{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,29]],"date-time":"2026-09-29T06:04:48Z","timestamp":1790661888930,"version":"4.1.0"},"reference-count":46,"publisher":"Wiley","issue":"9","license":[{"start":{"date-parts":[[2026,9,16]],"date-time":"2026-09-16T00:00:00Z","timestamp":1789516800000},"content-version":"vor","delay-in-days":15,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T00:00:00Z","timestamp":1788220800000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Eur J Immunol"],"published-print":{"date-parts":[[2026,9]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>Regulatory B cells (Bregs) are emerging as pivotal modulators of immune balance, yet their dynamics during severe acute respiratory syndrome coronavirus 2 (SARS\u2010CoV\u20102) infection and their response to passive antibody therapy remain largely unexplored. In the immunological sub\u2010study of the randomized, placebo\u2010controlled POLYCOR trial evaluating XAV\u201019, a glyco\u2010humanized polyclonal anti\u2010SARS\u2010CoV\u20102 antibody, we performed longitudinal immune profiling of hospitalized COVID\u201019 patients using spectral flow cytometry, in vitro functional assays, and single\u2010cell RNA sequencing. SARS\u2010CoV\u20102 infection triggered a transient remodeling of the B\u2010cell compartment, with expansion of activated B cells and plasmablasts, contraction of switched memory B cells, and enrichment of B cells expressing regulatory\u2010associated markers, including PD\u2010L1, CD9, granzyme B, and IL\u201010. Transcriptional analyses revealed dynamic reprogramming, characterized by downregulation of adhesion and costimulatory genes (CD27, ITGB7) and emergence of an interferon\u2010driven memory B\u2010cell signature (SOCS1, IFI27). In contrast, XAV\u201019 treatment preserved B\u2010cell homeostasis, showing minimal impact on phenotype, function, and gene expression. Together, these findings uncover a transient regulatory adaptation of B cells during acute COVID\u201019 and demonstrate that XAV\u201019 therapy maintains immune equilibrium, reinforcing its safety and supporting the concept of immunologically neutral passive antibody therapy.<\/jats:p>","DOI":"10.1002\/eji.70284","type":"journal-article","created":{"date-parts":[[2026,9,16]],"date-time":"2026-09-16T07:18:53Z","timestamp":1789543133000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["B\u2010Cell Remodeling and Regulatory Phenotypes During Acute COVID\u201019 Are Unaffected by Polyclonal Anti\u2010SARS\u2010CoV\u20102 Antibody XAV\u201019"],"prefix":"10.1002","volume":"56","author":[{"given":"Nicolas","family":"Degauque","sequence":"first","affiliation":[{"name":"CHU Nantes Nantes Universit\u00e9 INSERM, Center for Research in Transplantation and Translational Immunology UMR 1064 ITUN  Nantes 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