CTOTC-08: A multicenter randomized controlled trial of rituximab induction to reduce antibody development and improve outcomes in pediatric lung transplant recipients.

We conducted a randomized, placebo-controlled, double-blind study of pediatric lung transplant recipients, hypothesizing that rituximab plus rabbit anti-thymocyte globulin induction would reduce de novo donor-specific human leukocyte antigen antibodies (DSA) development and improve outcomes. We serially obtained clinical data, blood, and respiratory samples for at least one year posttransplant. We analyzed peripheral blood lymphocytes by flow cytometry, serum for antibody development, and respiratory samples for viral infections using multiplex PCR. Of 45 subjects enrolled, 34 were transplanted and 27 randomized to rituximab (n = 15) or placebo (n = 12). No rituximab-treated subjects versus five placebo-treated subjects developed de novo DSA with mean fluorescence intensity >2000. There was no difference between treatment groups in time to the primary composite outcome endpoint (death, bronchiolitis obliterans syndrome [BOS] grade 0-p, obliterative bronchiolitis or listing for retransplant). A post-hoc analysis substituting more stringent chronic lung allograft dysfunction criteria for BOS 0-p showed no difference in outcome (p = .118). The incidence of adverse events including infection and rejection episodes was no different between treatment groups. Although the study was underpowered, we conclude that rituximab induction may have prevented early DSA development in pediatric lung transplant recipients without adverse effects and may improve outcomes (Clinical Trials: NCT02266888).

Auto-inflammation and auto-immunity pathways are associated with emergence of BOS in pediatric lung transplantation.

BACKGROUND: Long-term survival after lung transplantation (LTx) is limited by chronic lung allograft dysfunction (CLAD). METHODS: We report an analysis of cytokine profiles in bronchoalveolar lavage samples collected during a prospective multicenter non-interventional trial primarily designed to determine the impact of community-acquired respiratory viral infections (CARV) in outcomes after pediatric LTx. In this analysis, we identify potential biomarkers of auto-inflammation and auto-immunity associated with survival and risk of bronchiolitis obliterans (BOS) after LTx with cytokine analysis of bronchoalveolar lavage fluid (BALF) from 61 pediatric recipients. RESULTS: Higher IL-23 (p = .048) and IL-31 (p = .035) levels were associated with the risk of BOS, and lower levels of epithelial growth factor (EGF) (p = .041) and eotaxin (EOX) (p = .017) were associated with BOS. Analysis using conditional inference trees to evaluate cytokines at each visit associated with survival identified soluble CD30 (p < .001), pro-inflammatory cytokine IL-23 (p = .02), and sTNFRI (p = .01) below cutoff levels as associated with BOS-free survival. CONCLUSIONS: Our results indicate that post-LTx survival in children may be linked to activation of alternate pathways of the immune system that affect airway remodeling in addition to activation of "classical" pathways that have been described in adult LTx recipients. These may indicate pathways to target for intervention.

Developing an adolescent and adult Fontan Management Programme.

Patients with single-ventricle CHD undergo a series of palliative surgeries that culminate in the Fontan procedure. While the Fontan procedure allows most patients to survive to adulthood, the Fontan circulation can eventually lead to multiple cardiac complications and multi-organ dysfunction. Care for adolescents and adults with a Fontan circulation has begun to transition from a primarily cardiac-focused model to care models, which are designed to monitor multiple organ systems, and using clues from this screening, identify patients who are at risk for adverse outcomes. The complexity of care required for these patients led our centre to develop a multidisciplinary Fontan Management Programme with the primary goals of earlier detection and treatment of complications through the development of a cohesive network of diverse medical subspecialists with Fontan expertise.

Remote intervention engagement and outcomes in the Clinical Trials in Organ Transplantation in Children consortium multisite trial.

Remote interventions are increasingly used in transplant medicine but have rarely been rigorously evaluated. We investigated a remote intervention targeting immunosuppressant management in pediatric lung transplant recipients. Patients were recruited from a larger multisite trial if they had a Medication Level Variability Index (MLVI) ≥2.0, indicating worrisome tacrolimus level fluctuation. The manualized intervention included three weekly phone calls and regular follow-up calls. A comparison group included patients who met enrollment criteria after the subprotocol ended. Outcomes were defined before the intent-to-treat analysis. Feasibility was defined as ≥50% of participants completing the weekly calls. MLVI was compared pre- and 180 days postenrollment and between intervention and comparison groups. Of 18 eligible patients, 15 enrolled. Seven additional patients served as the comparison. Seventy-five percent of participants completed ≥3 weekly calls; average time on protocol was 257.7 days. Average intervention group MLVI was significantly lower (indicating improved blood level stability) at 180 days postenrollment (2.9 ± 1.29) compared with pre-enrollment (4.6 ± 2.10), p = .02. At 180 days, MLVI decreased by 1.6 points in the intervention group but increased by 0.6 in the comparison group (p = .054). Participants successfully engaged in a long-term remote intervention, and their medication blood levels stabilized. NCT02266888.

Evaluation of a change in cytomegalovirus prevention strategy following pediatric solid organ transplantation.

BACKGROUND: An optimal cytomegalovirus (CMV) prevention strategy following solid organ transplantation (SOT) remains uncertain. This study reports on the rates of CMV events following a change in a local prevention guideline involving increased surveillance, earlier transition to oral valganciclovir, and decreased CMV-immunoglobulin use. METHODS: A retrospective cohort study utilizing historical controls evaluated the rates of CMV invasive disease pre- and post-intervention among pediatric heart, liver, and kidney recipients. Outcomes were recorded for the 4 years pre- and post-intervention, 9/2009-10/2017. Logistic regression was used to estimate the risk of a CMV event. RESULTS: There was no difference in the rates of CMV invasive disease between the two study groups (P = 1). An increase in the detection of CMV events occurred (P = .04), predominantly asymptomatic CMV infection. This increase was independently associated with increased surveillance testing among high-risk heart and liver recipients, aOR 1.08 (1.06-1.12). Surprisingly, 28.9% of CMV events occurred during antiviral prophylaxis. CONCLUSIONS: Modification of the local CMV prevention guideline did not result in an increase in CMV invasive disease. CMV events occurred while on prophylaxis, highlighting a potential difference from adult solid organ transplant (SOT) and emphasizing the potential need for monitoring on prophylaxis in the pediatric population.

Epidemiology and persistence of rhinovirus in pediatric lung transplantation.

BACKGROUND: Infection with rhinovirus (HRV) occurs following pediatric lung transplantation. Prospective studies documenting frequencies, persistence, and progression of HRV in this at-risk population are lacking. METHODS: In the Clinical Trials in Organ Transplant in Children prospective observational study, we followed 61 lung transplant recipients for 2 years. We quantified molecular subtypes of HRV in serially collected nasopharyngeal (NP) and bronchoalveolar lavage (BAL) samples and correlated them with clinical characteristics. RESULTS: We identified 135 community-acquired respiratory infections (CARV) from 397 BAL and 480 NP samples. We detected 93 HRV events in 42 (68.8%) patients, 22 of which (23.4%) were symptomatic. HRV events were contiguous with different genotypes identified in 23 cases, but symptoms were not preferentially associated with any particular species. Nine (9.7%) HRV events persisted over multiple successive samples for a median of 36 days (range 18-408 days). Three persistent HRV were symptomatic. When we serially measured forced expiratory volume in one second (FEV1) in 23 subjects with events, we did not observe significant decreases in lung function over 12 months post-HRV. CONCLUSION: In conjunction with our previous reports, our prospectively collected data indicate that molecularly heterogeneous HRV infections occur commonly following pediatric lung transplantation, but these infections do not negatively impact clinical outcomes.

Pediatric heart-lung transplantation: A contemporary analysis of outcomes.

BACKGROUND: Pediatric heart-lung transplantation (HLT) is rare, and no report has analyzed patient outcomes since time of listing. We analyzed pediatric HLTs to understand risk factors for waitlist and post-HLT mortality. METHODS: All pediatric (<18 year old) HLT candidates were identified within the UNOS database (n = 573) and grouped by age, era, and by diagnosis. Logistical regression and Cox proportional hazard modeling identified risk factors for 6-month WL and overall post-transplant mortality. RESULTS: 209/573 (37%) HLT candidates were transplanted, 7% recovered, 42% died waiting, and 15% were removed for another/unknown reason. Diagnoses were primary pulmonary hypertension(n = 130), congenital heart disease(CHD) without Eisenmenger's syndrome (ES) (n = 65), CHD with ES (n = 73), and other (n = 305). Patients with a diagnosis other than CHD with ES (OR: 7.55, P = .001), on IV inotropic support (OR: 2.79, P < .001), and infants (OR: 2.20, P = .004) were associated with waitlist mortality. There has been a 56% reduction in HLTs across eras (Era 1:10.8/yr vs Era 2:4.7/yr). Risk factors for post-transplant mortality were ECMO (HR: 4.1, P = .016), and being infant (HR: 2.2, P = .04) or 1-11 years old (HR: 1.78, P = .015). ECMO patients have an 87% 2-year mortality rate with a median post-transplant survival of 64 days. Overall, post-transplant survival was unchanged (log-rank P = .067) between eras. Excluding ECMO patients, in the recent era 29 non-infant patients with primary pulmonary hypertension had 93% 1-year survival and 67% 5-year survival. CONCLUSIONS: Nearly 600 pediatric patients have been listed for HLT in UNOS, although numbers are decreasing in the current era. HLT for a patient on ECMO appears to be an ineffective strategy; however, in well-selected cohorts, HLT can provide considerable post-transplant survival.

Pediatric trichodysplasia spinulosa: A report of 2 cases and review of the literature.

Trichodysplasia spinulosa is a rare disorder caused by the ubiquitous trichodysplasia spinulosa-associated polyomavirus (TSPyV) and characterized clinically by predominately centrofacial, but often generalized, folliculocentric papules with protuberant keratinaceous spines. Although seroprevalence reaches up to 70% in adult populations, TSPyV causes clinical manifestations in a small percentage of patients who are immunosuppressed. Diagnosis can be made using typical clinical and histologic features, SV40T antibody immunostaining, and PCR of various tissues including the keratinaceous spine, skin, serum, urine, and CSF. Various topical and systemic medications have demonstrated variable success. Decreasing or discontinuing immunosuppression has also been shown to improve or alleviate clinical manifestations.

Absence of evidence that respiratory viral infections influence pediatric lung transplantation outcomes: Results of the CTOTC-03 study.

Based on reports in adult lung transplant recipients, we hypothesized that community-acquired respiratory viral infections (CARVs) would be a risk factor for poor outcome after pediatric lung transplant. We followed 61 pediatric lung transplant recipients for 2+ years or until they met a composite primary endpoint including bronchiolitis obliterans syndrome/obliterative bronchiolitis, retransplant, or death. Blood, bronchoalveolar lavage, and nasopharyngeal specimens were obtained with standard of care visits. Nasopharyngeal specimens were obtained from recipients with respiratory viral symptoms. Respiratory specimens were interrogated for respiratory viruses by using multiplex polymerase chain reaction. Donor-specific HLA antibodies, self-antigens, and ELISPOT reactivity were also evaluated. Survival was 84% (1 year) and 68% (3 years). Bronchiolitis obliterans syndrome incidence was 20% (1 year) and 38% (3 years). The primary endpoint was met in 46% of patients. CARV was detected in 156 patient visits (74% enterovirus/rhinovirus). We did not find a relationship between CARV recovery from respiratory specimens and the primary endpoint (hazard ratio 0.64 [95% confidence interval: 0.25-1.59], P = .335) or between CARV and the development of alloimmune or autoimmune humoral or cellular responses. These findings raise the possibility that the immunologic impact of CARV following pediatric lung transplant is different than that observed in adults.

Anellovirus loads are associated with outcomes in pediatric lung transplantation.

Anelloviruses are DNA viruses ubiquitously present in human blood. Due to their elevated levels in immunosuppressed patients, anellovirus levels have been proposed as a marker of immune status. We hypothesized that low anellovirus levels, reflecting relative immunocompetence, would be associated with adverse outcomes in pediatric lung transplantation. We assayed blood samples from 57 patients in a multicenter study for alpha- and betatorquevirus, two anellovirus genera. The primary short-term outcome of interest was acute rejection, and longer-term outcomes were analyzed individually and as "composite" (death, chronic rejection, or retransplant within 2 years). Patients with low alphatorquevirus levels at 2 weeks post-transplantation were more likely to develop acute rejection within 3 months after transplant (P = .013). Low betatorquevirus levels at 6 weeks and 6 months after transplant were associated with death (P = .047) and the composite outcome (P = .017), respectively. There was an association between low anellovirus levels and adverse outcomes in pediatric lung transplantation. Alphatorquevirus levels were associated with short-term outcomes (ie, acute rejection), while betatorquevirus levels were associated with longer-term outcomes (ie, death, or composite outcome within 2 years). These observations suggest that anelloviruses may serve as useful biomarkers of immune status and predictors of adverse outcomes.

Lung Transplantation for FLNA-Associated Progressive Lung Disease.

OBJECTIVE: To describe a series of patients with pathogenic variants in FLNA and progressive lung disease necessitating lung transplantation. STUDY DESIGN: We conducted a retrospective chart review of 6 female infants with heterozygous presumed loss-of-function pathogenic variants in FLNA whose initial presentation was early and progressive respiratory failure. RESULTS: Each patient received lung transplantation at an average age of 11 months (range, 5-15 months). All patients had pulmonary arterial hypertension and chronic respiratory failure requiring tracheostomy and escalating levels of ventilator support before transplantation. All 6 patients survived initial lung transplantation; however, 1 patient died after a subsequent heart-lung transplant. The remaining 5 patients are living unrestricted lives on chronic immunosuppression at most recent follow-up (range, 19 months to 11.3 years post-transplantation). However, in all patients, severe ascending aortic dilation has been observed with aortic regurgitation. CONCLUSIONS: Respiratory failure secondary to progressive obstructive lung disease during infancy may be the presenting phenotype of FLNA-associated periventricular nodular heterotopia. We describe a cohort of patients with progressive respiratory failure related to a pathogenic variant in FLNA and present lung transplantation as a viable therapeutic option for this group of patients.

Risk and outcomes of pulmonary fungal infection after pediatric lung transplantation.

BACKGROUND: Prospective studies to determine associated risk factors and related outcomes for pulmonary fungal infection (PFI) after pediatric lung transplant (PLT) are lacking. METHODS: NIH-sponsored Clinical Trials in Organ Transplantation in Children enrolled PLT candidates, collecting data prospectively for 2 years post-transplant. Demographics, signs/symptoms, radiology, pathology and microbiology were collected. Analyses evaluated for PFI-related risks and outcomes. RESULTS: In 59 PLT, pre-transplant fungal colonization occurred in 6 donors and 15 recipients. Cystic fibrosis (CF) was associated with pre-transplant colonization (P < .01). Twenty-five (42%) PLT had 26 post-transplant colonizations (median = 67 days, range = 0-750 days) with Candida (13), Aspergillus (4), mold (6) or yeast (3). Post-PLT colonization was not associated with CF, age, or pre-PLT colonization. Thirteen PFIs occurred in 10 (17%) patients, 3 proven (Candida species) and 10 probable (Candida [3], Aspergillus [3], Penicillium [3], and mold [1]). Pulmonary fungal infection was preceded by post-PLT colonization with the same organism in 4 of 13 PFI, but post-PLT colonization did not predict subsequent PFI (P = .87). Older age at transplant was a risk for PFI (P < .01). No mortality was attributed to PFI. Prophylaxis use was not associated with decreased post-PLT colonization (P = .60) or PFI (P = .48). CONCLUSION: In PLT, PFI and fungal colonization are common but without associated mortality. Post-PLT colonization did not predict PFI. Optimal prevention strategies require additional study.

Epstein-Barr viral loads do not predict post-transplant lymphoproliferative disorder in pediatric lung transplant recipients: A multicenter prospective cohort study.

Prediction of PTLD after pediatric lung transplant remains difficult. Use of EBV VL in WB has been poorly predictive, while measurement of VL in BAL fluid has been suggested to have enhanced utility. The NIH-sponsored Clinical Trials in Organ Transplantation in Children (CTOTC-03) prospectively obtained serial quantitative measurements of EBV PCR in both WB and BAL fluid after pediatric lung transplantation. Descriptive statistics, contingency analyses, and Kaplan-Meier analyses evaluated possible association between EBV and PTLD. Of 61 patients, 34 (56%) had an EBV+PCR (at least once in WB or BAL). EBV donor (D)+patients more often had a positive PCR (D+/recipient (R)-: 13/18; D+/R+: 14/23) compared to EBV D- patients (6/17). Several D-/R- (5/12) patients developed EBV, but none developed PTLD. All four PTLD patients were D+/R- with EBV+PCR. Neither the time to first EBV+PCR nor the CT for PCR positivity in BAL or WB was statistically different between those with and without PTLD. Having an EBV-seropositive donor was associated with increased risk of EBV+PCR in WB. EBV load in BAL was not predictive of PTLD.

Body mass index percentage and survival in pediatric patients listed for lung transplantation: A modern-era multi-institutional analysis.

BACKGROUND: Prior studies suggest that being underweight by body mass index percentiles (BMI%) or thinness grade did not affect post-transplant survival in pediatric lung transplant (LTx) recipients regardless of cystic fibrosis (CF) or non-CF diagnosis. Graft and overall survival from the time of listing was instead evaluated based on listing BMI%, the current standard of practice for BMI definitions in pediatrics, to ascertain the impact of a "severely low" subcategory. METHODS: The UNOS registry was queried for children listed for LTx (aged 2 to <18 years) from January 1986 to March 2020. BMI% at listing and transplant were calculated per CDC guidelines according to age in years, sex, and reported BMI%. Patients were divided by listing BMI%: severely low (<3rd), low (3-<5th), normal (5-<85th), overweight (85-<95th), and obese (≥95th). Kaplan-Meier curves were generated to assess differences in overall survival since listing based on BMI% classes. Cox proportional-hazards models were developed to assess risk factors for overall and graft survival, including listing BMI%, transplant listing era (≥2005), and listing age, by reporting hazard ratios (HR). RESULTS: Listing BMI% was calculable for 1,876 patients. The proportion of patients with CF differed significantly between BMI% groups (p < 0.001). Patients listed with a non-CF diagnosis comprised 34% of those in the severely low category, and 88% of those listed with an obese BMI%. Compared to patients with a normal listing BMI%, the cohort with severely low BMI% had worse overall survival regardless of LTx (p = 0.009) and graft survival (p = 0.034). Compared to patients with a low BMI%, those with a severely low BMI% had significantly poorer graft survival as well (p = 0.040). Mean graft survival was not significantly different between groups that remained at listing BMI% vs those that improved in category despite an overall small sample size. Independent predictors of poorer survival from the time of listing include severely low vs low-normal BMI% (HR = 1.20) and listing age (HR = 1.02). CONCLUSION: The proportion of children listed at severely low BMI% has steadily decreased with time, yet pediatric LTx candidates listed with a severely low BMI% had poorer graft and overall survival compared to those of normal BMI%. Severely low listing BMI% was an independent prognostic factor for higher mortality risk from the time of placement on the waitlist. BMI% may be a modifiable target for improving survival regardless of transplantation.

Rapid and progressive pulmonary fibrosis in 2 families with DNA repair deficiencies of undetermined etiology.

Known genetic causes of pediatric interstitial lung disease include disorders of surfactant metabolism, telomerase, and DNA repair. We report 4 children from 2 families with rapidly progressive and fatal pulmonary fibrosis. A novel DNA repair defect unrelated to the ataxia-telangiectasia mutated gene was found in 1 child from each family.

Lung Transplantation Advanced Prediction Tool: Determining Recipient's Outcome for a Certain Donor.

BACKGROUND: Many risk-prediction models for lung transplantation are centered on recipient characteristics and do not account for impact of donor and transplant-related factors or only examine short-term outcomes (eg, predicted 1-y survival). We sought to develop a comprehensive model guiding recipient-donor matching. METHODS: We identified double lung transplant recipients (≥12 y old) in the United Network for Organ Sharing Registry (2005-2020) to develop a risk scoring tool. Cohort was divided into derivation and validation sets. A total of 42 recipient, donor, and transplant factors were included in the analysis. Lasso method was used for variable selection. Survival was estimated using Cox-proportional hazard models. An interactive web-based tool was developed for clinical use. RESULTS: A derivation cohort (n = 10 660) informed the model with 13-recipient, 4-donor, and 2-transplant variables. Adjusted risk scores were computed for every transplant and grouped into 3 clusters. Model-estimated survival probabilities were similar to the observed in the validation cohort (n = 4464) for all clusters. The mortality increases for medium- and high-risk groups was similar in both derivation and validation cohorts (C statistics for 1-, 5-, and 10-y survival were 0.67, 0.64, and 0.72, respectively). The web-based application estimated 1-, 5-, 10-y survival and half-life for low- (92%, 73%, 52%; 10.5 y), medium- (89%, 62%, 38%; 7.3 y), and high-risk clusters (85%, 52%, 26%; 5.2 y). CONCLUSIONS: Advanced methods incorporating machine/deep learning led to a risk scoring model (including recipient, donor, and transplant factors) and a web-based clinical tool providing short- and long-term survival probabilities for recipient-donor matches. This will enable risk-based matching that could improve utilization of and benefit from a limited donor pool.

Heart-Lung Transplant via an Eighth-Time Sternotomy.

We report a combined heart-lung transplantation following seven prior sternotomies in a patient born with a transitional atrioventricular septal defect. Previous surgeries to repair and replace the mitral valve led to pulmonary vein stenosis and pulmonary vascular disease. Eighth-time sternotomy and significant vascular adhesions led to a prolonged operation and to placing the heart-lung block anterior to the phrenic nerves. Despite this, the patient was ready for discharge after two weeks and continues to do well over nine months later. As more patients survive multiple cardiac palliations with some developing pulmonary vascular disease, heart-lung transplantation may become relevant again.

Serum KL-6 level and the development of bronchiolitis obliterans syndrome in lung transplant recipients.

KL-6 is a glycoprotein expressed by pulmonary epithelial cells, and its serum level has been used as a marker of disease activity in a variety of respiratory illnesses. Previously, we showed that KL-6 was elevated in lung transplant recipients diagnosed with BOS. In this study, we followed serum KL-6 levels and lung functions prospectively in lung transplant recipients who were within the first five-yr post-transplant and had no evidence of BOS at the time of study entry. Mean peak KL-6 levels were 596.16 ± 309.32 U/mL in the nine recipients who developed BOS compared to 352.41 ± 140.68 in 36 recipients who did not (p = 0.05). Six of the nine patients with BOS had an absolute rise in KL-6 above baseline level >200 U/mL compared to two of the 37 who had the same increase in KL-6 but did not develop BOS. Using the 200 U/mL elevation of KL-6 from baseline as a threshold for a positive test would produce a sensitivity of 67%, specificity of 95%, PPV of 75%, and a NPV of 92%. In addition, mean KL-6 levels of patients during acute rejection were not significantly elevated compared to the prerejection mean KL-6 levels (p = 0.71). We conclude that serum KL-6 is a relatively specific marker of BOS in lung transplant recipients.

Cerebral aspergillosis caused by Aspergillus granulosus.

Disseminated disease by Aspergillus granulosus has been reported only once previously in a cardiac transplant recipient. We report a fatal central nervous system infection in a lung transplant recipient. Key features of this species in the section Usti include growth at 37 degrees C and large, randomly spaced aggregates of variably shaped Hülle cells.

Post-transplant lymphoproliferative disease in pediatric lung transplant recipients: recent advances in monitoring.

To investigate the clinical validity of newer diagnostic tests such as monitoring of EBVqPCR and lymphocyte function assay ImmuKnow in helping to diagnose PTLD in pediatric lung transplant recipients. Single-center, retrospective case-control study. CsA trough levels, EBVqPCR and ImmuKnow (Cyclex Inc., Columbia, MD, USA) levels were measured serially as part of routine care. Re-transplant patients and patients who did not reach 12 months post-transplant at the time of analysis were excluded. Twenty-seven patients met the inclusion criteria. The study group consisted of seven patients who developed PTLD, five of which were EBV- recipients who received EBV+ lungs. The rest of the eligible patients served as controls. Median time to develop PTLD was 273 days (range: 166-343). One, two, three, six, and nine months after transplant, mean (+/-s.d.) CsA trough whole blood levels (ng/mL) were not different between the two groups: 378 +/- 38, 390 +/- 52, 402 +/- 89, 359 +/- 42, and 342 +/- 115, vs. 416 +/- 105, 347 +/- 64, 337 +/- 78, 333 +/- 86, and 281 +/- 54 [PTLD vs. no-PTLD, respectively (p > 0.05 for all time points)]. Mean (+/-s.d.) EBVqPCR levels (copies/mL) measured at three, six, and nine months post-transplant were significantly elevated in PTLD group compared to no-PTLD group: 84 +/- 99, 3384 +/- 7428 and 839 +/- 1444 vs. 9 +/- 26, 8 +/- 36 and 32 +/- 136, respectively (p < 0.05 for all time points). Mean (+/-s.d.) ImmuKnow levels (ATP ng/mL) at three, six, and nine months post-transplant were significantly lower in the PTLD group when compared with no-PTLD group: 144 +/- 67, 137 +/- 110, and 120 +/- 153 vs. 290 +/- 161, 300 +/- 162, and 293 +/- 190, respectively (p < 0.05 for all time points). Close monitoring of EBV viral load by qPCR and the degree of immunosuppression via ImmuKnow may guide physicians to reach the diagnosis of PTLD early.