John D. Scandling

Tolerance and Chimerism after Renal and Hematopoietic-Cell Transplantation

We describe a recipient of combined kidney and hematopoietic-cell transplants from an HLA-matched donor. A post-transplantation conditioning regimen of total lymphoid irradiation and antithymocyte globulin allowed engraftment of the donors hematopoietic cells. The patient had persistent mixed chimerism, and the function of the kidney allograft has been normal for more than 28 months since discontinuation of all immunosuppressive drugs. Adverse events requiring hospitalization were limited to a 2-day episode of fever with neutropenia. The patient has had neither rejection episodes nor clinical manifestations of graft-versus-host disease.

Randomized Trial Of Tacrolimus (prograf) In Combination With Azathioprine Or Mychophenolate Mofetil Versus Cyclosporine (neoral) With Mycophenolate Mofetil After Cadaveric Kidney Transplantation1, 2

BACKGROUND Our clinical trial was designed to investigate the optimal combination of immunosuppressants for renal transplantation. METHODS A randomized three-arm, parallel group, open label, prospective study was performed at 15 North American centers to compare three immunosuppressive regimens: tacrolimus + azathioprine (AZA) versus cyclosporine (Neoral) + mycophenolate mofetil (MMF) versus tacrolimus + MMF. All patients were first cadaveric kidney transplants receiving the same maintenance corticosteroid regimen. Only patients with delayed graft function (32%) received antilymphocyte induction. A total of 223 patients were randomized, transplanted, and followed for 1 year. RESULTS There were no significant differences in baseline demography between the three treatment groups. At 1 year the results are as follows: acute rejection 17% (95% confidence interval 9%, 26%) in tacrolimus + AZA; 20% (confidence interval 11%, 29%) in cyclosporine + MMF; and 15% (confidence interval 7%, 24%) in tacrolimus + MMF. The incidence of steroid resistant rejection requiring antilymphocyte therapy was 12% in the tacrolimus + AZA group, 11% in the cyclosporine + MMF group, and 4% in the tacrolimus + MMF group. There were no significant differences in overall patient or graft survival. Tacrolimus-treated patients had a lower incidence of hyperlipidemia through 6 months posttransplant. The incidence of posttransplant diabetes mellitus requiring insulin was 14% in the tacrolimus + AZA group, 7% in the cyclosporine + MMF and 7% in the tacrolimus + MMF groups. CONCLUSIONS All regimens yielded similar acute rejection rates and graft survival, but the tacrolimus + MMF regimen was associated with the lowest rate of steroid resistant rejection requiring antilymphocyte therapy.

Mixed chimerism and immunosuppressive drug withdrawal after HLA-mismatched kidney and hematopoietic progenitor transplantation.

Background. Rodents and dogs conditioned with total-lymphoid irradiation (TLI), with or without antithymocyte globulin (ATG), have been shown to develop mixed chimerism and immune tolerance without graft-versus-host disease (GVHD) after the infusion of major histocompatability complex (MHC)-mismatched donor bone marrow cells given alone or in combination with an organ allograft. Methods. Four human leukocyte antigen (HLA)-mismatched recipients of living donor kidney transplants were conditioned with TLI and ATG posttransplantation and infused with cyropreserved donor granulocyte colony-stimulating factor (G-CSF) “mobilized” hematopoietic progenitor (CD34+) cells (3–5×106 cells/kg) thereafter. Maintenance prednisone and cyclosporine dosages were tapered, and recipients were monitored for chimerism, GVHD, graft function, T-cell subsets in the blood, and antidonor reactivity in the mixed leukocyte reaction (MLR). Results. Three of the four patients achieved multilineage macrochimerism, with up to 16% of donor-type cells among blood mononuclear cells without evidence of GVHD. Prolonged depletion of CD4+ T cells was observed in all four patients. Rejection episodes were not observed in the three macrochimeric recipients, and immunosuppressive drugs were withdrawn in the first patient by 12 months. Prednisone was withdrawn from a second patient at 9 months, and cyclosporine was tapered thereafter. Conclusions. Multilineage macrochimerism can be achieved without GVHD in HLA-mismatched recipients of combined kidney and hematopoietic progenitor transplants. Conditioning of the host with posttransplant TLI and ATG was nonmyeloablative and was not associated with severe infections. Recipients continue to be studied for the development of immune tolerance.

Tolerance and Withdrawal of Immunosuppressive Drugs in Patients Given Kidney and Hematopoietic Cell Transplants

Sixteen patients conditioned with total lymphoid irradiation (TLI) and antithymocyte globulin (ATG) were given kidney transplants and an injection of CD34+ hematopoietic progenitor cells and T cells from HLA‐matched donors in a tolerance induction protocol. Blood cell monitoring included changes in chimerism, balance of T‐cell subsets and responses to donor alloantigens. Fifteen patients developed multilineage chimerism without graft‐versus‐host disease (GVHD), and eight with chimerism for at least 6 months were withdrawn from antirejection medications for 1–3 years (mean, 28 months) without subsequent rejection episodes. Four chimeric patients have just completed or are in the midst of drug withdrawal, and four patients were not withdrawn due to return of underlying disease or rejection episodes. Blood cells from all patients showed early high ratios of CD4+CD25+ regulatory T cells and NKT cells versus conventional naive CD4+ T cells, and those off drugs showed specific unresponsiveness to donor alloantigens. In conclusion, TLI and ATG promoted the development of persistent chimerism and tolerance in a cohort of patients given kidney transplants and hematopoietic donor cell infusions. All 16 patients had excellent graft function at the last observation point with or without maintenance drugs.

Randomized trial of tacrolimus plus mycophenolate mofetil or azathioprine versus cyclosporine oral solution (modified) plus mycophenolate mofetil after cadaveric kidney transplantation: results at 2 years.

Background. A previous report described the 1-year results of a prospective, randomized trial designed to investigate the optimal combination of immunosuppressants in kidney transplantation. Recipients of first cadaveric kidney allografts were treated with tacrolimus+mycophenolate mofetil (MMF), cyclosporine oral solution (modified) (CsA)+MMF, or tacrolimus+azathioprine (AZA). Results at 1 year revealed that optimal efficacy and safety were achieved with a regimen containing tacrolimus+MMF. The present report describes results at 2 years. Methods. Two hundred twenty-three recipients of first cadaveric kidney allografts were randomized to receive tacrolimus+MMF, CsA+MMF, or tacrolimus+AZA. All regimens contained corticosteroids, and antibody induction was used only in patients who experienced delayed graft function. Patients were followed up for 2 years. Results. The results at 2 years corroborate and extend the findings of the previous report. Patients randomized to either treatment arm containing tacrolimus experienced improved kidney function. New-onset insulin dependence remained in four, three, and four patients in the tacrolimus+MMF, CsA+MMF, and tacrolimus+AZA treatment arms, respectively. Furthermore, patients with delayed graft function/acute tubular necrosis who were treated with tacrolimus+MMF experienced a 23% increase in allograft survival compared with patients receiving CsA+MMF (P =0.06). Patients randomized to tacrolimus+MMF received significantly lower doses of MMF compared with those administered CsA+MMF. Conclusions. All three immunosuppressive regi-mens provided excellent safety and efficacy. How-ever, the best results overall were achieved with tacrolimus+MMF. The combination may provide particular benefit to kidney allograft recipients who develop delayed graft function/acute tubular necrosis. Renal function at 2 years was better in the tacrolimus treatment groups compared with the CsA group.

Randomized trial of tacrolimus + mycophenolate mofetil or azathioprine versus cyclosporine + mycophenolate mofetil after cadaveric kidney transplantation : Results at three years

Methods. Two hundred twenty-three recipients of first cadaveric kidney allografts were randomized to receive tacrolimus (TAC) + mycophenolate mofetil (MMF), TAC + azathioprine (AZA), or cyclosporine (Neoral; CsA) + MMF. All regimens contained corticosteroids, and antibody induction was used only in patients who experienced delayed graft function (DGF). Patients were followed-up for 3 years. Results. The results at 3 years corroborate and extend the findings of the 2-year results. Patients with DGF treated with TAC+MMF experienced an increase in 3-year allograft survival compared with patients receiving CsA+MMF (84.1% vs. 49.9%, P =0.02). Patients randomized to either treatment arm containing TAC exhibited numerically superior kidney function when compared with CsA. During the 3 years, new-onset insulin dependence occurred in 6, 3, and 11 patients in the TAC+MMF, CsA+MMF, and TAC+AZA treatment arms, respectively. Furthermore, patients randomized to TAC+MMF received significantly lower doses of MMF as compared with those who received CsA+MMF. Conclusion. All three immunosuppressive regimens provided excellent safety and efficacy. However, the best results overall were achieved with TAC+MMF. The combination may provide particular benefit to kidney allograft recipients with DGF. In patients who experienced DGF, graft survival was better at 3 years in those patients receiving TAC in combination with either MMF or AZA as compared with the patients receiving CsA with MMF.

Late Post-transplant Anemia in Adult Renal Transplant Recipients. An Under-recognized Problem?

Post‐transplant anemia (PTA), a frequent complication during the first 3–6 months after transplant, is thought to be uncommon during the late post‐transplant period. A study population of adults (> 18 years) transplanted during 1995 at Stanford University (n = 88) and University of North Carolina (n = 40) was selected. Data‐collection points were 0, 1, 2, 3, 4 and 5 years post transplant. Anemia was defined as a hematocrit < 33 volume percentage. Thirty percent of patients were anemic at some time during the post‐transplant period. The prevalence of PTA increased over time; by 5 years post transplant, 26% of the patients were anemic. Anemia occurred in 62.5% of patients converted from azathioprine to mycophenolate mofetil. A multivariate logistic regression model demonstrated a correlation between anemia and serum total CO2 (p = 0.002), BUN (p = 0.04), and creatinine (p = 0.045) at 1 year post transplant. At 5 years post transplant, only serum total CO2 (p = 0.0004) correlated with anemia. Thus, diminished renal excretory function and metabolic acidosis appear to be the most important correlates of late PTA. These findings should be interpreted in view of the fact that the newer immunosuppressive agents may have an even more profound effect on anemia and its recovery after transplantation.

Backleak, tight junctions, and cell- cell adhesion in postischemic injury to the renal allograft.

Postischemic injury in recipients of 3-7-d-old renal allografts was classified into sustained (n = 19) or recovering (n = 20) acute renal failure (ARF) according to the prevailing inulin clearance. Recipients of optimally functioning, long-standing allografts and living donors undergoing nephrectomy served as functional (n = 14) and structural controls (n = 10), respectively. Marked elevation above control of fractional clearance of dextrans of graded size was consistent with transtubular backleak of 57% of filtrate (inulin) in sustained ARF. No backleak was detected in recovering ARF. To explore a structural basis for backleak, allograft biopsies were taken intraoperatively, 1 h after reperfusion in all recipients, and again on day 7 after transplant in a subset (n = 10). Electron microscopy revealed disruption of both apical and basolateral membranes of proximal tubule cells in both sustained and recovering ARF, but cell exfoliation and tubule basement membrane denudation were negligible. Histochemical analysis of membrane-associated adhesion complexes confirmed an abnormality of proximal but not distal tubule cells, marked in sustained ARF but not in recovering ARF. Staining for the zonula occludens complex (ZO-1) and adherens complex (alpha, beta, and gamma catenins) revealed diminished intensity and redistribution of each cytoskeletal protein from the apico-lateral membrane boundary. We conclude that impaired integrity of tight junctions and cell-cell adhesion in the proximal tubule provides a paracellular pathway through which filtrate leaks back in sustained allograft ARF.

Mechanisms of filtration failure during postischemic injury of the human kidney. A study of the reperfused renal allograft.

Postischemic filtration failure in experimental animals results primarily from depression of the transcapillary hydraulic pressure difference (delta P), a quantity that cannot be determined in humans. To circumvent this limitation we determined the GFR and each of its remaining determinants in transplanted kidneys. Findings in 12 allografts that exhibited subsequent normofiltration (group 1) were compared with those in 11 allografts that exhibited persistent hypofiltration (group 2). Determinations were made intraoperatively in the exposed graft after 1-3 h of reperfusion. GFR (6 +/- 2 vs 29 +/- 5 ml/min) and renal plasma flow by Doppler flow meter (140 +/- 30 vs 315 +/- 49 ml/min) were significantly lower in group 2 than group 1. Morphometric analysis of glomeruli obtained by biopsy and a structural hydrodynamic model of viscous flow revealed the glomerular ultrafiltration coefficient to be similar, averaging 3.5 +/- 0.6 and 3.1 +/- 0.2 ml/(min.mmHg) in group 2 vs 1, respectively. Corresponding values for plasma oncotic pressure were also similar, averaging 19 +/- 1 vs 21 +/- 1 mmHg. We next used a mathematical model of glomerular ultrafiltration and a sensitivity analysis to calculate the prevailing range for delta P from the foregoing measured quantities. This revealed delta P to vary from only 20-21 mmHg in group 2 vs 34-45 mmHg in group 1 (P < 0.001). Further morphometric analysis revealed the diameters of Bowmans space and tubular lumens, as well as the percentage of tubular cells that were necrotic or devoid of brush border, to be similar in the two groups. We thus conclude (a) that delta P depression is the predominant cause of hypofiltration in this form of postischemic injury; and (b) that afferent vasoconstriction rather than tubular obstruction is the proximate cause of the delta P depression.

Rituximab Failed to Improve Nephrotic Syndrome in Renal Transplant Patients With Recurrent Focal Segmental Glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) recurs in 30% of patients with FSGS receiving a first renal transplant and in over 80% of patients receiving a second transplant after a recurrence. Recurrence often leads to graft failure. The pathogenesis remains unknown and may involve a circulating permeability factor that initiates injury to the glomerular capillary. There are anecdotal reports of pediatric patients with posttransplant lymphoproliferative disorder (PTLD) and recurrent FSGS who have had remission of proteinuria after treatment with rituximab. These observations have prompted speculation that B cells may play a role in the pathogenesis of recurrent FSGS. We report four consecutive adult patients with early recurrent FSGS refractory or dependent on plasmapheresis who received rituximab (total dose 2000–4200 mg). None of the patients treated with rituximab achieved remission in proteinuria, and one patient experienced early graft loss. In these four adult renal transplant patients with recurrent FSGS, rituximab failed to diminish proteinuria.