperfusion injury and graft survival after pancreas transplantation?

BACKGROUND: Ischemia-reperfusion injury (IRI) is common after pancreas transplantation, leading to pancreatitis or thrombosis with the need for relaparotomy or even graft loss. Optimal donor selection may reduce the postoperative morbidity of IRI. The Eurotransplant preprocurement pancreas suitability score (P-PASS) seeks to identify ideal donors with a value <17. Owing to the organ shortage the waiting time for pancreas transplantation is increasing, a problem that may be addressed with the use of extended-criteria donors. We analyzed our pancreas transplantations regarding postoperative complications according to the P-PASS. To reflect IRI we used the peak C-reactive protein (CRP) levels during the first 3 postoperative days. METHODS: From January 2009 to July 2010, we transplanted 52 pancreas grafts, including, 50 simultaneous pancreas-kidney transplantations (SPK), 1 after a kidney graft, and 1 alone. For 3 SPK donors the P-PASS was not available. All transplantations were performed using systemic venous and enteric drainage. The immunosuppression protocol included antibody induction with antithymocyte globulin and maintenance therapy with steroids, tacrolimus, and mycophenolate mofetil. The peak CRP in the first 3 postoperative days was used as a marker for IRI. RESULTS: The mean P-PASS of our donors was 16.4 ± 2.6 (range, 12-22). We compared 24 patients receiving organs from "ideal" donors (P-PASS <17; ID) with 25 receiving grafts from extended-criteria donors (P-PASS ≥17; ED). There was no significant difference in the incidence of graft loss among ID versus ED grafts (20.8% vs 20.0%; P = 1.0). Comparing the rates of postoperative complications of patients, we did not observe a significant difference in graft thrombosis (4.2% vs 16.0%; P = .349), relaparotomy (29.2% vs 40.0%; P = .551), a pancreatic fistula (37.5% vs 28.0%; P = .543), or the length of hospital stay (36.5 ± 19.2 vs 37.4 ± 20.8 days; P = .875), respectively. Regarding IRI, there was no significant difference in peak CRP values (14.1 ± 5.5 vs 16.2 ± 6.0 mg/dL; P = .211). CONCLUSION: This single center analysis failed to show that P-PASS significantly predicted pancreas graft survival, postoperative morbidity, or IRI severity. These findings suggested a chance to increase the donor pool using extended-criteria donors.

Incidence and treatment of pancreatic fistula after simultaneous pancreas kidney transplantation.

BACKGROUND: Simultaneous pancreas and kidney transplantation (SPK) is associated with great postoperative morbidity, including the need for relaparotomy in up to 40% of cases. Because the pancreatic graft is known to be the major cause of the high morbidity, we examined the incidence and treatment of pancreatic fistula (PF) in this retrospective analysis. METHODS: From January 2004 to July 2010, we transplanted 52 pancreas grafts, including 50 SPK, 1 pancreas after kidney, and 1 pancreas transplantation alone. There were 22 female and 30 male patients with an overall mean age of 42.4 ± 7.4 years. The mean duration of diabetes was 27.3 + 8.1 years, mean duration of dialysis was 24.2 ± 28.6 months, and 14 cases were pre-emptive transplantations. All procedures were performed using systemic venous and enteric drainage. RESULTS: The incidence of clinically relevant PF was 16/52 (30.8%), including 11 (68.8%) that were treated conservatively with a drain. Five patients (31.2%) needed relaparotomy: 2 due to enteric leakage, 2 due to acute abdominal pain with graft pancreatitis observed at laparotomy, and 1 due to acute hemorrhage. In 3 cases, graft pancreatectomy was necessary. Comparing the patients with (PF+) versus without (PF-) fistulas, there was no significant difference in cold ischemia time (10.9 ± 2.6 hours vs 10.4 ± 4.4 hours; P = .633), donor age. We found a significantly higher peak C-reactive protein (CRP) level in the patients with pancreatic fistula (3661.4 ± 3474.8 U/L vs 821.8 ± 1293.7 U/L, P = .022). The lipase concentration measured in the drainage fluid postoperatively showed a significant difference between the 2 groups (3661.4 ± 3474.8 U/L vs 821.8 ± 1293.7 U/L; P = 0.006). Also, the amylase concentration was higher in the PF+ group (1747.3 ± 3346.7 U/L vs 265.3 ± 254.9 U/L; P = .097). Graft loss occurred in 4/16 cases (25.0%) of PF+ and 7/36 (19.4%) of PF- (P = .719). CONCLUSION: The incidence of PF after pancreas transplantation is high and seems to be associated with ischemia-reperfusion injury reflected by peak-CRP. In most cases a conservative treatment is successful. The occurrence of a PF does not significantly impair graft survival.

The efficacy and safety of 200 days valganciclovir cytomegalovirus prophylaxis in high-risk kidney transplant recipients.

Late-onset cytomegalovirus (CMV) disease is a significant problem with a standard 3-month prophylaxis regimen. This multicentre, double-blind, randomized controlled trial compared the efficacy and safety of 200 days' versus 100 days' valganciclovir prophylaxis (900 mg once daily) in 326 high-risk (D+/R-) kidney allograft recipients. Significantly fewer patients in the 200-day group versus the 100-day group developed confirmed CMV disease up to month 12 posttransplant (16.1% vs. 36.8%; p < 0.0001). Confirmed CMV viremia was also significantly lower in the 200-day group (37.4% vs. 50.9%; p = 0.015 at month 12). There was no significant difference in the rate of biopsy-proven acute rejection between the groups (11% vs. 17%, respectively, p = 0.114). Adverse events occurred at similar rates between the groups and the majority were rated mild-to-moderate in intensity and not related to study medication. In conclusion, this study demonstrates that extending valganciclovir prophylaxis (900 mg once daily) to 200 days significantly reduces the incidence of CMV disease and viremia through to 12 months compared with 100 days' prophylaxis, without significant additional safety concerns associated with longer treatment. The number needed to treat to avoid one additional patient with CMV disease up to 12 months posttransplant is approximately 5.

Treatment of PTLD with rituximab and CHOP reduces the risk of renal graft impairment after reduction of immunosuppression.

We addressed the effect of post-transplant lymphoproliferative disorder (PTLD) treatment with rituximab monotherapy or CHOP-based chemotherapy (+/- rituximab) after upfront immunosuppression reduction (IR) on renal graft function in a longitudinal analysis of 58 renal transplant recipients with PTLD and 610 renal transplant controls. Changes in the estimated glomerular filtration rate over time were calculated from a total of 6933 creatinine measurements over a period of >1 year using a linear mixed model with random and fixed effects. Renal graft function significantly improved with treatment of PTLD, especially in the chemotherapy subgroup. Patients treated with IR+chemotherapy +/- rituximab had a noninferior graft function compared with untreated controls suggesting that the negative impact of IR on the renal graft function can be fully compensated by the immunosuppressive effect of CHOP. The immunosuppressive effect of single agent rituximab may partially compensate the negative impact of IR on the graft function. Thus, it is possible to reduce immunosuppression when using chemotherapy to treat PTLD.

Remission of a B cell CLL-associated membranoproliferative glomerulonephritis Type I with rituximab and bendamustine.

In a 56-year-old white male patient, a membranoproliferative glomerulonephritis Type I was diagnosed after a 12-month history of low grade B cell lymphoma (Binet A). HIV, Hepatitis B and C serology were negative. Due to an impairment of renal function despite chemotherapy with COP, an immunochemotherapy consisting of rituximab (6 cycles) and bendamustine (4 cycles) was given. This therapeutic approach caused a complete remission of the nephrotic syndrome. Renal function and arterial hypertension improved markedly. In addition, urinary sediment became normal and proteinuria disappeared completely.

A randomized, multicenter study of steroid avoidance, early steroid withdrawal or standard steroid therapy in kidney transplant recipients.

In a randomized, open-label, multicenter study, de novo renal transplant patients received no steroids (n = 112), steroids to day 7 (n = 115), or standard steroids (n = 109) with cyclosporine microemulsion (CsA-ME), enteric-coated mycophenolate sodium (EC-MPS) and basiliximab. The primary objective, to demonstrate noninferiority of 12-month GFR in the steroid-free or steroid-withdrawal groups versus standard steroids, was not met in the intent-to-treat population. However, investigational groups were not inferior to standard steroids in the observed-case analysis. Median 12-month GFR was not significantly different in the steroid-free or steroid-withdrawal groups (58.6 mL/min/1.73 m(2) and 59.1 mL/min/1.73 m(2)) versus standard steroids (60.8 mL/min/1.73 m(2)). The 12-month incidence of biopsy-proven acute rejection (BPAR), graft loss or death was 36.0% in the steroid-free group (p = 0.007 vs. standard steroids), 29.6% with steroid withdrawal (N.S.) and 19.3% with standard steroids. BPAR was significantly less frequent with standard steroids than either of the other two regimens. Reduced de novo use of antidiabetic and lipid-lowering medication, triglycerides and weight gain were observed in one or both steroid-minimization group versus standard steroids. For standard-risk renal transplant patients receiving CsA-ME, EC-MPS and basiliximab, steroid withdrawal by the end of week 1 achieves similar 1-year renal function to a standard-steroids regimen, and may be more desirable than complete steroid avoidance.

IL-18 is expressed in the intercalated cell of human kidney.

We determined the cellular location of interleukin-18 (IL-18) and caspase-1 and the purinergic receptor P2X7, two proteins necessary for its activation and secretion. The mRNA and protein of IL-18 were detectable in normal human kidney by means of polymerase chain reaction (PCR), in situ hybridization, and Western blot. Immunohistochemistry located IL-18 to nephron segments containing calbinbin-D28k or aquaporin-2 that suggest location in the distal convoluted and the connecting tubule and to parts of the collecting duct. IL-18 was not detected in the thick ascending limb of Henle. Confocal microscopy showed that IL-18 was expressed in cells negative for calbindin-D28k and for aquaporin-2 but positive for the vacuolar H(+)-ATPase. This demonstrates that the intercalated cells produce IL-18. These segments were also positive for caspase-1 and P2X7 that are essential for IL-18 secretion. Our results show that IL-18 is constitutively expressed by intercalated cells of the late distal convoluted tubule, the connecting tubule, and the collecting duct of the healthy human kidney. Since IL-18 is an early component of the inflammatory cytokine cascade, its location suggests that renal intercalated cells may contribute to immediate immune response of the kidney.

[Quality of kidney procurement in Germany. Ten years experience and 486 renal allografts in a single centre]. / Qualität der Leichennierenentnahme in Deutschland. 10-Jahres-Erfahrungen mit 486 transplantierten Leichennieren an einem Zentrum.

BACKGROUND: Organ damage during organ procurement is believed to be an increasing problem among transplant centres. However, only very few published data are available. The purpose of our study was to examine the quality of kidney procurement in Germany. METHODS: We retrospectively analyzed all allograft renal transplants performed at our centre from 1996 to 2005. All kidneys were retrieved in Germany and allocated by Eurotransplant. RESULTS: From a total of 486 cadaveric kidneys, 103 (21.2%) were not correctly retrieved. Nevertheless, none of the organs had to be rejected. In 18 (3.7%), a technically insufficient organ retrieval was associated with a considerable extension of the surgical procedure or complications. CONCLUSIONS: Technically insufficient kidney procurement rarely results in clinical consequences. However, surgeons performing organ retrieval should be better trained. Whether adequate technical proficiency is achieved with ten supervised cases, as requested by the German Medical Association, remains to be determined. In our opinion, a further interdisciplinary course that trains surgeons in more refined techniques of organ procurement is desirable.

Epstein-barr virus-associated posttransplant lymphoproliferative disorder of donor origin after simultaneous pancreas-kidney transplantation limited to pancreas allograft: A case report.

A 45-year-old man was admitted with fever and elevated pancreas enzymes 6 months after simultaneous pancreas-kidney transplantation (SPKT). Function of the allografts was normal. Bacterial and fungal infections were excluded, while Epstein-Barr virus (EBV)-polymerase chain reaction (PCR) was positive. However, screening for EBV-associated lymphoma was negative. EBV infection did not respond to antiviral therapy. After an 18F-Fluorodeoxyglucose positron emission tomography positive signal and an abnormal computed tomography scan of the pancreas transplant, a biopsy revealed a diffuse large monomorphic B-cell lymphoma, which was confined to the grafted organ. Its origin was assigned to the donor by microsatellite analysis. Reduction of immunosuppression and immunotherapy with rituximab was unsuccessful. After 10 weeks, the patient developed an acute hemolytic uremic syndrome which required explantation of the allografts. Subsequent to the intervention, fever disappeared, EBV DNA became undetectable and lymphoma screening remained negative. In posttransplant lymphoproliferative disorder of donor origin after SPKT, transplantectomy may be a curative therapy.

Evaluation of type 1 diabetics for simultaneous pancreas-kidney transplantation with regard to cardiovascular risk.

The main cause of death for diabetic patients and patients on dialysis is coronary artery disease (CAD). The most common cause of graft loss following simultaneous pancreas and kidney transplantation (SPK) is death with a functioning graft due to CAD. Therefore, careful pretransplantation evaluation of CAD is mandatory. In our series, every patient undergoes a noninvasive cardiac function test like dobutamine stress echocardiography (DSE) or myocardial thallium scintigraphy using adenosine to induce medical stress. Thirty patients were evaluated for SPK: 15 patients with myocardial scintigraphy and 8 with DSE. Seven investigations showed pathological findings and we performed coronary angiograms, none of which showed coronary artery stenosis. Seven primary coronary angiograms were performed: four due to a history of CAD and three as a primary diagnostic. Following SPK one patient died at 21 days after transplantation due to myocardial infarction. He had a history of CAD with angioplasty and stent implantation. Noninvasive cardiac function tests like DSE or myocardial scintigraphy are reliable methods to evaluate CAD in patients with diabetic nephropathy awaiting SPK. In case of a suspicious finding or a history of CAD, a coronary angiogram should be performed to assess the need for revascularization. Following this algorithm we may further reduce the mortality of SPK.

Mechanisms of everolimus-induced glomerulosclerosis after glomerular injury in the rat.

Despite the lack of nephrotoxicity, adverse effects of the new antiproliferative immunosuppressant everolimus have been reported. By varying time point and dose of everolimus treatment as well as the degree of glomerular injury, the specific conditions and potential mechanisms leading to adverse actions in the anti-Thy1 model have been determined. Only the combination of early and high-dose everolimus treatment (1-3 mg/kg bw) with a severe glomerular lesion ('full-dose' anti-Thy1 model) caused adverse effects with a high mortality rate, progressive apoptosis, crescent formation and glomerulosclerosis. In contrast, either later start or low-dose (0.3 mg/kg bw) therapy or treatment of a less severe lesion ('reduced dose' anti-Thy1 model) appeared to be relatively safe for the glomerular architecture. The adverse effects of everolimus were linked to its marked inhibition of endothelial cell, but not necessarily mesangial cell proliferation. In addition, everolimus markedly inhibited the angiogenic cytokine vascular endothelial growth factor in nephritic glomeruli in vivo. These experimental results suggest special caution regarding the use of everolimus in all situations of severe glomerular cell injury requiring extensive capillary repair, where at least adaption to a low dose needs to be considered.

Monitoring of peripheral blood cytotoxic T-cells under fluvastatin treatment in renal transplant recipients.

Flow cytometric T-cell analysis is capable of adding valuable information for balancing immunosuppression in transplant recipients as it can take into account individual effects of immunosuppressive drugs on each patient as well as effects of other drugs which may modify the overall immunosuppression. Studies suggest that HMG-CoA-reductase-inhibitors (statins) reduce the frequency of organ rejection, although the precise mechanism of this effect is unknown. We therefore evaluated the effect of fluvastatin on size and activation of T-cell subpopulations and NK-cell activity in renal transplant recipients. At baseline, the population size of activated (HLA-DR+) T-cells was negatively correlated to serum HDL cholesterol suggesting an increased T-cell activation at low HDL levels. Fluvastatin treatment of a hypercholesterolemic group of patients for two months significantly decreased the LDL cholesterol. A longitudinal analysis revealed a relative increase in non-MHC restricted cytotoxic T-cells (CD3+/CD16+ or CD56+) over time which was significantly attenuated in fluvastatin treated patients but not in normocholesterolemic controls. Moreover, a relative decrease of activated MHC class I-restricted cytotoxic CD8+ T-cells was only observed upon fluvastatin treatment. NK-cell number and activity did not differ between groups. In summary, fluvastatin treatment of hypercholesterolemic renal transplant recipients is associated with a specific modulation of T-cells exerting cytotoxic effector functions.

Clinical aspects of renal transplantation in polycystic kidney disease.

BACKGROUND: Autosomal dominant polycystic kidney disease (ADPKD) as a systemic disorder represents a special subgroup among patients with end-stage renal disease (ESRD). The different organ manifestations are potential risk factors for cardiovascular events or infections in the course after renal transplantation. Therefore, a long-term evaluation of ADPKD patients and of a control group was done. PATIENTS AND METHODS: 80 ADPKD patients were compared with 88 non-diabetic patients in a retrospective follow-up after renal transplantation. Patient and graft survival (1, 5 and 10 years after transplantation) as well as complications such as infections and cardiovascular events were evaluated. RESULTS: A comparable overall transplant (1 year, 5 years, 10 years: 83%, 73%, 67% ADPKD vs. 84%, 70%, 51% controls) and patient survival rate (1 year, 5 years, 10 years: 96%, 84%, 73% ADPKD vs. 91%, 79%, 58% controls) was found in both groups. Infectious complications with the exception of urinary tract infections (UTIs: ADPKD 42.5% vs. 26%) were diagnosed in similar frequency in the graft recipients. ADPKD patients were significantly more affected by UTIs than their control group (p < 0.05) and tended to suffer more often from lethal infections (ADPKD 7 vs. controls 3), but without statistical significance. Cardiovascular events were not observed to be significantly different between both groups (ADPKD 3 vs. controls 4). An obvious difference was found in patient (p < 0.01) and transplant survival rates (p < 0.05) of male and female ADPKD patients. The female group showed a significantly better outcome. CONCLUSIONS: The overall patient and graft survival rates did not differ between the ADPKD and control groups. The better outcome of female ADPKD graft recipients compared to the male group may be related to a gender-dependent disease severity, possibly due to hormonal effects. As UTIs and lethal septicemia were the leading complications in ADPKD patients, a careful monitoring for infections is important in the post-transplant follow-up.

Differential inhibitory effects of intravenous immunoglobulin preparations on HLA-alloantibodies in vitro.

BACKGROUND: Treatment of allosensitized patients with intravenously administered pooled immunoglobulin preparations (IVIG) may lead to a long-lasting reduction of anti-HLA alloantibody titers. An inhibitory response of IVIG preparations on lymphocytotoxicity is suggested to depend on IgG and to predict a successful reduction of anti-HLA alloantibodies upon the administration of high-dose IVIG in vivo. METHODS: In this study, we evaluated different IVIG preparations for their in vitro inhibitory capacity on lymphocytotoxicity and binding of anti-HLA alloantibodies to purified HLA antigens. For that purpose sera from 24 highly sensitized patients awaiting kidney transplantation and serological HLA testing reagents were used. Panel-reactive antibody (PRA) determinations using standard complement-dependent cytotoxicity testing and anti-HLA alloantibody determination by ELISA were carried out in the presence and absence of 50% (v/v) IVIG. RESULTS: The addition of IgG-containing IVIG preparations gave only a moderate inhibitory response judging from the average decrease of PRA levels (absolute DeltaPRA range: -2% to 16%), whereas the largest inhibition of lymphocytotoxicity was seen after the addition of IgM/IgA-containing IVIG preparations (absolute DeltaPRA range: 19% to 44%). For both IgG and IgM/IgA-containing IVIG preparations, the reduction of lymphocytotoxicity occurred in a dose-dependent fashion without a preference for particular anti-HLA class I antibody specificities. Significantly lower inhibitory effects on anti-HLA antibody reactivity were observed when the effects of IVIG preparations were monitored by ELISA (absolute DeltaPRA range: 7% to 22%). CONCLUSIONS: Our data suggest that the immunomodulatory capacity is largely caused by the IgM/IgA fraction of IVIG when analyzed by lymphocytotoxicity. The different effect on ELISA versus complement-dependent cytotoxicity testing suggests that interactions of IVIG with complement rather than anti-idiotypic antibodies may contribute to the inhibitory effects of IVIG in vitro.

Expression of multidrug resistance P-glycoprotein in kidney allografts from cyclosporine A-treated patients.

BACKGROUND: The multidrug resistance (MDR) gene product P-glycoprotein (P-gp) is a transmembrane efflux pump for hydrophobic, potentially toxic compounds, including the immunosuppressant cyclosporine A (CsA). We have previously shown that CsA increases P-gp expression in proximal tubule and endothelial cells in vitro. The aim of the present study was to investigate the in vivo relevance of these observations in renal allograft biopsies from CsA-treated patients. METHODS: P-gp expression was determined by immunohistochemistry of paraffin sections using two different monoclonal antibodies (UIC2 and MRK16). Biopsies were taken from CsA-treated renal transplant patients with different histopathological diagnoses (N = 79) and were compared with biopsies from normal human kidneys (N = 13) or with allograft biopsies from patients under a CsA-free immunosuppression (N = 15). Moreover, biopsies from 10 donor kidneys before implantation and during rejection episodes ("zero biopsies") were investigated. RESULTS: P-gp expression in biopsies with acute tubular necrosis (ATN; N = 10) after CsA treatment was significantly higher in arterial endothelia, proximal tubules, and epithelial cells of Bowman's capsule (BC), whereas P-gp was sparsely induced in CsA nephrotoxicity (N = 19) compared with controls. Acute cellular (N = 30) and vascular rejection (N = 10) or chronic allograft nephropathy (N = 10) after CsA was associated with strong P-gp expression in infiltrating leukocytes and increased P-gp expression in arterial endothelia, proximal tubules, and BC. In contrast, biopsies of patients treated with a CsA-free immunosuppression regimen did not show increases in P-gp expression compared with controls. Zero biopsies showed a weak, homogeneous, nonpolarized expression of P-gp in tubules and an increased expression of P-gp after CsA therapy in the brush border, arterial endothelia, and BC. CONCLUSIONS: CsA treatment was associated with increased P-gp expression in parenchymal cells of kidney transplants with ATN, acute or chronic transplant rejection, but P-gp was not increased in patients with CsA nephrotoxicity. This indicates that CsA induces its own detoxification by P-gp and that inadequate up-regulation of P-gp in renal parenchymal cells contributes to CsA nephrotoxicity. Increased expression of P-gp in infiltrating leukocytes correlated with the severity of allograft rejection, suggesting that P-gp may decrease the immunosuppressive efficacy of CsA. Thus, individual differences in the P-gp induction response of CsA-exposed renal parenchymal cells and/or infiltrating leukocytes may predispose to either CsA nephrotoxicity or rejection, respectively.

CC chemokine receptor 5 and renal-transplant survival.

BACKGROUND: About 1% of white populations are homozygous carriers of an allele of the gene for the CC chemokine receptor 5 (CCR5) with a 32 bp deletion (CCR5Delta32), which leads to an inactive receptor. During acute and chronic transplant rejection, ligands for CCR5 are upregulated, and the graft is infiltrated by CCR5-positive mononuclear cells. We therefore investigated the influence of CCR5Delta32 on renal-transplant survival. METHODS: Genomic DNA from peripheral-blood leucocytes of 1227 renal-transplant recipients was screened by PCR for the presence of CCR5Delta32. Demographic and clinical data were extracted from hospital records. Complete follow-up data were available for 576 recipients of first renal transplants. Graft survival was analysed by Fisher's exact test and Kaplan-Meier plots compared with a log-rank test. FINDINGS: PCR identified 21 patients homozygous for CCR5Delta32 (frequency 1.7%). One patient died with a functioning graft. Only one of the remaining patients lost transplant function during follow-up (median 7.2 years) compared with 78 of the 555 patients with a homozygous wild-type or heterozygous CCR5Delta32 genotype. Graft survival was significantly longer in the homozygous CCR5Delta32 group than in the control group (log-rank p=0.033; hazard ratio 0.367 [95% CI 0.157-0.859]). INTERPRETATION: Patients homozygous for CCR5Delta32 show longer survival of renal transplants than those with other genotypes, suggesting a pathophysiological role for CCR5 in transplant loss. This receptor may be a useful target for the prevention of transplant loss.