Kidney Week

Abstract: TH-PO0426

Post-Rituximab Relapse Is Associated with Antinephrin Memory B Cells in Pediatric Patients with Idiopathic Nephrotic Syndrome

Session Information

• Glomerular Diseases: Autoimmune Diseases
  October 22, 2026 | Location: Exhibit Hall A, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Glomerular Diseases

• 1401 Glomerular Diseases: Mechanisms, including Podocyte Biology

Authors

• Colucci, Manuela, Ospedale Pediatrico Bambino Gesu IRCCS, Rome, Lazio, Italy

Manuela Colucci, PhD

• Riganati, Martina, Ospedale Pediatrico Bambino Gesu IRCCS, Rome, Lazio, Italy

Martina Riganati

• Zotta, Federica, Ospedale Pediatrico Bambino Gesu IRCCS, Rome, Lazio, Italy

Federica Zotta

• Gargiulo, Antonio, Ospedale Pediatrico Bambino Gesu IRCCS, Rome, Lazio, Italy

Antonio Gargiulo, MD

• Angeletti, Andrea, Istituto Giannina Gaslini, Genoa, Liguria, Italy

Andrea Angeletti, MD, PhD

• Caridi, Gianluca, Istituto Giannina Gaslini, Genoa, Liguria, Italy

Gianluca Caridi, MBBS, MBChB

• Kajana, Xhuliana, Istituto Giannina Gaslini, Genoa, Liguria, Italy

Xhuliana Kajana, MS, MSc

• Emma, Francesco, Ospedale Pediatrico Bambino Gesu IRCCS, Rome, Lazio, Italy

Francesco Emma, MD

• Vivarelli, Marina, Ospedale Pediatrico Bambino Gesu IRCCS, Rome, Lazio, Italy

Marina Vivarelli, MD

Background

The efficacy of B-cell-depleting agents such as rituximab (RTX) and the identification of anti-nephrin autoantibodies support a key role of B cells in the pathogenesis of idiopathic nephrotic syndrome (INS). Memory B cells have been also implicated, serving as predictors of recurrence. However, the duration of drug-free remission after RTX treatment varies widely, and current anti-nephrin autoantibody detection methods are technically complex.

Methods

This study investigated whether the presence of anti-nephrin-specific memory B cells is associated with post-RTX relapse in pediatric INS. We included 13 children treated with RTX, classified as relapsing (n=9) or non-relapsing (n=4) during a 24-month follow-up. Controls with non–immune-mediated renal diseases (n=10) were also enrolled. Total and anti-nephrin-specific IgG-producing memory B cells were quantified using a novel Fluorospot assay developed in our laboratory at baseline and at last follow-up (defined as 24 months for non-relapsers and at relapse/repeated RTX infusion for relapsers).

Results

Median total IgG-producing memory B-cell counts were significantly reduced in INS patients prior to RTX treatment compared to controls, likely due to immunosuppressive drugs administered at baseline. In contrast, anti-nephrin IgG-producing memory B-cell levels were significantly higher in INS patients than in controls. In the relapsing group, recurrence occurred after a mean of 15.8 ± 8.0 months. Median total IgG-producing memory B-cell counts were comparable between relapsing and non-relapsing patients at baseline (p=0.6) and at last follow-up (p=0.2). However, anti-nephrin IgG-producing memory B-cell levels, initially similar in both groups (p=0.74), significantly increased at last follow-up in relapsers (p=0.03) but were completely absent in all non-relapsing patients (p=0.01 vs. relapsers).
These findings suggest that RTX effectively and durably depletes anti-nephrin-specific memory B cells in patients who achieve sustained remission, whereas these cells persist or re-emerge in those who relapse.

Conclusion

The novel Fluorospot assay developed in our laboratory enables efficient enumeration of anti-nephrin memory B cells, which may help identify pediatric INS patients at risk of relapse following RTX treatment. Further studies are needed to assess its predictive value in identifying relapse risk before clinical recurrence.