Specific immune biomarker monitoring in two children with severe IgA nephropathy and successful therapy with immunoadsorption in a rapidly progressive case.

BACKGROUND: Childhood IgA nephropathy (cIgAN) is one of the most common primary glomerulonephritides with the potential to evolve to kidney failure. IgAN is an autoimmune disease involving 3 key factors: galactose-deficient IgA1 (Gd-IgA1), anti-IgA1 autoantibodies, and soluble (s)CD89 IgA Fc receptor. These molecules and immune complexes have been described recently as potential biomarkers of disease progression in childhood IgAN but their evolution in time under immunosuppressive treatment remains unknown. METHODS: We performed a prospective study of two proliferative cIgAN patients by sequentially biomonitoring immune IgA complexes (sCD89-IgA, IgG-IgA), sCD89, and Gd-IgA1 and correlating them with clinical and histological outcome after treatment. RESULTS: After patient 1's treatment, a decrease in sCD89-IgA, IgG-IgA, and free sCD89 was linked to a decrease in proteinuria whereas eGFR (estimated glomerular filtration rate) and Gd-IgA1 levels remained stable. Patient 1 received tacrolimus and monthly intramuscular steroid injections of Kenacort for 10 months. At the end, a relapse induced an increase in proteinuria consistent with an increase of the 3 biomarkers. Patient 2 displayed rapidly progressive IgAN with crescents in more than 90% of glomeruli and received intense immunosuppression treatment associated with the immunoadsorption (IA) approach. During IA, proteinuria decreased rapidly, as well as levels of CD89-IgA, IgG-IgA, sCD89, and Gd-IgA1 biomarkers. After discontinuation of IA, proteinuria increased as well as IgG-IgA complexes whereas sCD89-IgA and sCD89 remained low. Further re-intensification of IA and addition of cyclophosphamide improved proteinuria again with reduced IgG-IgA. A second biopsy was performed showing a reduction of extracapillary proliferation to 6% of glomeruli and only 9% glomerulsoclerosis. CONCLUSIONS: In conclusion, sequential biomonitoring of Gd-IgA1, IgA-immune complexes, and sCD89 in cIgAN was found to be valuable, by correlating with clinical features and glomerular proliferative lesions in cIgAN. These biomarkers could represent useful tools to evaluate kidney injury without repeat kidney biopsies.

Anti-rituximab antibodies in pediatric steroid-dependent nephrotic syndrome.

BACKGROUND: Rituximab is a chimeric anti-CD20 monoclonal antibody that induces sustained remission in children with steroid-dependent nephrotic syndrome. However, there is no consensus on the optimal regimen and monitoring of rituximab. In other autoimmune diseases, anti-rituximab antibodies (ARA) have been reported in 10-40% of patients, but their clinical relevance remains unclear. In nephrotic syndrome, data are scarce. METHODS: We report a single-center retrospective study with immuno- and pharmacological monitoring of rituximab treatment in children with frequent relapsing (FR) or steroid-dependent nephrotic syndrome (SDNS). We analyzed the monthly monitoring of 24 children, receiving a dose of rituximab (375 mg/m2) between December 2017 and April 2018 at the Pediatric Nephrology Department of Robert-Debré hospital, Paris. RESULTS: ARA were detected in 7/24 patients (29%), sometimes after the first infusion of rituximab. ARA were present at baseline in two patients previously treated with rituximab. Both displayed no B-cell depletion. ARA were also reported in 5/22 patients during follow-up, with antibodies always detected in the first month following B-cell recovery. An incomplete CD19+CD20- B-cell depletion at M1 (5-25/mm3) and low serum rituximab levels was predictive of developing ARA. The development of de novo ARA during follow-up was not associated with shorter B-cell depletion. CONCLUSIONS: This study shows that ARA are frequent in children with FR/SDNS and that close immuno- and pharmacological monitoring may help personalizing rituximab treatment in patients needing repeated injections.

A global antiB cell strategy combining obinutuzumab and daratumumab in severe pediatric nephrotic syndrome.

BACKGROUND: Steroid-sensitive nephrotic syndrome (SSNS) is, in most patients, a chronic disease with 80% experiencing at least one relapse after first flare. B cell depletion using rituximab is effective in preventing relapse in steroid-dependent (SDNS) patients but fails to maintain long-term remission following B cell recovery, possibly due to development of autoreactive long-lived plasma cells. We investigated sequential combination of antiCD20 antibody targeting all B cell subsets, and antiCD38 antibody with high plasma cell cytotoxicity in patients with uncontrolled SDNS after failure of one or several attempts at B cell depletion. METHODS: Fourteen patients with median disease duration 7.8 years received 1000 mg/1.73 m2 obinutuzumab followed by 1000 mg/1.73 m2 daratumumab 2 weeks later. Oral immunosuppression was discontinued within 6 weeks, and biological monitoring performed monthly until B cell recovery. RESULTS: Median age at treatment was 11.0 [IQR 10.4-14.4] years. B cell depletion was achieved in all patients, and B cell reconstitution occurred in all at median 9.5 months after obinutuzumab injection. After median follow-up 20.3 months (IQR 11.5-22.6), 5/14 patients relapsed including 4 within 100 days following B cell repletion. Relapse-free survival was 60% at 24 months from obinutuzumab infusion. Mild infusion reactions were reported in 3/14 patients during obinutuzumab and 4/14 during daratumumab infusions. Mild transient neutropenia (500-1000/mm3) occurred in 2/14 patients. Intravenous immunoglobulins were given to 12/14 patients due to hypogammaglobulinemia. Low IgA and IgM levels were noted in 8 and 14 patients, respectively. No severe infection was reported. CONCLUSION: Global antiB cell strategy combining obinutuzumab and daratumumab induces prolonged peripheral B cell depletion and remission in children with difficult-to-treat SDNS.

A Successful Renal Transplant in a Pediatric Patient With Glanzmann Thrombasthenia and Hyperimmunization.

We report the case of a patient with type 2 Glanzmann thrombasthenia who underwent successful kidney transplant with his mother's kidney. He started dialysis at 13 months. The patient had been diagnosed with Glanzmann thrombasthenia at 9 years old, after hemorrhagic shock, during which multiple transfusions were required and hyperimmunization had developed. At 12 years old, he received a kidney transplant. Before transplant, ABO- and HLA-compatible platelet donors were identified and convened to donate forthe surgery and in case of emergency. Bleeding was prevented withprophylacticHLA-matched platelet transfusion and tranexamic acid. After transplant, diuresis started immediately with excellent graft function and no severe bleeding. However, after week 5, several episodes of macroscopic hematuria occurred, with obstruction and anuria. The double J ureteric stent was replaced 4 times in 2 months. Finally, the ureteric stent was removed 9 months later. At 22 months after kidney transplant, the patient has a normal graft function and no further bleeding has occurred, underlying the importance of multidisciplinary management.

Asymptomatic bacteriuria in pediatric kidney transplant recipients: to treat or not to treat? A retrospective study.

BACKGROUND: Urinary tract infections (UTI) are common infectious complications in kidney transplant recipients (KTR); asymptomatic bacteriuria (AB) is also frequent. It is unclear whether treatment of AB reduces subsequent UTI in KTR; no guideline is available in pediatric KTR. In this retrospective study, we analyzed the incidence of AB in pediatric KTR and the impact of screening and treating AB on the onset of subsequent UTI. METHODS: Thirty-seven pediatric patients were included. Inclusion criteria were the occurrence of one or more episodes of AB between 2 and 24 months post-renal transplantation. Primary outcome was the cumulative incidence of acute pyelonephritis (APN) or lower urinary tract infections (LUTI) occurring between 2 and 24 months post-renal transplantation. RESULTS: Thirty-seven patients presented 171 AB episodes. One hundred sixty-four AB episodes were untreated (95.9%); among them, 150 episodes (91.5%) were not followed by a clinical infection. Ten episodes (6.1%) led to APN, and 4 (2.4%) to LUTI. There were 53 episodes of APN: 10 (18.9%) after untreated AB and 43 (81.1%) de novo. There were 11 episodes of LUTI: 4 (36.4%) after untreated AB and 7 (63.6%) de novo. Multi-drug resistant bacteria were present in 27% of the patients and in 20% of patients with pre-existing uropathy. CONCLUSIONS: Our results are not in favor of systematic treatment of AB in pediatric KTR. Notably, limitation of antibiotic treatment is an urgent and important health issue in this population, in order to reduce multi-drug resistant bacteria emergence.

Effect of different rituximab regimens on B cell depletion and time to relapse in children with steroid-dependent nephrotic syndrome.

BACKGROUND: Several studies have demonstrated that rituximab (RTX) improves relapse-free survival in patients with steroid-dependent nephrotic syndrome (SDNS). However, these studies used various RTX regimens and there are few data comparing these regimens in children with SDNS. In this retrospective study, we assessed the effect of three different initial RTX regimens on both time to B cell reconstitution and to first relapse. METHODS: Sixty-one SDNS patients receiving a first course of RTX were included. Group 1 received one injection of 100 mg/m2, group 2 received one injection of 375 mg/m2, and group 3 received two injections of 375 mg/m2 at day 0 and day 7. Time to B cell reconstitution and time to first relapse and respective risk factors were studied. RESULTS: Median time to B cell reconstitution was 2.5 [1.8-3.5], 5.0 [3.9-6.0], and 6.6 [4.6-7.8] months in groups 1, 2, and 3, respectively. RTX regimen was associated with time to B cell reconstitution (HRs group 2 vs. 3, 4.07 [1.96-8.48]; group 1 vs. 3, 11.13 [4.04-30.67]). One-year relapse-free survival was 50% [58-77], 59% [42-76], and 72% [46-87] in groups 1, 2, and 3, respectively. RTX regimen was associated with risk of relapse (HRs group 2 vs. 3, 1.55 [0.51-4.65]; group 1 vs. 3, 4.98 [1.15-21.60]). CONCLUSIONS: The initial dose of rituximab impacts time to B cell reconstitution and the probability of relapse. Risk of relapse is also associated with patient characteristics, suggesting that RTX regimen could be modified for each patient to balance efficacy, cost, and side effects.

Effect of nonsteroidal anti-inflammatory drugs in children with Bartter syndrome.

BACKGROUND: Bartter syndrome (BS) is a salt-wasting tubulopathy with induced expression of cyclooxygenase-2 in the macula densa, leading to increased prostaglandin production and hyperreninemia. Nonsteroidal anti-inflammatory drugs (NSAIDs) are currently used in BS; however, there is limited information on the impact of NSAIDs at treatment initiation or the potential utility of plasma renin level to guide therapy in patients with BS. METHODS: We included 19 patients with BS treated with NSAIDs between 1994 and 2016. We assessed serum levels of renin, aldosterone, electrolytes, calcium, phosphorus, vitamin D, and intact parathyroid hormone (iPTH) before and after treatment initiation. We also recorded modifications in sodium and potassium supplements and changes in urine calcium. RESULTS: Median age at diagnosis was 0.9 months [IQR 0-6.9]. Seven patients had BS types 1 or 2, 12 had BS type 3 and two had no mutation identified. There was a trend towards a decrease in sodium chloride supplementation after initiation of NSAIDs. When defining response to treatment based on the normalization of plasma renin level, responders had a greater reduction in their electrolytes supplementation. NSAIDs treatment was associated with a reduction in urine calcium. Before treatment, half of the patients had elevated iPTH, but iPTH normalized following initiation of NSAIDs in all but one patient. CONCLUSIONS: This study confirms that NSAIDs reduce urine wasting of sodium and calcium in patients with BS. Monitoring serum renin levels may be useful to identify the lowest effective dose of NSAIDs that optimizes reduction of urine electrolyte losses.

Adverse Events under Tacrolimus and Cyclosporine in the First 3 Years Post-Renal Transplantation in Children.

BACKGROUND: Progress in immunosuppression has reduced acute rejection, graft loss and mortality after renal transplantation. Adverse drug reactions are well described in adults but few data are available in children. Our objectives were to analyse the adverse events reported in the first 3 years post-transplantation in children receiving tacrolimus or cyclosporine-based immunosuppression and compare them with the information of the Summary of Product Characteristics. METHODS: This retrospective study included all children who underwent a renal transplant at Hospital Robert Debré between 2002 and 2015. Initial immunosuppression was based on induction, calcineurin inhibitor, mycophenolate mofetil and corticosteroids. Adverse events were collected from medical records and coded using the Medical Dictionary for Regulatory Activities and the implications of tacrolimus and cyclosporine analysed. Statistical analyses were performed using SAS 9.4. RESULTS: One hundred and twenty-five children were included. During the observation period [2.7 years (0.6-4.3)], 105 patients received tacrolimus and 39 received cyclosporine. The incidence rate for gastrointestinal disorders was 0.128 and 0.056 by patient-years of exposure (p < 0.05), under tacrolimus and cyclosporine schedules. For neutropenia, it was 0.064 and 0.014 (p < 0.05). The frequencies of toxic nephropathy and gastrointestinal pain were higher than those in the Summary of Product Characteristics of tacrolimus (> 20%) and cyclosporine (> 10%). Cosmetic events for cyclosporine and neutropenia for tacrolimus were frequently observed (18 and 14.3%, respectively), although uncommon in the Summary of Product Characteristics. CONCLUSIONS: The exposure-adjusted incidence rate of gastrointestinal disorders and neutropenia was higher in children under the tacrolimus schedule. Our findings contribute to the evaluation of the benefit-risk balance of immunosuppressive therapy following paediatric renal transplantation.

Hypernatremia and acute pancreatitis in chronic kidney disease: back to the salt mines. Questions.

BACKGROUND: Acute pancreatitis can be a life-threatening complication in patients with chronic kidney disease (CKD), especially in kidney transplant recipients. CASE DIAGNOSIS/TREATMENT: The patient was 7 years old when he received renal transplantation for CKD secondary to posterior urethral valves. Two years later, he presented with severe necrotizing pancreatitis (Ranson's score 5, Balthazar's score 8). Viral and genetic testing came back negative; pancreatitis was attributed to the patient's treatments (prednisone, trimethoprim-sulfamethoxazole, and everolimus). Twenty days later, necrotized pancreatic cysts had formed. Two drains were surgically inserted into the abdomen, and continuous cyst lavage was started with normal saline solution. Two days later, blood tests revealed severe hypernatremia and hypokalemia. We suspected unwanted peritoneal dialysis had occurred because of the high sodium chloride content and the absence of potassium in the normal saline solution being used for cyst lavage. We switched to a peritoneal dialysis solution for the lavage, leading to complete correction of hydroelectrolytic disorders. CONCLUSION: Acute pancreatitis is a frequent and potentially severe complication in CKD patients. It should be suspected in the presence of nonspecific symptoms, such as abdominal pain or vomiting. Rigorous monitoring of electrolytes is also mandatory for managing CKD patients with acute pancreatitis.

Mycophenolate mofetil in steroid-dependent idiopathic nephrotic syndrome.

BACKGROUND: Prospective studies have established the mycophenolate mofetil (MMF) efficiency in childhood idiopathic nephrotic syndrome (INS) but reports on the long-term outcome are lacking. Moreover, the search for factors influencing its efficiency would be useful to define its place among the other treatments. METHODS: We performed a monocentric retrospective study including 96 children with steroid-dependent INS followed for 4.7 years (median) (IQ 3-6) after the onset of MMF treatment. The characteristics of responder patients (n = 74), as defined by a 50 % decrease of relapse rate and/or a 60 % decrease of steroid dose, and of non-responder patients (n = 22) were compared by univariate analysis and multivariate logistic regression. RESULTS: Withdrawal of prednisone was achieved in 48/96 patients after a median duration of 18.1 months (IQ 7.8-30.0) of MMF. Only 26/48 patients did not relapse under MMF alone. After MMF was stopped in these patients, only six remained in remission without any treatment at last follow-up. Responders had a shorter time to remission at the first flare (9.5 vs. 15 days, p = 0.02), a shorter disease duration prior to the onset of MMF (22.2 vs. 94.5 months, p = 0.001), and were younger at the MMF initiation (6.7 vs. 10.1 years, p = 0.02) than non-responder patients. The age of MMF initiation was an independent factor associated with efficiency (OR = 0.80, 95 % CI [0.69, 0.93], p < 0.01). CONCLUSIONS: MMF is more efficient in young patients treated early in the disease course. Nevertheless, MMF has no remnant effect while nearly all patients relapsed after withdrawal of the drug.

Cinacalcet in hyperparathyroidism management after pediatric renal transplantation.

Secondary hyperparathyroidism is often associated with end stage renal disease; even after renal transplantation, hyperparathyroidism may persist, and is responsible for hypercalcemia, hypophosphatemia and elevated parathyroid hormone (iPTH) levels. Parathyroid hyperplasia is frequently associated with persistent hyperparathyroidism, and may require a surgical treatment. Here, we report hyperparathyroidism along with parathyroid hyperplasia in a 7-year-old child, which persisted after renal transplant. Calcitonin and pamidronate failed to decrease serum calcium levels; clodronate was also inefficient. Cinacalcet therapy normalized serum calcium and phosphorus levels, and decreased iPTH levels in 3 months; a severe parathyroid hyperplasia was also corrected under calcimimetic therapy. In conclusion, we report in a child that hypercalcemia associated with secondary hyperparathyroidism can be corrected with cinacalcet after pediatric renal transplantation. We also show that parathyroid hyperplasia can regress under calcimimetic therapy in a transplanted child, making surgery unnecessary.

Population pharmacokinetics and pharmacogenetics of once daily prolonged-release formulation of tacrolimus in pediatric and adolescent kidney transplant recipients.

BACKGROUND AND OBJECTIVES: Tacrolimus(PR) is a new prolonged-release once-daily formulation of the calcineurin inhibitor tacrolimus, currently used in adult transplant patients. As there are no pharmacokinetic data available in pediatric kidney transplant recipients, the aims of this study were to develop a population pharmacokinetic model of tacrolimus(PR) in pediatric and adolescent kidney transplant recipients and to identify covariates that have a significant impacts on tacrolimus(PR) pharmacokinetics, including CYP3A5 polymorphism. METHODS: Pharmacokinetic samples were collected from 22 pediatric kidney transplant patients. Population pharmacokinetic analysis was performed using NONMEM. Pharmacogenetic analysis was performed on the CYP3A5 gene. RESULTS: The pharmacokinetic data were best described by a one-compartment model with first order absorption and lag-time. The weight normalized oral clearance CL/F [CL/F/ (weight/70)(0.75)] was lower in patients with CYP3A5 3/3 as compared to patients with the CYP3A5 1/3 (32.2 ± 10.1 vs. 53.5 ± 20.2 L/h, p = 0.01). CONCLUSIONS: The population pharmacokinetic model of tacrolimus(PR) was developed and validated in pediatric and adolescent kidney transplant patients. Body weight and CYP3A5 polymorphism were identified as significant factors influencing pharmacokinetics. The developed model could be useful to optimize individual pediatric tacrolimus (PR) dosing regimen in routine clinical practice.

Limited sampling strategy using Bayesian estimation for estimating individual exposure of the once-daily prolonged-release formulation of tacrolimus in kidney transplant children.

BACKGROUND: A limited sampling strategy (LSS) for estimating the area under the curve (AUC) of the prolonged-release formulation of tacrolimus (tacrolimus(PR)) is not available in pediatric patients, although the method is of real benefit to children. The objective of this study was to develop and validate a reliable and clinically applicable LSS using Bayesian estimation for estimating tacrolimus(PR) AUC in pediatric kidney transplant patients METHODS: The original tacrolimus pharmacokinetic dataset consisted of 22 full profiles from 22 pediatric kidney transplant patients. The Bayesian estimation method was used to develop the LSS. External validation was performed in an independent validation group which consisted of 20 full pharmacokinetic profiles from 12 pediatric kidney transplant patients. RESULTS: Bayesian estimator using C0h C2h and C3h gave the best predictive performance with a mean prediction error of 2.2 % in the external validation dataset. There was no correlation between the prediction error and age. The Bland-Altman analysis showed that the mean difference between the reference and Bayesian-estimated AUC0-24 was 3.5 (95 % confidence interval -3.5-10.5) ng h/mL CONCLUSIONS: A reliable and clinically applicable LSS for estimating AUC0-24 of tacrolimus(PR) was determined and validated in children. The prediction was unbiased and precise. It can be used as a routine procedure to perform AUC-based tacrolimus(PR) dosage optimization in pediatric renal transplant patients.

Pharmacogenetic determinant of the drug interaction between tacrolimus and omeprazole.

A 17-year-old adolescent with acute nephrotoxicity had CYP3A4-5, CYP2C19, and ABCB1 genotyping performed to understand a suspected drug interaction between tacrolimus and omeprazole. The determinant role of individual pharmacogenetic profile in the occurrence of tacrolimus nephrotoxicity is presented and discussed.

Limited sampling strategy for estimating individual exposure of tacrolimus in pediatric kidney transplant patients.

BACKGROUND: Limited sampling strategies (LSS) for estimating the area under the curve (AUC(0-12h)) of tacrolimus and optimizing dosage adjustment are not currently used or fully validated in pediatric patients, although the method is of real benefit to children. The objective of the present study was to develop and validate reliable and clinically applicable LSS using Bayesian estimation and the multiple regression analysis for estimating tacrolimus AUC in pediatric kidney transplant patients. METHODS: The original tacrolimus pharmacokinetic dataset consists of 50 full profiles from 50 pediatric kidney transplant patients. Two LSS based on Bayesian estimator or multiple regression analysis to calculate tacrolimus AUC were developed and then compared. External validation was prospectively performed in an independent validation group, which consisted of 42 full pharmacokinetic profiles from 20 pediatric kidney transplant patients. RESULTS: Bayesian estimators using C(0h), C(1h) or C(2h), and C(3h) gave the best predictive performance, the external validation having a mean prediction bias of 1% and mean imprecision of 5.5%. The multiple regression analysis using C(0h), C(1h), and C(3h) gave the best correlation (r² = 0.953) between estimated and referenced AUCs with a mean prediction bias of 4.2% and mean precision of 8.3% in external validation dataset. CONCLUSIONS: The prediction of AUC using developed LSS was unbiased and precise. The age and time after transplantation did not influence the predictive performance. Such LSS approach will help guiding tacrolimus therapeutic drug monitoring based on AUC in pediatric kidney transplant patients.

Glucocorticoid pharmacokinetics and growth retardation in children with renal transplants.

Long-term glucocorticoid treatment contributes to the growth retardation in children after renal transplantation. We investigated whether determination of prednisone (PN) and prednisolone (PL) in plasma and PN, PL, and 6-beta-hydroxyprednisolone (betaOH-PL) in urine could help to predict growth. PN and PL pharmacokinetics were studied in 36 children, from 5 to 15 years of age, receiving daily (D) or alternate-day (AD) oral PN treatment. Statural growth velocity was evaluated over a 1-year period. We compared three groups of children according to the growth kinetics during the study year (catch-up, stable, or decline) for clinical and pharmacokinetic parameters. A multiple linear regression analysis was performed in order to determine pharmacokinetic parameters able to explain height 1 year after inclusion. Height at the beginning of the study, creatinine clearance, and type of D or AD treatment explained 94.2% of height variance 1 year after inclusion. Only PL clearance was associated with growth evolution, but introduction of PL clearance in the multivariate model did not improve the variance of height accounted for by the previous model. We, therefore, do not recommend using glucocorticoid pharmacokinetics to predict growth retardation in children with renal transplantation.

Relationship between CD8+ T-cell phenotype and function, Epstein-Barr virus load, and clinical outcome in pediatric renal transplant recipients: a prospective study.

BACKGROUND: The authors studied the relationship between the dynamics of Epstein-Barr virus (EBV) load, CD8 T-cell activation and differentiation, and EBV-associated symptoms in 25 children after kidney transplantation (Tx). METHODS: Twenty-two patients were enrolled at the time of Tx and three at diagnosis of EBV-induced post-transplant lymphoproliferative disease (PTLD). EBV load was serially measured by a semiquantitative method of DNA amplification in blood cells. The percentages of activated (human leukocyte antigen-DR) and of effector-memory (CD28) CD8 circulating cytolytic T lymphocytes (CTL) were serially evaluated by flow cytometry. The cytotoxic potential of CTL was assessed by a CD3-redirected cytotoxic assay. RESULTS: For three children with post-Tx uncomplicated primary EBV infection, EBV load peaked by months 1 to 2 after Tx and declined spontaneously by months 3 to 6, whereas expansion of activated and effector-memory CTL was absent (one case) or transient and moderate (two cases). In 15 patients who were EBV-seropositive before Tx and who did not develop EBV-PTLD, transient elevation of EBV load but no noticeable changes in CTL phenotype were observed. In contrast, in one child who was also EBV-seropositive before Tx but who developed EBV-PTLD, a major and sustained elevation of EBV load and of activated and effector-memory CTL was observed. In three patients retrospectively enrolled at diagnosis of EBV-PTLD, sustained elevation of both viral load and activated T cells was also noticed. Finally, increased cytotoxic activity correlated with increased level of activated CTL. CONCLUSIONS: An association between high and sustained T-cell activation, EBV load, and the occurrence of EBV-PTLD was observed. Furthermore, intense cytotoxic activity was observed in EBV-PTLD, with favorable outcome.