Gérard Rifle

Detection of donor-specific anti-HLA antibodies with flow cytometry in eluates and sera from renal transplant recipients with chronic allograft nephropathy.

Background. Chronic allograft nephropathy (CAN), which remains the main cause of graft loss after kidney transplantation, is still poorly understood. Because anti-HLA antibodies may be involved in the pathogenesis of CAN, this study was performed to look for donor-specific antibodies (DSA) fixed onto renal transplants with CAN. Methods. DSA were identified after elution with flow cytometric assay and/or flow cytometric crossmatches in 20 transplants removed after irreversible graft failure caused by CAN and in control samples from 2 transplants with relapsing glomerulopathy, 2 transplants lost after vascular thrombosis, and 4 normal kidneys. The results were compared with those obtained in the serum samples 1 year after grafting, at the time of transplantectomy, and within 2 months after transplantectomy. Results. IgG anti-class I, anti-class II, or both DSA were identified in 70.6% of eluates versus 73.6% of posttransplantectomy serum samples (NS), 42.1% of 1-year postgrafting serum samples (P <0.05), and 31.6% of serum samples at the time of transplantectomy (P <0.05). Our data show a good correlation between the target of anti-HLA antibodies found in both eluates and posttransplantectomy serum samples, but the precise specificity of anti-HLA antibodies is more often assigned in posttransplantectomy serum samples than in eluates. This problem needs further evaluation. Conclusion. This study shows that testing for anti-HLA DSA in eluates from removed kidney transplants using flow cytometry can be achieved and is highly efficient. It already suggests that both anti-class I and anti-class II HLA antibodies can be involved in CAN. Further studies are now needed to evaluate the possibility of identifying such antibodies in the eluates of transplant biopsy specimens from recipients experiencing CAN.

A three-arm study comparing immediate tacrolimus therapy with antithymocyte globulin induction therapy followed by tacrolimus or cyclosporine A in adult renal transplant recipients.

Background. Induction therapy with antithymocyte globulin (ATG) reduces the incidence of acute rejection after transplantation. A study was undertaken to assess the efficacy and safety of ATG induction on tacrolimus-based and cyclosporine A (CsA)-based therapies compared with immediate tacrolimus triple therapy in kidney transplant recipients. Methods. In a 6-month, open-label, randomized, prospective study conducted in 30 European centers, 555 renal transplant patients were randomly assigned to tacrolimus triple therapy (Tac triple, n=185), ATG induction with tacrolimus (ATG-Tac, n=186), or ATG induction with CsA microemulsion (ATG-CsA, n=184); all were combined with azathioprine and corticosteroids. The primary endpoint was incidence and time to first acute rejection episode confirmed by biopsy. Results. Patient demographics and clinical parameters at baseline were similar. Patient and graft survival rates were similar in all groups. The incidence of clinically apparent acute rejection was significantly higher (P =0.003) for Tac triple (33.0%) compared with ATG-Tac (22.6%) and the incidence for ATG-Tac was significantly lower (P =0.004) than for ATG-CsA (37.0%). The incidences of acute rejection confirmed by biopsy (primary endpoint) were 25.4%, 15.1%, and 21.2% for Tac triple, ATG-Tac, and ATG-CsA, respectively (Tac triple vs. ATG-Tac, P =0.004). The incidences of corticosteroid-resistant acute rejection were 7.0% (Tac triple), 4.8% (ATG-Tac), and 10.9% (ATG-CsA) (ATG-Tac vs. ATG-CsA, P =0.038). In the ATG groups, the incidences of leukopenia, thrombocytopenia, serum sickness, fever, and cytomegalovirus infection were significantly higher (P <0.05). Conclusions. Acute rejection was significantly lower in the ATG-Tac group compared with the ATG-CsA and Tac triple groups. Significantly more hematologic and infectious adverse events were observed in both ATG induction groups.

Donor-specific antibodies in allograft rejection: clinical and experimental data.

The ability of donor-specific major histocompatibility complex alloantibodies to destroy a transplanted organ within minutes, the so-called hyperacute rejection phenomenon, has been known for a long time. It is a clear demonstration of the possible cytotoxic effect of antibodies. Apart from this particular situation, the role of antibodies in inducing acute or chronic allograft rejection remains controversial. Many clinical data have shown that transplant recipients capable of developing class I or class II anti-HLA antibodies experienced shorter survival periods than those who were not. This fact, in accordance with experimental data, only demonstrates that high antibody responders reject a transplant more easily than low responders. More interestingly, there is now increasing evidence that posttransplant appearance of donor-specific alloantibodies, and probably of alloreactive-induced autoantibodies, is strongly correlated with reduced graft survival rate, especially from chronic rejection. We demonstrated that donor-specific HLA antibodies can be found in more than 70% of transplanted kidneys with chronic allograft nephropathy, and that the intragraft presence of such antibodies is significantly correlated with high numbers of plasma cells on early biopsies and C4d deposits, a recognized marker of humoral rejection. It is likely that non-HLA antibodies also play a deleterious role in organ transplant outcome, particularly the heterogeneous group of anti-endothelial cells antibodies, anti-MIC antibodies, autoantibodies and some others with no recognized target. Convincing experimental data, especially using B cell and T cell deficient mice, strongly suggest that B cells and donor-specific antibodies are required for fully developed chronic allograft rejection. The role of antibodies in inducing the cascade of cytokines and growth factors leading to tissue lesions is of increasing interest since it is now possible to control B cell proliferation and antibody production.

Thymoglobulin induction and sirolimus versus tacrolimus in kidney transplant recipients receiving mycophenolate mofetil and steroids.

Background. To define the role of mammalian target of rapamycin inhibitors in kidney transplantation, we compared efficacy and safety of two immunosuppressive regimens—a calcineurin inhibitor-free regimen with depletive induction versus a calcineurin inhibitor-based regimen. Methods. De novo renal allograft recipients were randomized before transplantation to receive sirolimus (SRL; n=71, group A) or tacrolimus (n=70, group B). All patients received mycophenolate mofetil and corticosteroids. In group A, patients received rabbit antithymocyte globulin induction. In group B, antithymocyte globulin therapy could be given in case of delayed graft function. The estimated glomerular filtration rate (GFR) (Nankivells formula) at month 12 was the primary endpoint. Results. GFR showed no significant difference at month 12, with 56.1 in group A versus 58.4 mL/min/1.73 m2 in group B. In functioning grafts, renal function was significantly better in the SRL group, with higher GFR values at months 1, 2, 3, 6, and 9 (P<0.05). At month 12, patient survival and incidence of biopsy-proven rejection were not different between groups (95.8% vs. 97.1%, and 16.9% vs. 12.9%, respectively). However, proportion of graft loss was higher with SRL at months 6 and 12 (11.3% vs. 0.0%, P=0.004; 14.1% vs. 4.3%, P=0.044, respectively). Adverse events and premature withdrawals were more frequent with SRL (P<0.001 and P<0.05, respectively), whereas cytomegalovirus infections were more frequent with tacrolimus (P<0.001). Conclusion. Patients treated with induction plus SRL, mycophenolate mofetil, and corticosteroids may obtain good renal function but have a higher risk of adverse events, drug withdrawal, and graft loss.

Influence of islet transportation on pancreatic islet allotransplantation in type 1 diabetic patients within the Swiss-French GRAGIL network

Background. The influence of islet transportation on pancreatic islet allotransplantation in type 1 diabetic patients was evaluated within the GRAGIL network. Patients and Methods. From December 2001 to April 2003, 16 human pancreatic islet transplants were performed in 9 type 1 diabetic patients with an established kidney graft (functioning for at least 6 months) in four centers of the GRAGIL network. Islet isolation was performed in a core laboratory in Geneva, and the islet preparations were shipped by ambulance to each center for transplantation. One month after transplantation, the efficiency of the graft was assessed according to islet transportation time (ITT): ITT less than 2 hours (group 1, n=5), and ITT greater than 4.5 hours (group 2, n=4, mediant 5 hours). Results. Primary graft dysfunction was observed in one patient in group 1 after one month. Two patients became insulin independent in groups 1 and 2. All other patients in both groups had a plasma C-peptide level greater than 0.5 ng/ml. The HbA1c level and the exogenous insulin needs decreased in both groups. Conclusions. ITT does not seem to influence the efficiency of pancreatic islet allotransplantation in type 1 diabetic patients. These results emphasize the scope for multicenter networks such as the GRAGIL group.

Donor-derived hematopoietic cells in organ transplantation: a major step toward allograft tolerance?

Infusion of donor-derived cells can improve organ allograft survival in animal models. Under certain conditions, it can even induce tolerance (i.e., unlimited organ survival without any maintenance immunosuppressive therapy). Use of nonmyeloablative regimens allows engraftment of donor-derived bone marrow cells, induction of mixed chimerism, and tolerance in rodents. High doses of bone marrow cells together with anti–T-cell antibodies can even result in mixed chimerism without cytoablative host conditioning. Cultured donor-derived CD34+ cells or donor-derived immature (or even mature) dendritic cells associated with monoclonal antibodies directed against co-stimulatory molecules might also induce tolerance. Among the numerous experimental protocols leading to tolerance of solid organs in animal models, how can we find our bearings in human transplantation? Numerous problems have yet to be solved: the type and amount of donor-derived cells (including stromal cells) to be used, the timing for infusion of donor cells in keeping with organ transplantation, the route of infusion (should it be intravenous, into the portal vein?), and the conditioning regimen. The first clinical trials would appear to indicate that tolerance induction in humans using donor-derived cells is a relatively safe solution that is both promising and realistic.

Successful Hepatorenal Transplantation in Hereditary Amyloidosis Caused by a Frame‐Shift Mutation in Fibrinogen Aα‐Chain Gene

Hereditary systemic amyloidosis comprises several autosomal dominant diseases caused by mutations in a number of plasma proteins, including the fibrinogen Aα‐chain. Four mutations in the fibrinogen Aα‐chain that are able to induce amyloidosis have been identified so far, the most common being the Glu526Val mutation. We have observed a family in which the father and his son reached end‐stage renal failure because of renal amyloidosis induced by a frame‐shift mutation in the fibrinogen Aα‐chain gene producing a novel amyloid protein. Two kidney transplantations in the father and one in the son resulted in fast graft loss caused by recurrence of amyloid deposition. We then performed hepatorenal transplantation in the son. Three years later, liver and kidney functions are normal without recurrence of amyloid deposition. This case, together with three others with the Glu526Val mutation in the extensive literature, suggests that liver transplantation can cure hereditary fibrinogen amyloidosis, whatever the mutation may be.

Foscarnet-induced crystalline glomerulonephritis with nephrotic syndrome and acute renal failure after kidney transplantation.

Foscarnet nephrotoxicity has been reported to be associated with acute tubulointerstitial nephritis. Crystals in glomerular capillary lumens have also been observed in patients with acquired immunodeficiency syndrome who were treated with foscarnet for cytomegalovirus disease. We describe a kidney transplant recipient who developed a nephrotic syndrome with microscopic hematuria and nonoliguric acute renal failure within 15 days after starting foscarnet therapy for cytomegalovirus infection. A kidney biopsy specimen showed the presence of crystals in all glomeruli and in proximal tubules. Fourier transform infrared microscopy analysis demonstrated that crystals were made from several forms of foscarnet salts: mixed calcium and sodium salts, and unchanged trisodium foscarnet salts. Renal function and proteinuria spontaneously improved, and a second transplant biopsy performed 8 months after the first one revealed fibrotic organization of half of the glomeruli and of interstitial tissue, and crystal vanishing. We were thus able to provide proof of the possible precipitation of foscarnet in a transplanted kidney.

Detection of plasma cells, C4d deposits and donor-specific antibodies on sequential graft biopsies of renal transplant recipients with chronic dysfunction

BACKGROUND In order to look for a relationship between humoral mechanisms of rejection and chronic allograft dysfunction, plasma cells, C4d deposits and donor-specific antibodies (DSA) were simultaneously sought on serial biopsies of kidney allograft recipients. PATIENTS AND METHODS Ten recipients with chronic dysfunction (G1) and 8 recipients with long-term normal graft function (G2) were included. Biopsies and serums were sampled at early graft dysfunction (T1), between 8months and 2years (T2) and after the third year following transplantation (T3). RESULTS In G1, plasma cells represented 12.3% (T1), 8.2% (T2) and 14.1% (T3) of mononuclear cells. The mean percentage of plasma cells was 11.6% in G1 versus 0.4% in G2 (p<0.05). A progressive rise in C4d deposits was seen in G1, from 25% at T1 to 80% at T3. Donor-specific antibodies were identified in at least one serum sample of 60% of the patients in G1 and 12.5% of the patients in G2 (p=0.012), whereas donor-specific antibodies were eluted from at least one biopsy of 50% of the patients in G1 and 12.5% of the patients in G2 (p=0.03). In G1, C4d deposits were significantly associated with plasma cells (p=0.0012) and anti-HLA Abs in serum samples and/or eluates (p=0.026). CONCLUSION This study shows that plasma cells, DSA and C4d are associated in renal transplants developing chronic rejection.

Influence of ischemia on heart-rate variability in chronic hemodialysis Patients

Background: Sudden cardiac death occurring in patients with end-stage renal disease (ESRD) may be related to poor autonomic function with a significant decreased heart-rate variability (HRV). In addition, coronary artery disease has a high prevalence in this population and accounts for 50% of deaths. In the present study, relationships between HRV and myocardial ischemic abnormalities revealed by myocardial scintigraphy (MS) were evaluated in 32 chronic hemodialysis patients. Methods: We prospectively studied 32 chronic hemodialysis patients. Each underwent MS and 24 h electrocardiography at baseline for analysis of time and frequency domain the day of dialysis. Three periods were analyzed: during dialysis session, the morning after (nondialytic period), and in a 24 h period. Patients were included in group 1 (seven women, 11 men; mean age: 62 ± 19 years) when MS revealed no ischemia, whereas patients were included in group 2 (seven women, seven men; mean age: 63.1 ± 20 years) when MS revealed ischemic lesions. Results: A student ± test revealed that during the nondialytic period, two important markers of HRV, percentage of delta RR > 50 ms (pNN50) (4.5 ± 4.04 in group 1 versus 1.7 ± 1.4 in group 2), and root mean square of delta RR (rMSSD) (27.7 ± 13.4 versus 19.7 ± 6.8) were significantly reduced in group 2 compared with values in group 1. No significant difference appears between the two groups for standard deviation of normal to normal intervals (SDNN), mean heart rate, and spectral analysis. Conclusion: Patients with ESRD and myocardial ischemia revealed by MS have reduced parasympathetic activity during the nondialytic period. Correlations between parameters of HRV and ischemic lesions revealed by MS have been shown for the first time.