Department of Surgery, Division of Transplantation, University of Wisconsin–Madison, Madison, WI, USA; Corresponding author
Yusuke Tomita
Department of Surgery, Division of Transplantation, University of Wisconsin–Madison, Madison, WI, USA
Ewa Jankowska-Gan
Department of Surgery, Division of Transplantation, University of Wisconsin–Madison, Madison, WI, USA
Diego A. Lema
Department of Surgery, Division of Transplantation, University of Wisconsin–Madison, Madison, WI, USA
Matt P. Arvedson
Department of Surgery, Division of Transplantation, University of Wisconsin–Madison, Madison, WI, USA
Ashita Nair
Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin–Madison, Madison, WI, USA
William Bracamonte-Baran
Department of Surgery, Division of Transplantation, University of Wisconsin–Madison, Madison, WI, USA
Ying Zhou
Department of Surgery, Division of Transplantation, University of Wisconsin–Madison, Madison, WI, USA
Kristy K. Meyer
Department of Pathology and Laboratory Medicine, School of Medicine and Public Health, University of Wisconsin–Madison, Madison, WI, USA; Pathology and Laboratory Services, William S. Middleton Memorial Veterans Hospital, Madison, WI, USA
Weixiong Zhong
Department of Pathology and Laboratory Medicine, School of Medicine and Public Health, University of Wisconsin–Madison, Madison, WI, USA; Pathology and Laboratory Services, William S. Middleton Memorial Veterans Hospital, Madison, WI, USA
Deepali V. Sawant
Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
Andrea L. Szymczak-Workman
Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
Qianxia Zhang
Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
Creg J. Workman
Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
Seungpyo Hong
Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin–Madison, Madison, WI, USA; Yonsei Frontier Lab and Department of Pharmacy, Yonsei University, Seoul, Korea
Dario A.A. Vignali
Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Tumor Microenvironment Center, UPMC Hillman Cancer Center, Pittsburgh, PA, USA
William J. Burlingham
Department of Surgery, Division of Transplantation, University of Wisconsin–Madison, Madison, WI, USA
Summary: Interleukin-35 (IL-35) is an immunosuppressive cytokine composed of Epstein-Barr-virus-induced protein 3 (Ebi3) and IL-12α chain (p35) subunits, yet the forms that IL-35 assume and its role in peripheral tolerance remain elusive. We induce CBA-specific, IL-35-producing T regulatory (Treg) cells in TregEbi3WT C57BL/6 reporter mice and identify IL-35 producers by expression of Ebi3TdTom gene reporter plus Ebi3 and p35 proteins. Curiously, both subunits of IL-35 are displayed on the surface of tolerogen-specific Foxp3+ and Foxp3neg (iTr35) T cells. Furthermore, IL-35 producers, although rare, secrete Ebi3 and p35 on extracellular vesicles (EVs) targeting a 25- to 100-fold higher number of T and B lymphocytes, causing them to acquire surface IL-35. This surface IL-35 is absent when EV production is inhibited or if Ebi3 is genetically deleted in Treg cells. The unique ability of EVs to coat bystander lymphocytes with IL-35, promoting exhaustion in, and secondary suppression by, non-Treg cells identifies a novel mechanism of infectious tolerance. : Sullivan et al. show that while many factors and cytokines contribute to primary immunosuppression, EV-associated IL-35 uniquely promotes “infectious” tolerance not only by inducing IL-35 production in non-Treg cells but also by causing an immunosuppressive phenotype in EV-acquiring T and B cells, leading to secondary suppression of immune responses. Keywords: IL-35, extracellular vesicles, cytokines, tolerance, Treg, tetraspanin, Ebi3, p35, CD81
