Recurrence of focal segmental glomerulosclerosis after kidney transplantation: strategies and outcome:

A Systematic Review and Meta-Analysis of the Rate and Risk Factors for Post-transplant Disease Recurrence in Children With Steroid Resistant Nephrotic Syndrome

Introduction

Posttransplant disease recurrence is a feared and severe complication in children with steroid resistant nephrotic syndrome (SRNS), but little is known about its incidence. Recent data suggest relapse is exceptional in patients with genetic SRNS, and initial steroid sensitivity may represent a risk factor for recurrence.

Methods

Systematic review and meta-analysis were performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to describe the post-transplant relapse rate among children with SRNS; as well as the association between recurrence and all potential risk factors, including the presence of causative genetic mutations, initial steroid sensitivity, underlying histology, and gender. The inclusion criteria were as follows: (i) children with SRNS who are undergoing kidney transplant, (ii) available data on post-transplant recurrence, (iii) no patient selection according to the underlying histology, (iv) available data on genetic testing, and (v) prospective or retrospective cohort design.

Results

Of the 5818 records identified, 8 studies including 581 children with SRNS met the inclusion criteria. Overall posttransplant recurrence rate was 39% (95% confidence interval [CI] 34%-44%). No genetic patient relapsed, whereas the recurrence rate in patients with no causative genetic mutation identified was 61% (95% CI 53%-69%). Children with initial steroid sensitivity were at a higher risk for recurrence with a 1.91 relative risk (RR) (95% CI 1.48-2.46) compared with those with primary SRNS (PSRNS). Gender and histology did not significantly affect relapse rate.

Conclusion

Post-transplant recurrence is a common event in children with idiopathic non-genetic SRNS, complicating the clinical course in over 60% of patients. The presence of a causative genetic mutation virtually excludes a recurrence. Initial steroid sensitivity is the only other significant risk factor, doubling the risk of relapse.

Long-term plasmapheresis therapy in the management of focal segmental glomerulosclerosis recurrence after kidney transplantation

The recurrence of primary focal segmental glomerulosclerosis (FSGS) after kidney transplantation (KT) appears in 30 % of the recipients. Sometimes it can cause the loss of the allograft. Although many treatments for this condition have been reported, 20 %-40 % of the affected patients are refractory or presents frequents relapses. In this paper we describe the evolution of three recipients treated with long-term plasmapheresis therapy after a recurrence of FSGS with a bad or incomplete response to other treatments. Although our findings require confirmation, long-term plasmapheresis could be a therapeutic option for this condition.

Generating Kidney from Stem Cells

Human kidney tissue can now be generated via the directed differentiation of human pluripotent stem cells. This advance is anticipated to facilitate the modeling of human kidney diseases, provide platforms for nephrotoxicity screening, enable cellular therapy, and potentially generate tissue for renal replacement. All such applications will rely upon the accuracy and reliability of the model and the capacity for stem cell-derived kidney tissue to recapitulate both normal and diseased states. In this review, we discuss the models available, how well they recapitulate the human kidney, and how far we are from application of these cells for use in cellular therapies.

Post-transplant recurrence of steroid resistant nephrotic syndrome in children: the Italian experience

Background

Steroid resistant nephrotic syndrome (SRNS) is a frequent cause of end stage renal disease in children and post-transplant disease recurrence is a major cause of graft loss.

Methods

We identified all children with SRNS who underwent renal transplantation in Italy, between 2005 and 2017. Data were retrospectively collected for the presence of a causative gene mutation, sex, histology, duration of pre-transplant dialysis, age at onset and transplant, HLA matching, recurrence, therapy for recurrence, and graft survival.

Results

101 patients underwent a first and 22 a second renal transplant. After a median follow-up of 58.5 months, the disease recurred on the first renal transplant in 53.3% of patients with a non-genetic and none with a genetic SRNS. Age at transplant > 9 years and the presence of at least one HLA-AB match were independent risk factors for recurrence. Duration of dialysis was longer in children with relapse, but did not reach statistical significance. Overall, 24% of patients lost the first graft, with recurrence representing the commonest cause. Among 22 patients who underwent a second transplant, 5 suffered of SRNS recurrence. SRNS relapsed in 5/9 (55%) patients with disease recurrence in their first transplant and 2 of them lost the second graft.

Conclusions

Absence of a causative mutation represents the major risk factor for post-transplant recurrence in children with SRNS, while transplant can be curative in genetic SRNS. A prolonged time spent on dialysis before transplantation has no protective effect on the risk of relapse and should not be encouraged. Retransplantation represents a second chance after graft loss for recurrence.

Plasma exchange in kidney transplantation: Still a valuable option for nephrotic syndrome recurrence

About 30% of the cases of steroid resistant nephrotic syndrome display a genetically determined disease and will not recur after kidney transplant; the other cases with fully or partially immunological pathogenesis display a high risk of post transplant recurrence. Although lots of studies were carried out in the last 50 years the pathogenetic mechanism is still obscure and the therapeutic approach mostly empirical. The cornerstones principles of the therapies are based on removal of a still undefined "permeability factor" through plasma-exchange or other apheresis techniques and inhibition of its synthesis by the immunological system through different drugs. The probability of successfully inducing persistant remission is nowadays around 30%through the different schemes experimented so far which mostly include plasmapheresis. Rituximab in the last years has significantly increased the efficacy of the treatments. Non responders are rapidly evolving to graft loss and will most probably recur also in subsequent transplant. Apart from genetics no other risk factors are predictive for recurrence.

Pediatric kidney transplantation

Since first performed in 1954, kidney transplantation has evolved as the preferred long-term treatment of children with end stage renal disease (ESRD). The etiology of chronic kidney disease (CKD) and ESRD in children is broad and can be quite complicated, necessitating a multidisciplinary team to adequately care for these patients and their myriad needs. Precise surgical techniques and modern protocols for immunosuppression provide excellent long-term patient and graft survival. This article reviews the many etiologies of renal failure in the pediatric population focusing on those most commonly leading to the need for kidney transplantation. The processes of evaluation, kidney transplantation, short-term and long-term complications, as well as long-term outcomes are also reviewed.

Successful Preemptive Kidney Transplantation With Rituximab Induction in a Patient With Focal Segmental Glomerulosclerosis and Massive Nephrotic Syndrome: A Case Report

Primary focal segmental glomerulosclerosis (FSGS) recurs in 30% of patients receiving their first kidney transplant and often leads to graft loss. In the past, patients with FSGS and overt nephrotic syndrome rarely underwent transplantation. Rituximab (RTX), an anti-CD20-specific monoclonal antibody, was previously reported to be a valuable option in treating relapsing FSGS after kidney transplantation. We report here the first successful kidney transplantation in a young patient with primary FSGS and massive nephrotic syndrome treated with RTX induction. The patient was a 24-year-old woman who had developed nephrotic syndrome at the age of 4 years. FSGS was confirmed by results of a kidney biopsy, with subsequent treatment with cyclosporine and steroids, without remission. She was referred for a preemptive, deceased donor kidney transplant despite proteinuria levels reaching ∼10 g/d. She received induction therapy with 2 doses of RTX (375 mg/m²) at days 0 and 7, followed by tacrolimus 5 mg twice daily, mycophenolate mofetil 500 mg twice daily, and steroids after transplantation. Immediate kidney graft function was observed, with no proteinuria since day 13 posttransplant. The pretransplant soluble urokinase-type plasminogen activator receptor serum concentration was 4550 pg/mL; it decreased to 2191 pg/mL at day 13 and was 2073 pg/mL at 6 months' posttransplant. Thirty months after transplantation, the patient's serum creatinine level is 0.8 mg/dL, and no proteinuria has been observed. Successful kidney transplantation in a patient with pretransplant overt nephrotic syndrome secondary to FSGS, using rituximab as an induction therapy, is possible. Further recommendations for transplantation in such patients, however, should be based on results from larger clinical trials.

Recent advances in understanding and treating nephrotic syndrome

Idiopathic nephrotic syndrome (INS) is one of the most common glomerular diseases in children and adults, and the central event is podocyte injury. INS is a heterogeneous disease, and treatment is largely empirical and in many cases unsuccessful, and steroids are the initial mainstay of therapy. Close to 70% of children with INS have some response to steroids and are labelled as steroid-‘sensitive’, and the rest as steroid-‘resistant’ (also termed focal segmental glomerulosclerosis), and single-gene mutations underlie a large proportion of the latter group. The burden of morbidity is enormous, both to patients with lifelong chronic disease and to health services, particularly in managing dialysis and transplantation. The target cell of nephrotic syndrome is the glomerular podocyte, and podocyte biology research has exploded over the last 15 years. Major advances in genetic and biological understanding now put clinicians and researchers at the threshold of a major reclassification of the disease and testing of targeted therapies both identified and novel. That potential is based on complete genetic analysis, deep clinical phenotyping, and the introduction of mechanism-derived biomarkers into clinical practice. INS can now be split off into those with a single-gene defect, of which currently at least 53 genes are known to be causative, and the others. Of the others, the majority are likely to be immune-mediated and caused by the presence of a still-unknown circulating factor or factors, and whether there is a third (or more) mechanistic group or groups remains to be discovered. Treatment is therefore now being refined towards separating out the monogenic cases to minimise immunosuppression and further understanding how best to stratify and appropriately direct immunosuppressive treatments within the immune group. Therapies directed specifically towards the target cell, the podocyte, are in their infancy but hold considerable promise for the near future.

Markers of disease and steroid responsiveness in paediatric idiopathic nephrotic syndrome: Whole-transcriptome sequencing of peripheral blood mononuclear cells

Objective

To identify markers of disease and steroid responsiveness in paediatric idiopathic nephrotic syndrome.

Methods

Whole-transcriptome sequencing was performed of peripheral blood mononuclear cells (PBMCs) from patients with NS. Differentially expressed genes (DEGs) were identified in patients with active NS vs those in remission, and those with steroid-sensitive NS (SSNS) vs steroid-resistant NS (SRNS).

Results

A total of 1065 DEGs were identified in patients with NS (n = 10) vs those in remission (n = 9). These DEGs correlated with cytokine and/or immune system signalling and the extracellular matrix. Comparisons between SSNS (n = 6) and SRNS (n = 4) identified 1890 DEGs. These markers of steroid responsiveness were enriched with genes related to the cell cycle, targets of microRNAs, and genes related to cytokines.

Conclusions

Meaningful DEGs were identified. Additional studies with larger numbers of patients will provide more comprehensive data.

Recurrence of Focal and Segmental Glomerulosclerosis After Transplantation

Focal segmental glomerulosclerosis, which is a common glomerular disorder, manifests clinically with a nephrotic syndrome and has a high propensity for recurrence after kidney transplantation. The pathophysiology is currently unknown, and podocytes appear to be the target of one or several circulating factor(s) that lead to the recurrence of proteinuria after kidney transplantation. Identifying these circulating factor(s) and cells involved in its synthesis remains elusive; however, recently, our research on podocyte cytoskeleton biology has opened a new era of treatment. This review will highlight recent progress in the physiopathology of focal segmental glomerulosclerosis recurrence after transplantation and its treatment.

Recurrence and Treatment after Renal Transplantation in Children with FSGS

Focal segmental glomerulosclerosis (FSGS) is a common cause of end-stage renal disease and a common pathologic diagnosis of idiopathic nephrotic syndrome (NS), especially in steroid-resistant cases. FSGS is known to recur after kidney transplantation, frequently followed by graft loss. However, not all patients with FSGS suffer from recurrence after kidney transplantation, and genetic and secondary FSGS have a negligible risk of recurrence. Furthermore, many cases of recurrence achieve remission with the current management of recurrence (intensive plasmapheresis/immunosuppression, including rituximab), and other promising agents are being evaluated. Therefore, a pathologic diagnosis of FSGS itself should not cause postponement of allograft kidney transplantation. For patients with a high risk of recurrence who presented with classical symptoms of NS, that is, severe edema, proteinuria, and hypoalbuminemia, close monitoring of proteinuria is necessary, followed by immediate, intensive treatment for recurrence.

Glomerular nestin expression: possible predictor of outcome of focal segmental glomerulosclerosis in children

BACKGROUND

A high prevalence of chronic kidney disease among children with focal segmental glomerulosclerosis (FSGS) leads to a permanent quest for good predictors of kidney dysfunction. Thus, we carried out a retrospective cohort study in order to examine known clinical and morphological predictors of adverse outcome, as well as to investigate glomerular nestin expression as a potential new early predictor of kidney dysfunction in children with FSGS. Relationships between nestin expression and clinical and morphological findings were also investigated.

METHODS

Among 649 renal biopsy samples, obtained from two children's hospitals, FSGS was diagnosed in 60 children. Thirty-eight patients, who met the criteria for this study, were followed up for 9.0 ± 5.2 years. Using Kaplan-Meier and Cox's regression analysis, potential clinical and morphological predictors were applied in two models of prediction: after disease onset and after the biopsy.

RESULTS

The present study revealed the following significant predictors of kidney dysfunction: patients' ages at disease onset, as well as age at biopsy, resistance to corticosteroid treatment, serum creatinine level, urine protein/creatinine ratio, vascular involvement, tubular atrophy, interstitial fibrosis, and decreased glomerular nestin expression.

CONCLUSIONS

The most important finding of our study is that nestin can be used as a potential new early morphological predictor of kidney dysfunction in childhood onset of FSGS, since nestin has been obviously decreased in both sclerotic and normal glomeruli seen by light microscopy.

Recurrence of idiopathic focal segmental glomerulosclerosis after kidney transplantation: experience of a Korean tertiary center

FSGS is the second most common cause of idiopathic NS in children. It often progresses to ESRD and commonly recurs after KT. To investigate the risk factors and the prognosis of recurrence in pediatric idiopathic FSGS in Korea, retrospective review of 43 KT in 38 children with idiopathic FSGS of last two decades was conducted. The patients presented at the median age of 5.1 yr (range 1.1-13.8 yr) and received KT 5.7 yr later (range 1.3-17.6 yr). FSGS recurred in 20 allografts immediately after transplantation, only in those who presented with NS but not in those who presented with AUA. The risk factors for recurrence were age of onset >5 yr and progression to ESRD within six yr but not sooner than 18 months. CR was achieved in 13 patients with FSGS recurrence and sustained in nine without subsequent relapse over a median of six and a half yr (0.6-20.7 yr). Pediatric idiopathic FSGS presenting with NS recurred in more than half of patients after transplantation. Interestingly, more rapid progression within less than 18 months did not predict recurrence. To identify high-risk patients of recurrence, an international cooperative study would be necessary.

Initial steroid sensitivity in children with steroid-resistant nephrotic syndrome predicts post-transplant recurrence

Of children with idiopathic nephrotic syndrome, 10%-20% fail to respond to steroids or develop secondary steroid resistance (termed initial steroid sensitivity) and the majority progress to transplantation. Although 30%-50% of these patients suffer disease recurrence after transplantation, with poor long-term outcome, no reliable indicator of recurrence has yet been identified. Notably, the incidence of recurrence after transplantation appears reduced in patients with steroid-resistant nephrotic syndrome (SRNS) due to monogenic disorders. We reviewed 150 transplanted patients with SRNS to identify biomarkers that consistently predict outcome of SRNS after transplantation. In all, 25 children had genetic or familial SRNS and did not experience post-transplant recurrence. We reviewed phenotypic factors, including initial steroid sensitivity, donor type, age, ethnicity, time to ESRD, and time on dialysis, in the remaining 125 children. Of these patients, 57 (45.6%) developed post-transplant recurrence; 26 of 28 (92.9%) patients with initial steroid sensitivity recurred after transplantation, whereas only 26 of 86 (30.2%) patients resistant from the outset recurred (odds ratio, 30; 95% confidence interval, 6.62 to 135.86; P<0.001). We were unable to determine recurrence in two patients (one with initial steroid sensitivity), and nine patients did not receive initial steroids. Our data show that initial steroid sensitivity is highly predictive of post-transplant disease recurrence in this pediatric patient population. Because a pathogenic circulating permeability factor in nephrotic syndrome remains to be confirmed, we propose initial steroid sensitivity as a surrogate marker for post-transplant recurrence.

Early posttransplant nephrotic range proteinuria as a presenting feature of minimal change disease and acute T cell-mediated rejection

Early-onset nephrotic range proteinuria is an extremely rare presentation of an acute rejection episode. Herein, we have reported a patient who developed nephrotic range proteinuria 7 days after receiving a renal allograft from his sister despite minor changes in serum creatinine levels. A kidney biopsy spcimen revealed a T cell-mediated acute rejection process concomitant with minimal change disease (MCD). Proteinuria and renal dysfunction improved dramatically in response to corticosteroids. The possibility of acute cellular rejection and coexisting MCD should be considered in patients with early posttransplantation nephrosis and normal serum creatinine levels. The coexistence of these entities provides support for the role of T cells in the pathogenesis of MCD.

Glomerular disease recurrence in the renal allograft: a hurdle but not a barrier for successful kidney transplantation

Almost all forms of primary as well as secondary glomerulonephritides may recur after renal transplantation. Recurrence of the original disease is now the third most common cause of late allograft loss. Nevertheless, in most cases it is difficult to assess the true impact of primary disease recurrence in the allograft; histological recurrence with mild features does not necessarily implicate clinically severe disease. Moreover it is often difficult to distinguish recurrent from de novo disease as in membranous glomerulopathy. Because recurrence occurs late, histological lesions of recurrent glomerulonephritis may be unmasked by chronic damage from other causes such as chronic rejection. Beside the difficulties to interpret renal histology due to the variety of allograft lesions, there are no well-established options to prevent clinically severe disease recurrence nor the therapeutic approaches to the problem. The purpose of this review was mainly to underline that almost all primary and secondary glomerulonephritides represent a contraindication to transplantation. For the majority of patients with end-stage renal disease due to glomerulonephritis, transplantation still represents the treatment of choice.

Case report: successful treatment of recurrent focal segmental glomerulosclerosis with a novel rituximab regimen

Focal segmental glomerulosclerosis (FSGS) is the cause of renal failure in more than 10% of pediatric patients undergoing renal transplantation. Recurrent FSGS is a major cause of pediatric allograft failure, with the risk increasing for patients undergoing retransplantation. Standard therapy for recurrent posttransplantation FSGS includes the use of intensive plasmapheresis (PP) in conjunction with cyclophosphamide or high-dose cyclosporine. However, many patients exhibit refractory disease, with rapid progression to allograft loss despite these interventions. Prior studies have reported conflicting data on the efficacy of adding rituximab therapy to the standard treatment regimen for recurrent posttransplantation FSGS. Here we present a successful therapeutic protocol with rapid elimination of PP after initiation of rituximab therapy for an adolescent patient with recurrent FSGS in the immediate postoperative period. The patient has maintained excellent allograft function through 12 months posttransplantation.

Recurrent focal segmental glomerulosclerosis: a discrete clinical entity

Focal segmental glomerulosclerosis refers to a set of particular histopathologic lesions in which steroid-resistant podocyte injury leads to patchy adhesions between the glomerular tuft and Bowman's capsule, followed by progressive glomerulosclerosis and proteinuric renal failure. Because of the nonspecific nature of this lesion, it has been difficult to classify the various forms of primary nephrotic syndrome in children. However, with the recognition of hereditary FSGS caused by mutations podocyte slit diaphragm genes, it is increasingly clear that the steroid-resistant form of FSGS that recurs in the renal allografts (R-FSGS) constitutes a distinct clinical entity. Capitalizing on recent studies in which patients have been screened for slit diaphragm gene mutations, this review focuses on the natural history and pathogenesis of R-FSGS.

Impact of recurrent glomerulonephritis on renal graft survival

BACKGROUND

Glomerular disease causes graft loss in the intermediate and long term, especially recurrent primary renal disease, negatively impacting graft survival. Thus, it must be considered a differential diagnosis in the evaluation of chronic graft dysfunction.

METHODS

The objectives of our study were to compare the impacts of primary glomerular disease on graft survival and association with interstitial fibrosis/tubular atrophy (IFTA) or transplant glomerulopathy. We examined the influence of the relapse of glomerulonephritis (GN) on renal graft survival in a retrospective study of 1057 patients undergoing renal transplantations between March 1981 and October 2009. Among this group, 128 patients were diagnosed with pretransplant GN by renal biopsy. We examined graft survival on recurrence compared with IFTA and transplant glomerulopathy using Kaplan-Meier analysis.

RESULTS

We analyzed a cohort of 128 patients who were diagnosed with pretransplant GN by renal biopsy, including 28.9% (37) of whom were males. The mean age was 42.04 ± 13.82 years. The most frequent type was immunoglobulin A GN (IgAGN; 31.3%), followed by membranoproliferative GN (MPGN; 28.9%), rapidly progressive GN (RPGN; 16.4%), focal-segmental GN (FSGN; 13.3%), membranous GN (9.4%), and minimal change GN; (0.8%). Among the 16 cases (12.5%) of GN recurrence; MPGN was associated most frequently (n = 10, 28.9%), followed by FSGN (n = 4, 23.5%), RPGN (n = 1, 4.8%), and IgAGN (n = 1, 2.5%). We noted that 11.8% of subjects to be positive for hepatitis C virus; while 3.9% were hepatitis B virus(HBV)-positive. We observed no differences in hepatic serology between patients who experienced recurrence (HBV 6.3% vs hepatitis C virus [HCV] 18.8%) compared with IFTA (HBV 3.1% vs HCV 9.4%). Fifty-one patients (39.8%) were biopsied after transplantation due to impaired renal function: there were recurrences of GN in 12.5% (n = 16), IFTA in 25% (n = 32), and transplant glomerulopathy in 2.3% (n = 3) cases. The average graft survival in our cohort was 8.36 ± 0.59 years. The median patient survival among those who experienced a recurrence was 8.36 ± 1.79 years; 7.19 ± 1.01 years in IFTA patients; and 3.31 ± 0.91 years in patients with transplant glomerulopathy (log-rank P = .06). Upon multivariate analysis, recurrence of GN was not an independent predictor of renal loss.

CONCLUSIONS

MPGN was the type of GN that recurred most frequently followed by FSGN. No differences in graft survival were noted between long-term recurrence of GN and other causes of chronic graft dysfunction. The recurrence of primary disease did not worsen the renal graft prognosis versus other causes of chronic graft dysfunction.

[Characteristics of the pediatric patient before transplantation]

Renal transplantation is the treatment of choice for end-stage renal disease during childhood. In France, access to transplantation is good and even better for children than for adults. Few contraindications, mostly temporary, might delay the transplantation. The different pathologies leading to end-stage renal disease in children require a specific pre-transplantation examination and a careful choice of the type of donor. Prevalence of disease recurrence is greater in children than in adults. It is one of the most frequent post-transplantation complications and contributes to the increase in patient morbidity and graft failure in our pediatrics cohorts. Kidney donations in North America are for the most part live-donation, which is not the case in France. However, thanks to parent's commitment, the ratio of living donor is currently increasing in France.

A case of recurrent focal segmental glomerulosclerosis (FSGS) involving massive proteinuria (>50 g/day) immediately after renal transplantation

A 15-yr-old girl with end-stage kidney disease caused by primary focal segmental glomerulosclerosis (FSGS) underwent a living-related donor kidney transplantation. The allograft functioned well immediately after reperfusion, but massive proteinuria exceeding 50 g/d appeared on day 3. Treatment with rituximab and plasma exchange (PE) successfully decreased the proteinuria to 10 g/d. A biopsy specimen on day 30 showed no segmental glomerulosclerosis but partial interstitial infiltration of inflammatory cells. An increased number of podocytes showed intracytoplasmic vacuolization, and an electron micrograph showed diffuse mild subendothelial edema and foot process effacement. The podocytes were hypertrophied but were not detached from the basement membrane. As the therapies used to reduce the patient's proteinuria were having a limited effect, intravenous steroid pulse therapy followed by low-density lipoprotein apheresis was performed. A biopsy specimen taken on day 120 showed no segmental glomerulosclerosis. Thrombus formation in one glomerulus and packed lymphocytes in the capillary loop of another glomerulus were detected. The patient's clinical course was compatible with FSGS recurrence. Although the early pathological changes were not typical of FSGS, they might be indicative of the primary lesion that subsequently progresses to typical FSGS.

Phenotypic evaluation of B-cell subsets after rituximab for treatment of acute renal allograft rejection in pediatric recipients

BACKGROUND

Recently published pediatric trial of Rituximab for the treatment of CD20+ acute renal allograft rejection (AR) demonstrated transient depletion of circulating/intragraft B cells (Zarkhin et al., Am J Transplant 2008; 8: 2607). In this study, we have evaluated phenotypic definition of circulating B-cell subsets before and after standard of care and B-cell depletional AR therapies.

METHODS

We assessed peripheral B cells by flow cytometry at the time of AR and after AR treatment in 35 pediatric renal transplant recipients: 17 patients with AR who received Rituximab (R-AR; n=11) or steroid pulsing (S-AR; n=6), 18 stable patients with stable graft function with (iSTA; n=10) or without interval infection (hSTA; n=8), and 3 healthy volunteers.

RESULTS

Infections increased memory (P=0.02) and CD19+/CD27⁻/IgD⁻ double negative (DN) B cells (P=0.02) and decreased naive B cells (P=0.01) in iSTA group compared to hSTA patients. Decrease in naive/memory B cells ratio at AR was observed compared with hSTA patients (P=0.01). One year after AR treatment, S-AR patients had persistently lower naive/memory B-cell ratio (P=0.01) and higher DN B cells (P=0.0001) than hSTA patients, whereas after R-AR treatment naive/memory B-cell ratio (P=0.6) and DN B cells (P=0.13) recovered to levels of hSTA patients. R-AR patients with sustained AR resolution (n=8) had trend toward better graft survival (P=0.06) and higher naive B cells (P=0.004) than R-AR relapsers (n=3).

CONCLUSIONS

Increase in circulating memory B cells was seen in pediatric patients at AR. B cells persist as memory after S-AR treatment, whereas Rituximab resulted in repopulation of mostly naive B cells. The heterogeneity in B-cells reconstitution after rejection therapies deserves further investigation as a possible means to follow the clinical and immunologic outcomes of graft rejection.