ABO-incompatible heart transplantation can be performed safely during infancy before the onset of isohemagglutinin production; this technique thus contributes to a marked reduction in mortality among infants on the waiting list.

Although over 50 years have passed since its first laboratory description, intentional induction of immune tolerance to foreign antigens has remained an elusive clinical goal. We previously reported that the requirement for ABO compatibility in heart transplantation is not applicable to infants. Here, we show that ABO-incompatible heart transplantation during infancy results in development of B-cell tolerance to donor blood group A and B antigens. This mimics animal models of neonatal tolerance and indicates that the human infant is susceptible to intentional tolerance induction. Tolerance in this setting occurs by elimination of donor-reactive B lymphocytes and may be dependent upon persistence of some degree of antigen expression. These findings suggest that intentional exposure to nonself A and B antigens may prolong the window of opportunity for ABO-incompatible transplantation, and have profound implications for clinical research on tolerance induction to T-independent antigens relevant to xenotransplantation.

Late graft rejection impairs the long-term function of organ transplants in children. Previous studies suggest patients with wide variation in tacrolimus levels may have higher rates of late kidney and liver graft rejection. The reproducibility of this finding and impact on graft and recipient survival have not been reported. We investigated factors associated with late rejection > 6 months post-transplant in 144 heart, kidney, liver, and lung transplant recipients (ages 8-18, ≥ 1-yr survivors, receiving tacrolimus-based immunosuppression), comparing late rejectors (n = 61, 42%) to non-rejectors (no rejection > 6 months); groups had similar mean tacrolimus concentrations ≤ 6 months post-transplant. For all organ types, increased standard deviation in intrapatient tacrolimus blood levels was an independent risk factor for late rejection (OR 1.6 [CI 1.1-2.1]; p = 0.02). Each 1-point increase in s.d. > 2 of tacrolimus level > 6 months post-transplant associated with 1.58 increase in hazard of graft loss (p = 0.003). Graft survival (conditional on one-yr survival) was significantly better for those with s.d. < 2 at > 6 months post-transplant: 98% at three and five yr, versus 88%, 70%, at three and five yr, in patients with s.d. > 2 (p = 0.003). In conclusion, high s.d. in serial tacrolimus concentrations associated with increased risk of late rejection and graft loss in pediatric organ transplant recipients, providing opportunities for screening and interventions.

Kidney transplantation is an optimal therapy for pediatric patients with end-stage kidney disease. This pilot study sought to examine multidimensional QOL outcomes after kidney transplant using VAQOL and General Health, the PedsQL 4.0, PedsQL End Stage Renal Disease Module, and Impact on Family Module. Sample included 12 adolescents aged 13-18 yr and their parent; three children aged eight to 12 yr and their parent; and six parents of children aged two to seven yr. All were 73 months post transplant. The median age at transplant was 9.3 yr and median time since transplant was 3.2 yr. VAQOL mean was 7.7/10 (child report) and 7.3/10 (parent report); the mean general health was 7.4/10. High levels of fatigue (> or =5/10) were reported in 43%. PedsQL subscale mean values were lower than healthy reference scores. PedsQL Renal Module demonstrated great concern with physical appearance and physical symptoms (thirst and headaches), difficulty with peer and family interaction, and school disruption. Low scores on parental emotional function depict the negative impact of transplant on family functioning. Discordance exists between child and parental reports of QOL. Prospective studies are needed to explore multidimensional QOL to improve long-term outcomes after pediatric kidney transplant.

A strategy to accept ABO-incompatible donor hearts for infant transplantation significantly improves the likelihood of transplantation and reduces waiting list mortality while not adversely altering outcomes after transplantation.

Background— There is an elevated risk for poor outcomes after heart transplant (HTx) in patients sensitized to human leukocyte antigens including graft dysfunction, acute cellular and antibody-mediated (AMR) rejection, and cardiac allograft vasculopathy. We report our experience with human leukocyte antigens–sensitized pediatric HTx recipients. Methods and Results— We identified pediatric HTx patients with elevated pre-HTx Panel Reactive Antibody (Class I/II; >10%), or a positive T- or B-cell crossmatch. Thirteen patients met criteria (5 female, 39%). The median age at HTx was 7 months (3.5 months to 15.5 years). Nine were infants who had prior palliation for congenital heart disease. Four were older patients (median 7.3 years; 4.8 to 15.5 years): 2 had congenital heart disease (Fontan), 2 were re-HTx. B-cell therapies were used in all patients, guided by assessment of CD19+ and CD20+ cells. Immunosuppression included thymoglobulin induction, and tacrolimus, mycophenolate mofetil, and steroids. Daily plasmapheresis ± intravenous immunoglobulin G was used if there was a positive crossmatch on day 1, with a gradual, biopsy-guided weaning schedule. Rituximab was used when AMR was detected on biopsy: more recently (n=3), used empirically perioperatively. AMR was confirmed in 9 patients within median 0.9 months post-HTx. Seven had early acute cellular rejection (≥ ISHLT Grade 2 R) with no hemodynamic compromise or graft dysfunction. There were 4 deaths post-HTx (range, 11 days to 9 months). The median follow-up of 9 survivors was 1.7 years (0.3 to 3.7 years). Of 7 patients >6 months post-HTx, no AMR or cardiac allograft vasculopathy was observed at a mean of 1.9+1.1 years post-HTx and no cardiac allograft vasculopathy. Conclusions— Despite aggressive management, acute cellular rejection and AMR occurred frequently early post-HTx. An algorithm of B cell–directed strategies can be effective in managing these patients with reasonable intermediate-term outcomes.

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