{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"bioRxiv"}],"indexed":{"date-parts":[[2026,10,23]],"date-time":"2026-10-23T21:19:00Z","timestamp":1792790340774,"version":"4.5.0"},"posted":{"date-parts":[[2026,4,23]]},"group-title":"Immunology","reference-count":45,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,4,23]],"date-time":"2026-04-23T00:00:00Z","timestamp":1776902400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"funder":[{"name":"National Institute of Allergy and Infectious Disease","award":["R01AI188364-01"],"award-info":[{"award-number":["R01AI188364-01"]}],"id":[{"id":"https:\/\/ror.org\/043z4tv69","id-type":"ROR","asserted-by":"crossref"}]},{"name":"National Institute of Allergy and Infectious Disease","award":["R21AI178426-02"],"award-info":[{"award-number":["R21AI178426-02"]}],"id":[{"id":"https:\/\/ror.org\/043z4tv69","id-type":"ROR","asserted-by":"crossref"}]},{"name":"National Science Foundation Graduate Research Fellowship","award":["DGE-2140004"],"award-info":[{"award-number":["DGE-2140004"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,10,9]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                <jats:p>\n                  Regulatory T cells (Tregs) prevent autoimmunity through suppressive functions largely programmed by the transcription factor FOXP3. Humans express two major alternatively spliced isoforms of FOXP3: a full-length version containing all coding exons (FOXP3-FL) and a version lacking Exon 2 (FOXP3-\u0394E2). Sole FOXP3-\u0394E2 expression causes lethal IPEX syndrome, indicating that FOXP3 Exon 2 is essential for full Treg function. Here, we used Foxp3-\u0394E2 mice to determine how Foxp3 Exon 2 impacts the functional differentiation of Tregs at homeostasis and during inflammation. Analysis of central and effector Foxp3-\u0394E2 Treg populations revealed dysfunctional effector Treg programming, including reduced expression of IL-2 receptor subunits, CTLA-4, and tissue-homing chemokine receptors. During influenza infection, reduced IL-2 regulation by Foxp3-\u0394E2 Tregs and decreased Foxp3-\u0394E2 Treg localization to the T cell zone during priming contributed to enhanced acute and memory CD8\n                  <jats:sup>+<\/jats:sup>\n                  T cell responses. Thus, dysfunctional effector Treg programming by the Foxp3-\u0394E2 isoform impairs suppressive function, resulting in failure to restrain CD8\n                  <jats:sup>+<\/jats:sup>\n                  T cells and aberrant immune responses.\n                <\/jats:p>\n                <jats:sec>\n                  <jats:title>One Sentence Summary<\/jats:title>\n                  <jats:p>\n                    Foxp3-\u0394E2 expressing regulatory T cells have dysfunctional effector programming which impairs their IL-2 regulation function and co-localization with conventional T cells during priming, thereby enhancing CD8\n                    <jats:sup>+<\/jats:sup>\n                    T cell responses.\n                  <\/jats:p>\n                <\/jats:sec>\n                <jats:sec>\n                  <jats:title>Graphical abstract<\/jats:title>\n                  <jats:fig id=\"ufig1\" position=\"float\" orientation=\"portrait\" fig-type=\"figure\">\n                    <jats:graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"719728v2_ufig1\" position=\"float\" orientation=\"portrait\"\/>\n                  <\/jats:fig>\n                  <jats:p>\n                    Dysfunctional Foxp3-\u0394E2 effector Treg programming includes reduced IL-2R\u03b1 and CXCR3 expression and increased CCR7 expression, driving reduced Foxp3-\u0394E2 Treg IL-2 sink activity and localization to the T cell zone of the lymph node during influenza viral infection. Together, these defective mechanisms of suppression by Foxp3-\u0394E2 Tregs promote CD8\n                    <jats:sup>+<\/jats:sup>\n                    T cell responses during acute infection and memory formation in Foxp3-\u0394E2 mice.\n                  <\/jats:p>\n                <\/jats:sec>","DOI":"10.64898\/2026.04.20.719728","type":"posted-content","created":{"date-parts":[[2026,4,23]],"date-time":"2026-04-23T17:25:18Z","timestamp":1776965118000},"source":"Crossref","is-referenced-by-count":0,"title":["Dysfunctional effector programming in Foxp3-\u0394E2 Tregs promotes enhanced CD8\n                  <sup>+<\/sup>\n                  T cell responses"],"prefix":"10.64898","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9257-951X","authenticated-orcid":false,"given":"Kristin N.","family":"Weinstein","sequence":"first","affiliation":[{"name":"Center for Fundamental Immunology, Benaroya Research Institute; Seattle, USA"},{"name":"Department of Immunology, University of Washington; Seattle, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zoe H.","family":"Bishop","sequence":"additional","affiliation":[{"name":"Center for Fundamental Immunology, Benaroya Research Institute; Seattle, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Elya A.","family":"Shamskhou","sequence":"additional","affiliation":[{"name":"Department of Immunology, University of Washington; Seattle, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Finnegan N.","family":"Barry","sequence":"additional","affiliation":[{"name":"Center for Fundamental Immunology, Benaroya Research Institute; Seattle, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gabriela","family":"Verdezoto","sequence":"additional","affiliation":[{"name":"Department of Immunology, University of Washington; Seattle, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marissa","family":"de Leon","sequence":"additional","affiliation":[{"name":"Center for Fundamental Immunology, Benaroya Research Institute; Seattle, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Joseph R.","family":"Albe","sequence":"additional","affiliation":[{"name":"Center for Fundamental Immunology, Benaroya Research Institute; Seattle, USA"},{"name":"Department of Immunology, University of Washington; Seattle, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Andrew","family":"Koval","sequence":"additional","affiliation":[{"name":"Center for Systems Immunology, Benaroya Research Institute; Seattle, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Baohua","family":"Zhou","sequence":"additional","affiliation":[{"name":"School of Medicine, Indiana University, Indianapolis, IN, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Phillip P.","family":"Domeier","sequence":"additional","affiliation":[{"name":"Center for Fundamental Immunology, Benaroya Research Institute; Seattle, USA"},{"name":"Department of Microbiology and Immunology, The University of British Columbia; Vancouver, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Michael Y.","family":"Gerner","sequence":"additional","affiliation":[{"name":"Department of Immunology, University of Washington; Seattle, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9652-7178","authenticated-orcid":false,"given":"Daniel J.","family":"Campbell","sequence":"additional","affiliation":[{"name":"Center for Fundamental Immunology, Benaroya Research Institute; Seattle, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Steven F.","family":"Ziegler","sequence":"additional","affiliation":[{"name":"Center for Fundamental Immunology, Benaroya Research Institute; Seattle, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"54368","reference":[{"key":"2026101308050520000_2026.04.20.719728v2.1","doi-asserted-by":"publisher","DOI":"10.1016\/S0092-8674(00)80856-9"},{"key":"2026101308050520000_2026.04.20.719728v2.2","doi-asserted-by":"publisher","DOI":"10.4049\/jimmunol.168.12.5979"},{"key":"2026101308050520000_2026.04.20.719728v2.3","doi-asserted-by":"crossref","unstructured":"K. Wing et al., CTLA-4 Control over Foxp3+ Regulatory T Cell Function. Science 322, (2008-10-10).","DOI":"10.1126\/science.1160062"},{"key":"2026101308050520000_2026.04.20.719728v2.4","doi-asserted-by":"crossref","unstructured":"The inhibitory cytokine IL-35 contributes to regulatory T-cell function - PubMed. Nature 450, (11\/22\/2007).","DOI":"10.1038\/nature06306"},{"key":"2026101308050520000_2026.04.20.719728v2.5","doi-asserted-by":"crossref","unstructured":"L. W. Collison , M. R. Pillai , V. Chaturvedi , D. A. A. Vignali , Regulatory T Cell Suppression Is Potentiated by Target T Cells in a Cell Contact, IL-35- and IL-10-Dependent Manner. 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