Relationship Among Viremia/Viral Infection, Alloimmunity, and Nutritional Parameters in the First Year After Pediatric Kidney Transplantation.

The Immune Development in Pediatric Transplantation (IMPACT) study was conducted to evaluate relationships among alloimmunity, protective immunity, immune development, physical parameters, and clinical outcome in children undergoing kidney transplantation. We prospectively evaluated biopsy-proven acute rejection (BPAR), de novo donor-specific antibody (dnDSA) formation, viremia, viral infection, T cell immunophenotyping, and body mass index (BMI)/weight Z scores in the first year posttransplantation in 106 pediatric kidney transplant recipients. Outcomes were excellent with no deaths and 98% graft survival. Rejection and dnDSAs occurred in 24% and 22%, respectively. Pretransplant cytomegalovirus (CMV) and Epstein-Barr virus (EBV) serologies and subsequent viremia were unrelated to BPAR or dnDSA. Viremia occurred in 73% of children (EBV, 34%; CMV, 23%; BMK viremia, 23%; and JC virus, 21%). Memory lymphocyte phenotype at baseline was not predictive of alloimmune complications. Patients who developed viral infection had lower weight (-2.1) (p = 0.028) and BMI (-1.2) (p = 0.048) Z scores at transplantation. The weight difference persisted to 12 months compared with patients without infection (p = 0.038). These data indicate that there is a high prevalence of viral disease after pediatric kidney transplantation, and underweight status at transplantation appears to be a risk factor for subsequent viral infection. The occurrence of viremia/viral infection is not associated with alloimmune events.

Subclinical inflammation and chronic renal allograft injury in a randomized trial on steroid avoidance in pediatric kidney transplantation.

Steroid avoidance is safe and effective in children receiving kidney transplants in terms of graft function and survival, but the effects on allograft histology are unknown. In this multicenter trial, 130 pediatric renal transplant recipients were randomized to steroid-free (SF; n = 60) or steroid-based (SB; n = 70) immunosuppression, and underwent renal allograft biopsies at the time of graft dysfunction and per protocol at implantation and 6, 12 and 24 months after transplantation. Clinical follow-up was 3 years posttransplant. Subclinical acute rejection was present in 10.6% SF versus 11.3% SB biopsies at 6 months (p = 0.91), 0% SF versus 4.3% SB biopsies at 1 year (p = 0.21) and 0% versus 4.8% at 2 years (p = 0.20). Clinical acute rejection was present in 13.3% SF and 11.4% SB patients by 1 year (p = 0.74) and in 16.7% SF and 17.1% SB patients by 3 years (p = 0.94) after transplantation. The cumulative incidence of antibody-mediated rejection was 6.7% in SF and 2.9% in SB by 3 years after transplantation (p = 0.30). There was a significant increase in chronic histological damage over time (p < 0.001), without difference between SF and SB patients. Smaller recipient size and higher donor age were the main risk factors for chronic histological injury in posttransplant biopsies.

Complete steroid avoidance is effective and safe in children with renal transplants: a multicenter randomized trial with three-year follow-up.

To determine whether steroid avoidance in pediatric kidney transplantation is safe and efficacious, a randomized, multicenter trial was performed in 12 pediatric kidney transplant centers. One hundred thirty children receiving primary kidney transplants were randomized to steroid-free (SF) or steroid-based (SB) immunosuppression, with concomitant tacrolimus, mycophenolate and standard dose daclizumab (SB group) or extended dose daclizumab (SF group). Follow-up was 3 years posttransplant. Standardized height Z-score change after 3 years follow-up was -0.99 ± 2.20 in SF versus -0.93 ± 1.11 in SB; p = 0.825. In subgroup analysis, recipients under 5 years of age showed improved linear growth with SF compared to SB treatment (change in standardized height Z-score at 3 years -0.43 ± 1.15 vs. -1.07 ± 1.14; p = 0.019). There were no differences in the rates of biopsy-proven acute rejection at 3 years after transplantation (16.7% in SF vs. 17.1% in SB; p = 0.94). Patient survival was 100% in both arms; graft survival was 95% in the SF and 90% in the SB arms (p = 0.30) at 3 years follow-up. Over the 3 year follow-up period, the SF group showed lower systolic BP (p = 0.017) and lower cholesterol levels (p = 0.034). In conclusion, complete steroid avoidance is safe and effective in unsensitized children receiving primary kidney transplants.

A peripheral blood diagnostic test for acute rejection in renal transplantation.

Monitoring of renal graft status through peripheral blood (PB) rather than invasive biopsy is important as it will lessen the risk of infection and other stresses, while reducing the costs of rejection diagnosis. Blood gene biomarker panels were discovered by microarrays at a single center and subsequently validated and cross-validated by QPCR in the NIH SNSO1 randomized study from 12 US pediatric transplant programs. A total of 367 unique human PB samples, each paired with a graft biopsy for centralized, blinded phenotype classification, were analyzed (115 acute rejection (AR), 180 stable and 72 other causes of graft injury). Of the differentially expressed genes by microarray, Q-PCR analysis of a five gene-set (DUSP1, PBEF1, PSEN1, MAPK9 and NKTR) classified AR with high accuracy. A logistic regression model was built on independent training-set (n = 47) and validated on independent test-set (n = 198)samples, discriminating AR from STA with 91% sensitivity and 94% specificity and AR from all other non-AR phenotypes with 91% sensitivity and 90% specificity. The 5-gene set can diagnose AR potentially avoiding the need for invasive renal biopsy. These data support the conduct of a prospective study to validate the clinical predictive utility of this diagnostic tool.

Pharmacokinetics, pharmacodynamics, safety, and tolerability of single-dose fingolimod (FTY720) in adolescents with stable renal transplants.

Oral fingolimod signals the sphingosine 1-phosphate receptor and this in turn mediates immunomodulatory activity. No data of fingolimod in any pediatric population existed before this study. We put our study results in perspective against data from adult renal transplant patients. We investigated pharmacokinetics and pharmacodynamics of single-dose fingolimod (0.07 mg/kg) and its effects on lymphocytes and heart rate in seven adolescents (14.1 ± 1.6 yr) with stable renal transplants. Blood samples for pharmacokinetics and lymphocytes were collected at screening, baseline, and up to 28 days post-dosing. Cardiac monitoring included 12-lead ECG, 24-h Holter monitoring, and echocardiography. A fingolimod dose of 0.07 mg/kg resulted in mean AUC of 731 ± 240 ng·h/mL and C(max) of 3.6 ± 0.6 ng/mL. Drug exposure was nearly identical to adults receiving the same dose. Absolute lymphocyte count decreased 85% from baseline; average nadir occurred by six h post-dose. Heart rate decreased from 74 bpm (predose mean) to 53 bpm (nadir) three h post-dose. Mean heart rates recovered by Day 14 (75 bpm). Weight-adjusted doses of fingolimod in adolescents resulted in drug exposure similar to adults. Adolescents and adults shared comparable negative chronotropic effects and decreased lymphocyte count. Recovery trajectories of these parameters back to baseline were similar between age groups.

Pharmacokinetics of oral valganciclovir solution and intravenous ganciclovir in pediatric renal and liver transplant recipients.

In an open-label, prospective, pharmacokinetic assessment, we evaluated total drug exposure (area under the curve [AUC]) of intravenous (IV) ganciclovir (GCV) and oral (p.o.) valganciclovir when normalized for body surface area (BSA) in pediatric liver (n=20) and renal (n=26) transplant patients Reference doses for IV GCV (200 mg/m(2)) and p.o. valganciclovir (520 mg/m(2)) were based on adult doses, and adjusted for BSA initially, and BSA and renal function (estimated via creatinine clearance [CrCL]) thereafter. Renal transplant patients received GCV on days 1-2, valganciclovir 260 mg/m(2) on day 3, and valganciclovir 520 mg/m(2) on day 4. Liver transplant patients received twice daily GCV from enrollment to day 12, and then valganciclovir twice daily on days 13-14. GCV pharmacokinetics were described using a population pharmacokinetic approach. Type of solid organ transplant (kidney or liver) had no effect on GCV pharmacokinetics. Median GCV exposure following valganciclovir 520 mg/m(2) was similar to that with IV GCV, and to that reported in adults. Patients <5 years of age had AUC values approximately 50% of those compared with older age ranges; dosing based on both BSA and CrCL increased drug exposure in younger patients. A dosing algorithm based on BSA and CrCL should be tested in future studies.

Valganciclovir dosing according to body surface area and renal function in pediatric solid organ transplant recipients.

Oral valganciclovir is effective prophylaxis for cytomegalovirus (CMV) disease in adults receiving solid organ transplantation (SOT). However, data in pediatrics are limited. This study evaluated the pharmacokinetics and safety of valganciclovir oral solution or tablets in 63 pediatric SOT recipients at risk of CMV disease, including 17 recipients < or =2 years old. Patients received up to 100 days' valganciclovir prophylaxis; dosage was calculated using the algorithm: dose (mg) = 7 x body surface area x creatinine clearance (Schwartz method; CrCLS). Ganciclovir pharmacokinetics were described using a population pharmacokinetic approach. Safety endpoints were measured up to week 26. Mean estimated ganciclovir exposures showed no clear relationship to either body size or renal function, indicating that the dosing algorithm adequately accounted for both these variables. Mean ganciclovir exposures, across age groups and organ recipient groups were: kidney 51.8 +/- 11.9 microg * h/mL; liver 61.7 +/- 29.5 microg * h/mL; heart 58.0 +/- 21.8 microg * h/mL. Treatment was well tolerated, with a safety profile similar to that in adults. Seven serious treatment-related adverse events (AEs) occurred in five patients. Two patients had CMV viremia during treatment but none experienced CMV disease. In conclusion, a valganciclovir-dosing algorithm that adjusted for body surface area and renal function provides ganciclovir exposures similar to those established as safe and effective in adults.

Nonadherence consensus conference summary report.

This report is a summary of a 'Consensus Conference' on nonadherence (NA) to immunosuppressants. Its aims were: (1) to discuss the state-of-the-art on the definition, prevalence and measurement of NA, its risk factors and impact on clinical and economical outcomes and interventions and (2) to provide recommendations for future studies. A two-day meeting was held in Florida in January 2008, inviting 66 medical and allied health adherence transplant and nontransplant experts. A scientific committee prepared the meeting. Consensus was reached using plenary and interactive presentations and discussions in small break-out groups. Plenary presenters prepared a summary beforehand. Break-out group leaders initiated discussion between the group members prior to the meeting using conference calls and e-mail and provided a summary afterward. Conclusions were that NA: (a) is more prevalent than we assume; (b) is hard to measure accurately; (c) tends to confer worse outcomes; (d) happens for a number of reasons, and system-related factors including the patient's culture, the healthcare provider and the setting and (e) it is not currently known how to improve adherence. This consensus report provided some roadmaps for future studies on this complicated, multifaceted problem.

Should pediatric patients wait for HLA-DR-matched renal transplants?

Graft survival rates from deceased donors aged 35 years or less among all primary pediatric kidney transplant recipients in the United States between 1996 and 2004 were retrospectively examined to determine the effect of HLA-DR mismatches on graft survival. Zero HLA-DR-mismatched kidneys had statistically comparable 5-year graft survival (71%), to 1-DR-mismatched kidneys (69%) and 2-DR-mismatched kidneys (71%). When compared to donors less than 35 years of age, the relative rate of allograft failure was 1.32 (p = 0.0326) for donor age greater than or equal to age 35. There was no statistical increase in the odds of developing a panel-reactive antibody (PRA) greater than 30% at the time of second waitlisting, based upon the degree of HLA-A, -B or -DR mismatch of the first transplant, nor was there a 'dose effect' when more HLA antigens were mismatched between the donor and recipient. Therefore, pediatric transplant programs should utilize the recently implemented Organ Procurement and Transplantation Network's (OPTN)allocation policy, which prioritizes pediatric recipients to receive kidneys from deceased donors less than 35 years of age, and should not turn down such kidney offers to wait for a better HLA-DR-matched kidney.

Somatomedin activity and inorganic sulfate in children undergoing hemodialysis.

Bioassayable serum somatomedin activity could be estimated in uremic subjects only after appropriate correction for increased circulating inorganic sulfate. Somatomedin activity increased after hemodialysis in six of ten patients, possibly due to removal of somatomedin inhibitors.

Cadaver renal transplantation in children with cystinosis.

Five children with end-stage renal disease resulting from cystinosis received seven cadaver renal allografts. Four recipients have functioning grafts eight to 55 months after receiving the transplant and one recipient lost two grafts at 17 and 26 months after the transplant. There was no florid recurrence of the Fanconi syndrome although proximal renal tubular dysfunction developed in two patients, in one in association with chronic rejection and in one without apparent etiology. Free cystine content of white blood cells, cultured skin fibroblasts and allograft tissue was significantly increased. Cystine crystals were observed in the mesangium of two grafts and in the interstitial tissue of all grafts; however, no cystine crystals were found in the tubules. The location of the cystine crystals, as well as the fact that the highest free level of cystine of allograft tissue was observed in the graft undergoing chronic rejection. led to the hypothesis that recipient cells infiltrating the graft were the source of cystine deposition. The data indicate that successful cadaveric transplantation does not correct the primary metabolic defect in cystinosis, thereby explaining the persistence of the extrarenal clinical manifestations, such as photophobia and hypothyroidism, after renal transplantation in cystinosis.

Autolymphocytotoxic antibodies in patients on dialysis awaiting renal transplantation.

Two-hundred eighty sera from 78 dialysis patients were examined for autolymphocytotoxic antibodies (ALCAs). Thirty-five (12%) sera in 18 (23%) patients had ALCAs. Eight patients had ALCAs in multiple sera. Two patients had ALCAs against both T and B lymphocytes, 2 against T lymphocytes, and 14 against B lymphocytes. In those sera with ALCAs against both B and T lymphocytes, broad thermal reactivity was present. In sera with ALCAs against only B lymphocytes, the majority were reactive at 5 C. Sixteen (89%) patients with ALCAs had some form of glomerulonephritis; five had rapidly progressive glomerulonephritis (RPGN) and three had systemic lupus erythematosis (SLE). Nine of 10 sera with a positive crossmatch against B lymphocytes from a renal transplant donor did not have ALCAs against autologous B lymphocytes; three sera with ALCAs against B lymphocytes and two with ALCAs against T lymphocytes had negative crossmatches against transplant donor lymphocytes. Positive crossmatches against donor B and T lymphocytes attributable solely to ALCAs were therefore uncommon in our patients. Nevertheless, patients at risk to develop ALCA, including those with SLE and RPGN, should be identified and their sera tested for ALCAs. Once identified, studies can be carried out to distinguish a positive crossmatch attributable to ALCAs from that attributable to HLA alloantibody.

Cadaver renal transplant outcome in recipients with autolymphocytotoxic antibodies.

The major impact of autolymphocytotoxic antibodies (ALCA) on renal transplantation has been in the interpretation of the pretransplant crossmatch as a cause of false-positive results. Less attention has been paid to the direct affects of ALCA on renal allografts. We have examined the sera of 38 recipients of 41 cadaver renal allografts for the presence of ALCA. There were 9 patients with ALCA who received 10 allografts. In these allografts with ALCA, actuarial graft survival was significantly improved (P less than 0.05) over that of 31 transplants without ALCA. In recipients with ALCA, graft survival was 90% at six months and 60% at one and two years; in recipients without ALCA, graft survival was 48% at six months, 35% at one year and 24% at two years. ALCA may be exerting graft-enhancing properties by means of an autoregulatory effect upon the recipient's immunologic system.

Serial decrease in glomerular filtration rate in long-term pediatric liver transplantation survivors treated with cyclosporine.

Serial calculations of glomerular filtration rate were made in 31 pediatric liver transplant recipients surviving more than 1 year. GFR was computed from the Schwartz formula, (cGFR = KL/S Cr), before orthotopic liver transplantation, and at 3-6 monthly intervals thereafter. At the same time points, CsA dose/kg, CsA level, blood pressure, and liver functions were recorded. The mean difference between the pre-OLT cGFR and the most-current cGFR for all patients was -50 ml/min/1.73 m2 (P = less than 0.005). In 17/31 (55%), the current cGFR was less than 80 ml/min/1.73 m2, indicative of renal impairment. The cGFR continued to decrease in 24 patients followed beyond 1 year (26.8 ml/min/1.73 m2 per year decrease, P less than 0.005). More patients with a cGFR less than 80 ml/min/1.73 m2 had outpatient hypertension. There was no correlation of cGFR with CsA levels, CsA dose, or liver function. We conclude that a significant decrease in cGFR is seen in children treated with CsA for more than 1 year, which is progressive in the majority.

Long-term cadaver allograft survival in the recipient with a positive B lymphocyte crossmatch.

Over a 2 1/2-year period, prospective standard, T, and B lymphocyte crossmatches were performed in 45 cadaver renal transplants using the microlymphocytotoxicity technique. Twenty-three of the 45 recipients had a positive B lymphocyte crossmatch. Cumulative graft survival rates did not differ between recipients with a positive and negative B lymphocyte crossmatch. High levels of presensitization in routine lymphocytotoxic antibody screening or transplant number did not adversely affect graft survival in recipients with a positive B lymphocyte crossmatch. Five recipients had moderately positive standard crossmatches which were attributable to anti-B lymphocytotoxicity. Four of these five grafts are presently functioning with normal serum creatinine levels 9 to 14 months post-transplant. A positive B lymphocyte crossmatch is compatible with good long-term cadaveric renal allograft survival. In addition, a weakly positive standard crossmatch is not a contraindication to transplantation when the positive crossmatch is attributable to anti-B lymphocyte antibody.

The effect of hypoprolactinemia alone and in combination with cyclosporine on allograft rejection.

Recent evidence suggests that prolactin has a role in regulating immune function. Hypophysectomy or administration of bromocriptine results in suppression of the immune response, which is reversed by the administration of prolactin. Hypoprolactinemia has been shown to augment the immunosuppressive effect of cyclosporine. We studied the effect of hypoprolactinemia induced by a new drug, CQP 201-403, on the survival of heterotopic cardiac allografts in the rat and the ability of peripheral blood lymphocytes to respond in vitro to plant mitogens. CQP treatment alone produced a small increase in graft survival but no change in lymphocyte in vitro proliferation (P less than 0.05). CQP treatment greatly enhanced the immunosuppressive effect of cyclosporine on graft rejection and in vitro lymphocyte function (P less than 0.02). We conclude that modulation of prolactin may be a useful adjunct to cyclosporine immunosuppression.

Acute renal allograft rejection. Comparative value of ultrasound versus magnetic resonance imaging.

Both magnetic resonance imaging (MRI) and ultrasound (US) have been reported to be useful in differentiating between acute allograft rejection and other causes of graft dysfunction in renal transplantation. The aim of this study was to evaluate the comparative usefulness of these techniques in the assessment of patients with acutely rising serum creatinine levels. Seventeen patients with 19 episodes of acute serum creatinine elevations were evaluated for the presence of acute rejection. The ultimate diagnoses of acute rejection were based on either renal pathological findings, or the response to standard antirejection therapy. Clinical, US and MRI diagnoses were assessed independently, without knowledge of the results of the other evaluation techniques. We found that US alone was useful in diagnosing acute rejection (x2 = 4.95, P less than 0.05), and when taken in the clinical setting was an added advantage (x2 = 6.68, P less than 0.01). MRI did not increase the diagnostic accuracy significantly.

Determination of antiidiotypic antibodies to anti-HLA IgG following blood transfusions.

Blood transfusions (BT) administered prior to renal allograft transplantation are known to enhance allograft survival. One proposed mechanism for this effect is through the induction of antiidiotypic antibodies that modify the immune response to subsequently presented graft antigens. In an attempt to determine if antiidiotypic antibodies are generated post-BT, we studied sera from post-BT patients for the presence of antiidiotypic antibodies to anti-HLA class I IgG (i.e., anti-anti-HLA). Anti-HLA antiidiotypes were demonstrated by idiotype-specific inhibition of an enzyme immunoassay (EIA) for anti-HLA antibodies. Using this inhibition technique, test sera from 8 of 16 post-BT patients showed significant inhibition of the anti-HLA target sera (P less than 0.05). Sera from normal individuals showed no inhibition of the target sera, and test sera did not inhibit other antigen-antibody systems. Protein A absorption of test sera eliminated the inhibitory effect, suggesting that the antiidiotypic activity was limited to the IgG fraction of the sera. The EIA binding activity of F(ab')2 fragments of anti-HLA IgG was suppressed by sera from patients post-BT but not by sera from normal volunteers. Studies of serially obtained sera from a post-BT patient showed that anti-HLA antiidiotype levels fluctuate with time and transfusion status. These studies demonstrate that anti-HLA antiidiotypic antibodies are generated post-BT. Their importance in mediating the known allograft-enhancing effect of pretransplant BT remains to be clarified.

Plasma exchange for recurrent nephrotic syndrome following renal transplantation.

Patients with steroid-resistant nephrotic syndrome and focal segmental glomerulosclerosis (FGS) who develop end-stage renal disease are at risk for recurrence of the disease following renal transplantation. Recurrence of the nephrotic syndrome in renal allografts of two children with primary FGS was successfully controlled by plasma exchange. This report suggests that plasma exchange instituted early in the course of recurrent nephrotic syndrome may be beneficial in some patients with steroid-resistant nephrotic syndrome and FGS.

Circulating immune complexes in pediatric renal allograft rejection.

Previous reports on the generation and nephritogenic capacity of post-transplant circulating immune complexes (CICs) are conflicting. To assess the pathogenicity of CICs in acute rejection (AR), 784 CIC determinations were performed on 392 serum samples from 27 pediatric renal allograft recipients using the C1q-solid phase assay (C1q-SPA) and the Raji cell radioimmunoassay (Raji-RIA). Serum samples from transplant recipients not undergoing rejection episodes and from normal subjects served as controls. Of the 784 CIC determinations, 723 (92.3%) were negative in both assays. CICs were present at some point post-transplant in eight (19.6%) recipients. Correlation of CIC levels with allograft rejection was found in only two patients with CIC levels responding to antirejection therapy; however, statistical analysis of data by chi 2 analysis failed to reveal a significant correlation of CICs with AR episodes. Allograft histology in three recipients demonstrated characteristic signs of AR. Immunofluorescent studies did not reveal significant deposition of immunoglobulin or complement. Sucrose density gradient ultracentrifugation studies confirmed the immune complex nature of materials reactive with the CIC assays. There was no immunological evidence supporting antithymocyte globulin (ATG) as an immunogen in patients demonstrating CICs post-transplant. CICs do not appear to be an important mediator of AR. Statistical analysis of data using the chi 2 test failed to reveal a positive correlation of CIC levels with AR or ultimate allograft outcome.