IL-2 Complex Therapy Mitigates Humoral Rejection of Fully Mismatched Skin Allografts by Inhibiting IgG Alloantibody Formation

Antibody-mediated rejection (ABMR) caused by donor-specific Abs (DSAs) is still the leading cause of late graft loss following clinical organ transplantation, and effective strategies to combat ABMR are still elusive. We previously showed that rIL-2 complexed with anti-IL-2 mAb clone JES6-1A12 (IL-2...

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Main Authors: Konstantinos Mengrelis, Mario Wiletel, Romy Steiner, Anna M. Weijler, Laurenz Wolner, Valentina Stolz, Milos Nikolic, Daniel Simon, Florian Frommlet, Jonathan Sprent, Hannes Stockinger, Nina Pilat
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Cells
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Online Access:https://www.mdpi.com/2073-4409/14/14/1086
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Summary:Antibody-mediated rejection (ABMR) caused by donor-specific Abs (DSAs) is still the leading cause of late graft loss following clinical organ transplantation, and effective strategies to combat ABMR are still elusive. We previously showed that rIL-2 complexed with anti-IL-2 mAb clone JES6-1A12 (IL-2 cplx) leads to the selective expansion of regulatory T cells (Tregs) and the prolonged survival of MHC-mismatched skin allografts. Although the grafts were eventually rejected, mice failed to develop DSAs. Here, we investigated the impact of IL-2 cplx on the humoral response and germinal center (GC) reaction during allograft rejection. IL-2 cplx treatment prevents Bcl-6 upregulation, leading to suppressed development of GC T and B cells. The IL-2 cplx-induced impairment of GC development limits IgG allo-Ab production but allows for IgM synthesis. By employing a hapten–carrier system to investigate affinity maturation, we found that IL-2 cplx induces a distinct shift in specific Ab production favoring low-affinity IgM while simultaneously decreasing IgG responses. These findings illuminate the potential of IL-2 cplx therapy for inducing humoral tolerance, potentially paving the way for refining strategies aimed at preventing and treating ABMR.
ISSN:2073-4409