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
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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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author 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
author_facet 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
author_sort Konstantinos Mengrelis
collection DOAJ
description 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.
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spelling doaj-art-45669ae98b4f43d9b9dffb9bdc79578a2025-08-20T02:45:34ZengMDPI AGCells2073-44092025-07-011414108610.3390/cells14141086IL-2 Complex Therapy Mitigates Humoral Rejection of Fully Mismatched Skin Allografts by Inhibiting IgG Alloantibody FormationKonstantinos Mengrelis0Mario Wiletel1Romy Steiner2Anna M. Weijler3Laurenz Wolner4Valentina Stolz5Milos Nikolic6Daniel Simon7Florian Frommlet8Jonathan Sprent9Hannes Stockinger10Nina Pilat11Department of Cardiac and Thoracic Aortic Surgery, Medical University of Vienna, 1090 Vienna, AustriaDepartment of General Surgery, Division of Transplantation, Medical University of Vienna, 1090 Vienna, AustriaDepartment of Cardiac and Thoracic Aortic Surgery, Medical University of Vienna, 1090 Vienna, AustriaDepartment of General Surgery, Division of Transplantation, Medical University of Vienna, 1090 Vienna, AustriaCenter for Biomedical Research and Translational Surgery, Medical University of Vienna, 1090 Vienna, AustriaDivision of Immunobiology, Institute of Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, AustriaDepartment of General Surgery, Division of Transplantation, Medical University of Vienna, 1090 Vienna, AustriaDepartment of General Surgery, Division of Transplantation, Medical University of Vienna, 1090 Vienna, AustriaCenter for Medical Statistics, Informatics and Intelligent Systems, Section for Medical Statistics, Medical University of Vienna, 1090 Vienna, AustriaGarvan Institute of Medical Research, Immunology Division, Sydney, NSW 2010, AustraliaCenter for Pathophysiology, Infectiology and Immunology, Institute for Hygiene and Applied Immunology, Medical University of Vienna, Vienna 1090, AustriaDepartment of Cardiac and Thoracic Aortic Surgery, Medical University of Vienna, 1090 Vienna, AustriaAntibody-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.https://www.mdpi.com/2073-4409/14/14/1086transplantationregulatory T cellsgerminal centerdonor-specific antibodieshumoral tolerance
spellingShingle 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
IL-2 Complex Therapy Mitigates Humoral Rejection of Fully Mismatched Skin Allografts by Inhibiting IgG Alloantibody Formation
Cells
transplantation
regulatory T cells
germinal center
donor-specific antibodies
humoral tolerance
title IL-2 Complex Therapy Mitigates Humoral Rejection of Fully Mismatched Skin Allografts by Inhibiting IgG Alloantibody Formation
title_full IL-2 Complex Therapy Mitigates Humoral Rejection of Fully Mismatched Skin Allografts by Inhibiting IgG Alloantibody Formation
title_fullStr IL-2 Complex Therapy Mitigates Humoral Rejection of Fully Mismatched Skin Allografts by Inhibiting IgG Alloantibody Formation
title_full_unstemmed IL-2 Complex Therapy Mitigates Humoral Rejection of Fully Mismatched Skin Allografts by Inhibiting IgG Alloantibody Formation
title_short IL-2 Complex Therapy Mitigates Humoral Rejection of Fully Mismatched Skin Allografts by Inhibiting IgG Alloantibody Formation
title_sort il 2 complex therapy mitigates humoral rejection of fully mismatched skin allografts by inhibiting igg alloantibody formation
topic transplantation
regulatory T cells
germinal center
donor-specific antibodies
humoral tolerance
url https://www.mdpi.com/2073-4409/14/14/1086
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