There are limited data on the impact of COVID‐19 in children with a kidney transplant (KT). We conducted a prospective cohort study through the Improving Renal Outcomes Collaborative (IROC) to collect clinical outcome data about COVID‐19 in pediatric KT patients. Twenty‐two IROC centers that care for 2732 patients submitted testing and outcomes data for 281 patients tested for SARS‐CoV‐2 by PCR. Testing indications included symptoms and/or potential exposures to COVID‐19 ( N = 134, 47.7%) and/or testing per hospital policy ( N = 154, 54.8%). Overall, 24 (8.5%) patients tested positive, of which 15 (63%) were symptomatic. Of the COVID‐19‐positive patients, 16 were managed as outpatients, six received non‐ICU inpatient care and two were admitted to the ICU. There were no episodes of respiratory failure, allograft loss, or death associated with COVID‐19. To estimate incidence, subanalysis was performed for 13 centers that care for 1686 patients that submitted all negative and positive COVID‐19 results. Of the 229 tested patients at these 13 centers, 10 (5 asymptomatic) patients tested positive, yielding an overall incidence of 0.6% and an incidence among tested patients of 4.4%. Pediatric KT patients in the United States had a low estimated incidence of COVID‐19 disease and excellent short‐term outcomes.

The development of EBV infection and PTLD is normally associated with a high EBV viral load in peripheral blood. Observations have previously identified existence of a CHL carrier state that demonstrated variable outcomes based upon the organ which was transplanted. Data defining the incidence and outcome of CHL in pediatric KTx are not well described. The charts of children undergoing isolated KTx at Children's Hospital of Pittsburgh between January 2000 and December 2014 were retrospectively reviewed. EBV loads in the peripheral blood were routinely measured as part of surveillance protocols at our center. CHL was defined as the presence of high load for >50% of samples for ≥6 months. PTLD was defined histologically using WHO definitions. Of 188 isolated KTx recipients, we identified a total of 16 (8%) children who developed CHL carrier state. No patient developed EBV-driven late-onset PTLD. Age at the time of KTx was significantly lower in the CHL group (median 3.9 years, interquartile range: IQR 2.9-6.6, P = .0004). Children in the CHL group were more likely to be EBV-seronegative prior to KTx (94%, 15/16), compared to the UVL and LVL groups (55% and 50%, respectively, P < .002). The median duration of CHL carrier state was 20 months (IQR 10.7-35.8). Fifteen of the 16 CHL carriers experienced spontaneous resolution of CHL carrier state. Children in the CHL group were younger at the time of primary EBV infection (P = .023). Finally, antiviral medication was not effective in either preventing or decreasing the EBV viral load in blood (P = .84). Overall incidence of late-onset PTLD is very low compared to heart and intestinal transplant, even though KTx recipients can develop CHL carrier state. The CHL carriers in KTx recipients were EBV-seronegative prior to transplant and were younger both at the time of KTx and at the time of primary EBV infection compared to those in the UVL and HVL groups. Antivirals did not prevent EBV infection or decrease EBV viral loads.

BackgroundAlthough antibody-mediated rejection (ABMR) has been long recognized as a leading cause of allograft failure after kidney transplantation, the cellular and molecular processes underlying the induction of deleterious donor-specific antibody (DSA) responses remain poorly understood.MethodsUsing high-dimensional flow cytometry, in vitro assays, and RNA sequencing, we concomitantly investigated the role of T follicular helper (TFH) cells and B cells during ABMR in 105 kidney transplant recipients.ResultsThere were 54 patients without DSAs; of those with DSAs, ABMR emerged in 20 patients, but not in 31 patients. We identified proliferating populations of circulating TFH cells and activated B cells emerging in blood of patients undergoing ABMR. Although these circulating TFH cells comprised heterogeneous phenotypes, they were dominated by activated (ICOS+PD-1+) and early memory precursor (CCR7+CD127+) subsets, and were enriched for the transcription factors IRF4 and c-Maf. These circulating TFH cells produced large amounts of IL-21 upon stimulation with donor antigen and induced B cells to differentiate into antibody-secreting cells that produced DSAs. Combined analysis of the matched circulating TFH cell and activated B cell RNA-sequencing profiles identified highly coordinated transcriptional programs in circulating TFH cells and B cells among patients with ABMR, which markedly differed from those of patients who did not develop DSAs or ABMR. The timing of expansion of the distinctive circulating TFH cells and activated B cells paralleled emergence of DSAs in blood, and their magnitude was predictive of IgG3 DSA generation, more severe allograft injury, and higher rate of allograft loss.ConclusionsPatients undergoing ABMR may benefit from monitoring and therapeutic targeting of TFH cell–B cell interactions.

No abstract