Late acute rejection: incidence, risk factors, and effect on graft survival and function

Association of HLA B- and T-cell molecular mismatches with HLA antibodies, rejection, and graft survival in pediatric kidney transplantation

BACKGROUND

Optimizing graft survival and diminishing human leukocyte antigen (HLA) sensitization are essential for pediatric kidney transplant recipients. More precise HLA matching predicting epitope mismatches could reduce alloreactivity. We investigated the association of predicted HLA B- and T-cell molecular mismatches with the formation of de novo donor-specific antibodies, HLA antibodies, rejection, and graft survival.

METHODS

Forty-nine pediatric kidney transplant recipients transplanted from 2009 to 2020 were retrospectively studied. Donors and recipients were high-resolution HLA typed, and recipients were screened for HLA antibodies posttransplant. HLA-EMMA (HLA Epitope MisMatch Algorithm) and PIRCHE-II (Predicted Indirectly ReCognizable HLA Epitopes) predicted the molecular mismatches. The association of molecular mismatches and the end-points was explored with logistic regression.

RESULTS

Five recipients (11%) developed de novo donor-specific antibodies. All five had de novo donor-specific antibodies against HLA class II, with four having HLA-DQ antibodies. We found no associations between PIRCHE-II or HLA-EMMA with de novo donor-specific antibodies, HLA sensitization, graft loss, or rejection. However, we did see a tendency towards an increased odds ratio in PIRCHE-II predicting de novo donor-specific antibodies formation, with an odds ratio of 1.12 (95% CI: 0.99; 1.28) on HLA class II.

CONCLUSION

While the study revealed no significant associations between the number of molecular mismatches and outcomes, a notable trend was observed - indicating a reduced risk of dnDSA formation with improved molecular match. It is important to acknowledge, however, that the modest population size and limited observed outcomes preclude us from making definitive conclusions.

Antibody-mediated rejection in pediatric kidney transplant recipients: A report from the Pediatric Nephrology Research Consortium

BACKGROUND

Antibody-mediated rejection (AMR) is a major cause of kidney allograft loss. There is a paucity of large-scale pediatric-specific data regarding AMR treatment outcomes.

METHODS

Data were obtained from 14 centers within the Pediatric Nephrology Research Consortium. Kidney transplant recipients aged 1-18 years at transplant with biopsy-proven AMR between 2009 and 2019 and at least 12 months of follow-up were included. The primary outcome was graft failure or an eGFR <20 mL/min/1.73 m2 at 12 months following AMR treatment. AMR treatment choice, histopathology, and DSA class were also examined.

RESULTS

We reviewed 123 AMR episodes. Median age at diagnosis was 15 years at a median 22 months post-transplant. The primary outcome developed in 27.6%. eGFR <30 m/min/1.73 m2 at AMR diagnosis was associated with a 5.6-fold higher risk of reaching the composite outcome. There were no significant differences in outcome by treatment modality. Histopathology scores and DSA class at time of AMR diagnosis were not significantly associated with the primary outcome.

CONCLUSIONS

In this large cohort of pediatric kidney transplant recipients with AMR, nearly one-third of patients experienced graft failure or significant graft dysfunction within 12 months of diagnosis. Poor graft function at time of diagnosis was associated with higher odds of graft failure.

Follow-up biopsies identify high rates of persistent rejection in pediatric kidney transplant recipients after treatment of T cell-mediated rejection

BACKGROUND

Incomplete resolution of T cell-mediated rejection (TCMR) after treatment may not be detected with serum creatinine monitoring and is associated with donor-specific antibodies and chronic rejection. We evaluate the utility of follow-up biopsies (FUB) to identify and characterize rates of persistent TCMR after treatment in pediatric kidney transplant patients.

METHODS

Patients from two pediatric transplant centers performing standard of care FUB at 1.5-2 months after treatment for TCMR were included. FUB were evaluated for extent of rejection resolution (complete vs. incomplete) and grade. Clinical data at time of FUB and later were reported, where available.

RESULTS

Fifty-eight patients underwent FUB, at mean of 1.7 months (SD 0.7) post-index biopsy. Rejection grade on index biopsy was Banff borderline (≥i1t1 and

CONCLUSIONS

FUB were effective at detecting persistent rejection, which was common among pediatric transplant patients after standard TCMR treatment. Until more effective rejection treatments or sensitive biomarkers are available, FUB may be effectively utilized to identify patients with ongoing rejection who would benefit from further treatment.

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Key Words

• biopsy
• pediatric
• rejection

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MESH Headings

• Humans
• Child
• Kidney Transplantation/adverse effects
• T-Lymphocytes
• Follow-Up Studies
• Biopsy
• Treatment Outcome
• Transplant Recipients
• Graft Rejection
• Kidney/pathology

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Grants

• R01 DK126807 NIDDK NIH HHS

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Affiliation(s)

Adina Landsberg Department of Medicine, University of Calgary, Calgary, AB, Canada
S. Sikandar Raza Department of Pediatrics, University of Alabama Heersink School of Medicine, Birmingham, AL, United States
Michael E. Seifert Department of Pediatrics, University of Alabama Heersink School of Medicine, Birmingham, AL, United States
Tom D. Blydt-Hansen BC Children’s Hospital, Division of Nephrology, Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada

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Rejection markers in kidney transplantation: do new technologies help children?

Recent insights in allorecognition and graft rejection mechanisms revealed a more complex picture than originally considered, involving multiple pathways of both adaptive and innate immune response, supplied by efficient inflammatory synergies. Current pillars of transplant monitoring are serum creatinine, proteinuria, and drug blood levels, which are considered as traditional markers, due to consolidated experience, low cost, and widespread availability. The most diffuse immunological biomarkers are donor-specific antibodies, which are included in routine post-transplant monitoring in many centers, although with some reproducibility issues and interpretation difficulties. Confirmed abnormalities in these traditional biomarkers raise the suspicion for rejection and guide the indication for graft biopsy, which is still considered the gold standard for rejection monitoring. Rapidly evolving new "omic" technologies have led to the identification of several novel biomarkers, which may change the landscape of transplant monitoring should their potential be confirmed. Among them, urinary chemokines and measurement of cell-free DNA of donor origin are perhaps the most promising. However, at the moment, these approaches remain highly expensive and cost-prohibitive in most settings, with limited clinical applicability; approachable costs upon technology investments would speed their integration. In addition, transcriptomics, metabolomics, proteomics, and the study of blood and urinary extracellular vesicles have the potential for early identification of subclinical rejection with high sensitivity and specificity, good reproducibility, and for gaining predictive value in an affordable cost setting. In the near future, information derived from these new biomarkers is expected to integrate traditional tools in routine use, allowing identification of rejection prior to clinical manifestations and timely therapeutic intervention. This review will discuss traditional, novel, and invasive and non-invasive biomarkers, underlining their strengths, limitations, and present or future applications in children.

Contemporary Biomarkers for Renal Transplantation: A Narrative Overview

Renal transplantation (RT) is the preferred treatment for end-stage renal disease. However, clinical challenges persist, i.e., early detection of graft dysfunction, timely identification of rejection episodes, personalization of immunosuppressive therapy, and prediction of long-term graft survival. Biomarkers have emerged as valuable tools to address these challenges and revolutionize RT patient care. Our review synthesizes the existing scientific literature to highlight promising biomarkers, their biological characteristics, and their potential roles in enhancing clinical decision-making and patient outcomes. Emerging non-invasive biomarkers seemingly provide valuable insights into the immunopathology of nephron injury and allograft rejection. Moreover, we analyzed biomarkers with intra-nephron specificities, i.e., glomerular vs. tubular (proximal vs. distal), which can localize an injury in different nephron areas. Additionally, this paper provides a comprehensive analysis of the potential clinical applications of biomarkers in the prediction, detection, differential diagnosis and assessment of post-RT non-surgical allograft complications. Lastly, we focus on the pursuit of immune tolerance biomarkers, which aims to reclassify transplant recipients based on immune risk thresholds, guide personalized immunosuppression strategies, and ultimately identify patients for whom immunosuppression may safely be reduced. Further research, validation, standardization, and prospective studies are necessary to fully harness the clinical utility of RT biomarkers and guide the development of targeted therapies.

Nomograms for Predicting the Incidence of Late-Onset Acute Cellular Rejection in Patients After Pediatric Liver Transplantation

BACKGROUND

Late-onset acute cellular rejection (LACR) is a special type of acute rejection (AR) only rarely studied after pediatric liver transplantation (pLT). Our study aimed to explore the influencing factors of LACR after pLT and establish a nomogram to provide an individualized prediction of LACR after pLT.

MATERIALS AND METHODS

Data from 640 children who underwent pLT at Tianjin First Central Hospital from January 2016 to December 2019 were collected as part of this retrospective study. The nomogram was then established through the results of the multivariable analysis.

RESULTS

Forty-one patients experienced LACR > 1 ≤ 2 years after pLT. Cold ischemia time, donor-specific antibodies (DSAs), and tacrolimus concentration were independent influencing factors, and a nomogram was established with an AUC value of 0.834 (95% confidence interval, 0.755-0.912). Ten-fold cross-validation showed that the accuracy of the nomogram was about 76%. Sixty-three patients experienced LACR > 2 years after pLT. Child-Pugh grade, cold ischemic time, DSAs, early acute cellular rejection, and tacrolimus concentration were independent influencing factors, and a nomogram was established with an AUC value of 0.827 (95% confidence interval, 0.774-0.881). Ten-fold cross-validation showed that the accuracy of the nomogram was about 80.9%.

CONCLUSION

We established nomograms to predict the incidence of LACR > 1 ≤ 2 and > 2 years after pLT, respectively. The verification results showed that nomograms had good accuracy and clinical practicability.

Predicting acute rejection in children, adolescents, and young adults with a kidney transplant by assessing barriers to taking medication

BACKGROUND

Nonadherence to immunosuppression is common among pediatric, adolescent, and young adult kidney transplant recipients and a leading cause of graft loss. Assessing barriers to medication adherence in clinical practice may identify patients at risk for rejection and provide therapeutic targets.

METHODS

Kidney transplant patients and/or their caregivers were assessed for 14 barriers to medication adherence using the barriers assessment tool. We compared rejection rates between patients with at least one reported adherence barrier to those without reported adherence barriers using a Kaplan-Meier estimator and Cox proportional hazard models to adjust for other mediators of acute rejection at 2 years following barriers assessment.

RESULTS

Ninety-eight patients were assessed for barriers to adherence. Over the 2-year observation period, 22 patients developed biopsy-proven acute rejection (BPAR). Kaplan-Meier estimates show that patients with an identified barrier to adherence were more likely to have BPAR (p = 0.02) than patients without an identified barrier in the 24 months following barriers assessment. The median time to rejection for patients who experienced acute rejection was 175.5 days (IQR 63-276 days) from the time of barriers assessment. An identified barrier to adherence remained the only statistically significant predictor of BPAR with Cox modeling (HR 2.6, p = 0.04), after accounting for age, sex, and race.

CONCLUSIONS

Pediatric and adolescent kidney transplant recipients with identified adherence barriers are at increased risk for acute rejection. Barriers to adherence provide a potentially modifiable therapeutic target that can be assessed in clinic to guide targeted interventions.

Acute rejection in pediatric renal transplantation: Retrospective study of epidemiology, risk factors, and impact on renal function

AR is a major relevant and challenging topic in pediatric kidney transplantation. Our objective was to evaluate cumulative incidence of AR in pediatric kidney transplant patient, risk factors for this outcome, and impact on allograft function and survival. A retrospective cohort including pediatric patients that underwent kidney transplantation between 2011 and 2015 was designed. Risk factors for AR were tested by competing risk analysis. To estimate its impact, graft survival and difference in GFR were evaluated. Two hundred thirty patients were included. As a whole, the incidence of AR episodes was 0.16 (95% CI = 0.12-0.20) per person-year of follow-up. And cumulative incidence of AR was 23% in 1 year and 39% in 5 years. Risk factors for AR were number of MM (SHR 1.36 CI 1.14-1.63 P = .001); ISS with CSA, PRED, and AZA (SHR 2.22 CI 1.14-4.33 P = .018); DGF (SHR 2.49 CI 1.57-3.93 P < .001); CMV infection (SHR 5.52 CI 2.27-11.0 P < .001); and poor adherence (SHR 2.28 CI 1.70-4.66 P < .001). Death-censored graft survival in 1 and 5 years was 92.5% and 72.1%. Risk factors for graft loss were number of MM (HR 1.51 CI 1.07-2.13 P = .01), >12 years (HR 2.66 CI 1.07-6.59 P = .03), and PRA 1%-50% (HR 2.67 CI 1.24-5.73 P = .01). Although occurrence of AR did not influence 5-year graft survival, it negatively impacted GFR. AR was frequent in patients assessed and associated with number of MM, ISS regimen, DGF, CMV infection, and poor adherence, and had deleterious effect on GFR.

Association of graft survival with tacrolimus exposure and late intra-patient tacrolimus variability in pediatric and young adult renal transplant recipients-an international CTS registry analysis

Adolescent and young adult age is a high-risk window with an alarmingly increased likelihood of premature kidney graft loss due to immunological rejection. Using the large database of the Collaborative Transplant Study, we analyzed whether a more intense and less variable exposure to tacrolimus could counteract this young age-related enhanced immunoreactivity. Kidney graft recipients aged 12-23 years (n = 964) with a 1-year tacrolimus trough level between 4.0 and 10.9 ng/ml had a 5-year graft survival rate of 85.1%, significantly better than the poor 66.1% rate in patients with a trough level below 4.0 ng/ml who showed a 2.38-fold increased risk of graft loss in the multivariable analysis (P < 0.001). This association was not apparent in young children aged 0-11 years (n = 455) and less pronounced in adults aged 24-34 years (n = 1466). However, an intra-patient variability of tacrolimus (IPV) trough level ≥1.5 at post-transplant years 1 and 2 was associated with an increased graft loss risk in both 12- to 23-year-old and 0- to 11-year-old recipients (P < 0.001 and P = 0.045). Patients with high IPV made up as many as 30% of kidney graft recipients, indicating that a more intense and less variable exposure to tacrolimus could improve graft survival strongly in this high-risk group.

Circulating de novo Donor Specific Antibodies and Carotid Intima-media Thickness in Pediatric Kidney Transplant Recipients, A Pilot Study

Background: The presence of circulating de novo donor specific anti-HLA antibodies (dnDSA) has been implicated in an immune-mediated form of accelerated systemic arteriosclerosis in adult heart and kidney transplant recipients, however this has not been previously investigated in pediatric kidney transplant recipients. Carotid intima-media thickness (CIMT) is a reliable method for detection of arteriosclerosis. We hypothesized that children who develop dnDSA after kidney transplant would have increased CIMT compared with those who remain dnDSA negative. Methods: A prospective, controlled pilot cohort study of 38 transplant patients and 20 healthy controls was conducted to investigate the association between CIMT and development of dnDSA after kidney transplant. CIMT, anthropometrics, blood pressure and lipid panel were measured at 1, 18, and 30 months post-transplant. DSA was checked at 6, 12, 18, 24 and 30 months post-transplant. CIMT of DSA positive transplant recipients was compared to DSA negative and controls. Results: Of the 38 transplant recipients, 7 patients developed dnDSA by 18-30 months post-transplant. Among 5 dnDSA positive patients who did not receive treatment for DSA prior to CIMT measurement (n=6 observations), the median CIMT was 0.505 mm (95% CI 0.454-0.560 mm) at 18-30 months post-transplant, compared to 0.455 mm (95% CI 0.440-0.470) in DSA negative transplant recipients (n = 54 observations of 30 patients) and 0.450 mm (95% CI 0.436-0.460) in the healthy controls (20 observations of 20 patients). Presence of dnDSA was independently associated with a 7.8% increase in CIMT compared to those without dnDSA (p=0.006), after adjusting for race, hypertension, dyslipidemia, and abdominal obesity. Conclusions: Development of dnDSA was associated with increased CIMT, an indicator of arteriosclerosis, in a cohort of dnDSA positive pediatric kidney transplant recipients. The association between dnDSA and CIMT was independent of traditional CV risk factors, including hypertension, dyslipidemia, and abdominal obesity.

Defining a threshold for tacrolimus intra-patient variability associated with late acute cellular rejection in paediatric kidney transplant recipients

BACKGROUND

Late acute cellular rejection (LACR) is associated with poorer graft outcomes and non-adherence. Non-adherence to tacrolimus can be indirectly assessed by the intra-patient variability (IPV) of tacrolimus trough levels. The threshold of IPV associated with rejection is not known.

METHODS

We conducted a case-control study comparing 25 patients with biopsy-proven LACR against 25 stable controls matched for age group, primary diagnosis and time post-transplant. IPV was calculated using coefficient of variance (CV) and mean absolute deviation (MAD) using tacrolimus levels in the preceding 12 months. We also assessed the percentage time for tacrolimus levels < 4 μg/L (Tac < 4) and the concentration/weight-adjusted dose (C/D) ratio as a proxy marker of tacrolimus metaboliser status.

RESULTS

LACR patients had higher CV (median, IQR 44%, 36-61% v. 24%, 19-35%, p < 0.0001) and higher MAD (33%, 25-48% v. 19%, 15-26%, p < 0.0001). The MAD was less affected by outlying tacrolimus results. Receiver operating curve analysis of the MAD resulted in a sensitivity of 76% and specificity of 76% at a threshold of 26% (AUC 0.85, p < 0.05). LACR patients had more Tac < 4 (50% v. 26%, p < 0.05). There was no difference in C/D suggesting that good IPV can be maintained in fast metabolisers. Patients with LACR had significantly increased creatinine at 12-month follow-up despite treatment (108 v. 5 umol/L increase from baseline) and four patients lost their allograft.

CONCLUSIONS

Monitoring of tacrolimus IPV using the MAD may be a clinical marker for LACR. A threshold IPV of 26% can potentially be used as a therapeutic target pending further validation studies.

Assessment and Treatment of Nonadherence in Transplant Recipients

Stable intake of an immunosuppressant medication regimen is essential for posttransplant survival in the vast majority of cases. And yet, many patients are nonadherent (do not take their medications as prescribed), and suffer consequences ranging from rejection to morbidity and mortality. We review the evidence related to monitoring of adherence to medications, and intervention strategies. Our aim is to provide a baseline from which readers may approach behavioral aspects of posttransplant care. This review may also help readers in designing clinical programs for routine monitoring of adherence, and inform the choice of intervention when adherence falls below a certain threshold.

Results of early treatment for de novo donor-specific antibodies in pediatric kidney transplant recipients in a cross-sectional and longitudinal cohort

The development of dnDSA anti-HLA antibodies has been shown to be a significant risk factor for graft failure. In 2008, we instituted a routine protocol of standardized monitoring and treatment of dnDSA in pediatric kidney transplant recipients. Of 67 first-time pediatric kidney transplant recipients, 26 (38%) developed dnDSA after 1.36 (IQ 1-2.14) years. Coefficient of variance of tacrolimus, a surrogate marker of non-adherence, was found to be the single most important risk factor for dnDSA development. Overall, there was a significant reduction in dnDSA with treatment in 19 (76%) children. No difference in graft survival and estimated glomerular filtration rate was noted between dnDSA negative and those treated for dnDSA. There was an increased risk of hospitalization in those treated for dnDSA. This study suggests that early detection and treatment of dnDSA can help to prevent graft failure and preserve graft function in the short term. Future studies and longer follow-up are needed to fully elucidate the effect of early detection and treatment of dnDSA in pediatric kidney transplant recipients.

Induction therapy of basiliximab versus antithymocyte globulin in renal allograft: a systematic review and meta-analysis

OBJECTIVE

The aim of this meta-analysis was to evaluate the efficacy of basiliximab versus antithymocyte globulin for induction therapy in renal allograft.

METHODS

Medline (PubMed), Embase, Ovid, Cochrane, and the Chinese Biomedical Literature databases were searched to identify prospective randomized controlled trials that compared basiliximab with antithymocyte globulin (ATG) for induction therapy in renal transplantation. RevMan 5.1 software and Stat Manager V4.1 software were used for the meta-analysis.

RESULTS

Eight RCTs were included, including a total of 1153 patients. Of these, 547 (47%) had received basiliximab, and 606 (53%) had received ATG. The pooled results revealed that the basiliximab had a lower rate of neoplasm compared with ATG [odds ratio (OR) 0.26; 95% confidence interval (CI) 0.08-0.78; P = 0.02]. There were no significant differences between the two drugs regarding 1-year acute rejection rate (OR 1.32; 95% CI 0.93-1.87; P = 0.13), 1-year graft survival rate (OR 0.73; 95% CI 0.45-1.18; P = 0.20), 1-year patient survival rate (OR 0.52; 95% CI 0.27-1.02; P = 0.06), 1-year infection rate (OR 0.90; 95% CI 0.48-1.68; P = 0.73).

CONCLUSION

Induction therapy of basiliximab has similar short-time effects on the recipients in renal transplantation compared with that of ATG. However, regarding the long-term effect, as represented by the rate of neoplasm, basiliximab has a significant advantage.

Predictive Factors of Acute Rejection in Low Immunologic Risk Kidney Transplant Recipients Receiving Basiliximab

INTRODUCTION

The optimal immunosuppressive induction therapy in kidney transplant recipients with low immunologic risk of acute rejection (AR) is still controversial. The use of basiliximab (BSX) has led to a significant decrease of AR with a low side effect profile.

OBJECTIVE

This study sought to evaluate predictive risk factors for AR in low immunologic risk patients subjected to immunosuppressive induction therapy with BSX.

METHODS

We reviewed all low immunologic risk patients (panel reactive antibody [PRA] level <50%, who had undergone a first deceased-donor transplant) subjected to immunosuppressive induction therapy with BSX, calcineurin inhibitor, mycophenolate mofetil, and prednisolone (n = 346). AR was defined as any rejection occurring until 12 months posttransplantation. Predictive risk factors for AR were evaluated by logistic regression and, to find the best cut-off of PRA related to a higher incidence of AR, receiver-operator characteristic (ROC) curve analysis was performed.

RESULTS

The rate of AR was 7.8%. Multivariate logistic regression analysis identified age at the time of transplantation (P = .040) and PRA level (P = .001) as independent risk factors for AR. ROC curve analysis confirmed that PRA >10% was related to an increased incidence of AR (19.2% vs 6.0%, P = .005).

CONCLUSIONS

A higher incidence of AR was observed in low immunologic risk kidney transplant patients with a PRA level >10%. These data support the use of more intensive immunosuppressive induction therapy in patients with low immunologic risk and a PRA level >10%.

Gene Expression in Biopsies of Acute Rejection and Interstitial Fibrosis/Tubular Atrophy Reveals Highly Shared Mechanisms That Correlate With Worse Long-Term Outcomes

Interstitial fibrosis and tubular atrophy (IFTA) is found in approximately 25% of 1-year biopsies posttransplant. It is known that IFTA correlates with decreased graft survival when histological evidence of inflammation is present. Identifying the mechanistic etiology of IFTA is important to understanding why long-term graft survival has not changed as expected despite improved immunosuppression and dramatically reduced rates of clinical acute rejection (AR) (Services UDoHaH. http://www.ustransplant.org/annual_reports/current/509a_ki.htm). Gene expression profiles of 234 graft biopsy samples were obtained with matching clinical and outcome data. Eighty-one IFTA biopsies were divided into subphenotypes by degree of histological inflammation: IFTA with AR, IFTA with inflammation, and IFTA without inflammation. Samples with AR (n = 54) and normally functioning transplants (TX; n = 99) were used in comparisons. A novel analysis using gene coexpression networks revealed that all IFTA phenotypes were strongly enriched for dysregulated gene pathways and these were shared with the biopsy profiles of AR, including IFTA samples without histological evidence of inflammation. Thus, by molecular profiling we demonstrate that most IFTA samples have ongoing immune-mediated injury or chronic rejection that is more sensitively detected by gene expression profiling. These molecular biopsy profiles correlated with future graft loss in IFTA samples without inflammation.

Characteristics of Children Reported to Child Protective Services for Medical Neglect

OBJECTIVES

Medical neglect can have serious consequences. There is little evidence base to guide medical neglect management and research. Our objective was to describe a group of children reported to child protective services (CPS) for medical neglect to define this population as well as identify prevention and intervention approaches.

METHODS

This was a retrospective descriptive study of all patients at a pediatric hospital reported to CPS for medical neglect over a 6-year period. Data about health, health care, CPS involvement, and social history were obtained through medical record review.

RESULTS

Of the 154 patients reported for medical neglect, 140 (91%) had chronic illness. The most common diagnoses were type 1 diabetes, organ transplantation, and prematurity-related conditions. Most patients (83%) were black or Hispanic and 90% were publically insured. More than half of patients (54%) had >1 CPS report during the study period. Almost all patients (88%) returned to the hospital for care subsequent to the medical neglect report. Risk factors for child maltreatment, family stressors in the year preceding the report, and practical barriers to care were documented in more than two-thirds of patients.

CONCLUSIONS

Overall, children reported for medical neglect have serious chronic medical conditions. There is need and opportunity for improved interventions. Avenues for future study include interventions tailored to the underlying diagnosis, racial/ethnic disparities, effectiveness of CPS interventions, and targeted prevention for at-risk families with medically complex children.

Minimum mycophenolic acid levels are associated with donor-specific antibody formation

Although de novo DSA are associated with inferior graft survival, there are no effective strategies to prevent their formation. Underexposure to MPA (prodrug: MMF) also contributes to rejection rates early after transplantation, but the effect of this phenomenon on the formation of DSA long-term post-transplantation is unknown. Data are expressed as mean (standard deviation). All available data from 32 renal transplant recipients (age at transplantation 7.5 [4.5] yr) on tacrolimus and MPA immunosuppression with an average follow-up of 9.4 (s.d. 4.6) yr were analyzed. DSA were measured using the Luminex assay (>500 MFI was considered DSA-positive). Tacrolimus and MPA levels were measured with the Abbot Tacro II and EMIT assay, respectively. Among 1964 MPA and 3462 tacrolimus trough levels, the average MPA trough level was 3.2 (1.5) mg/L and the average tacrolimus level was 6.7 (2.8) ng/mL. At last follow-up, only 5/32 patients had undetectable DSA, with 5/32 having no class I antibodies and 6/32 having no class II antibodies. DSA formation was associated with a lower minimum MPA trough level (0.27 [0.23] vs. 0.47 [0.18] mg) and cystatin C eGFR (48 [21] vs. 70 [23] mL/min/1.73 m(2)) for class I DSA formers. The average eGFR of patients without class I DSA was 70 (23) mL/min/1.73 m(2), whereas the average eGFR of patients with class I DSA was 48 (21) mL/min/1.73 m(2) (p = 0.0071). MPA trough levels <1.3 mg/L long-term post-transplantation are associated with the formation of DSA. The association between the formation of DSA and minimum MPA exposure may support a strategy for preventing the formation of DSA.

Donor-specific anti-HLA antibodies in pediatric renal transplant recipients with creeping creatinine: Prevalence, histological correlations, and impact on patient and graft survival

Donor-specific anti-HLA antibodies (DSA) causing CAMR are responsible for a high proportion of long-term graft failures after RTX. We studied the prevalence of DSA in RTX children biopsied for creeping Cr, its relationship with NA, and patient and graft survival according to histopathology. Between 2008 and 2013, 92 children were biopsied at a median of 38 months post-RTX. At biopsy, the prevalence of DSA was 49% and C4d 70%. NA rate was 45%, higher in adolescents (60%). Most frequent diagnoses were CAMR (72%) and interstitial fibrosis with tubular atrophy (IFTA) (28%). Forty-five of 66 patients with CAMR (68%) had detectable DSA. Twenty-one DSA-negative patients with CAMR had histological damage (IFTA + C4d positivity). C4d was detected in 64 of 66 biopsies with CAMR. Recipients with IFTA alone had neither C4d, nor detectable DSA, and were adherent. Graft survival at five yr was 89% in patients with CAMR, 79% in those with CAMR + TCMR Banff I, 33% in those with CAMR + TCMR Banff II, and 96% in those with IFTA. ABMR and complement activation were frequent in children biopsied for creeping Cr. Recipients with DSA were more likely to be non-adherent and have CAMR or CAMR + TCMR and worse graft survival.