Magri, Giuliana, 1978-Pybus Oliveras, Marc, 1985-Sintes, JordiLligé, DavidSegura-Garzón, DanielBascones Gleave, Sabrina, 1985-Yeste, AdaGrasset, Emilie K.Gutzeit, CindyUzzan, MathieuRamanujam, Meeravan Zelm, Menno C.Albero-González, RaquelVazquez de las Heras, IvonneIglesias, MarSerrano Figueras, SergiMárquez, LucíaMercade, ElenaMehandru, SaurabhCerutti, Andrea, 1965-2018-06-052018-06-052017Magri G, Comerma L, Pybus M, Sintes J, Lligé D, Segura-Garzón D. et al. Human Secretory IgM Emerges from Plasma Cells Clonally Related to Gut Memory B Cells and Targets Highly Diverse Commensals. Immunity. 2017 Jul 18;47(1):118-134.e8. DOI: 10.1016/j.immuni.2017.06.0131074-7613http://hdl.handle.net/10230/34830Secretory immunoglobulin A (SIgA) enhances host-microbiota symbiosis, whereas SIgM remains poorly understood. We found that gut IgM+ plasma cells (PCs) were more abundant in humans than mice and clonally related to a large repertoire of memory IgM+ B cells disseminated throughout the intestine but rare in systemic lymphoid organs. In addition to sharing a gut-specific gene signature with memory IgA+ B cells, memory IgM+ B cells were related to some IgA+ clonotypes and switched to IgA in response to T cell-independent or T cell-dependent signals. These signals induced abundant IgM which, together with SIgM from clonally affiliated PCs, recognized mucus-embedded commensals. Bacteria recognized by human SIgM were dually coated by SIgA and showed increased richness and diversity compared to IgA-only-coated or uncoated bacteria. Thus, SIgM may emerge from pre-existing memory rather than newly activated naive IgM+ B cells and could help SIgA to anchor highly diverse commensal communities to mucus.application/pdfeng© 2017 The Authors. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).Tracte gastrointestinalIntestins--Microbiologiainfo:eu-repo/semantics/articlehttp://dx.doi.org/10.1016/j.immuni.2017.06.013IgAIgMGutHumanMemory B cellsMicrobiotaMucosaPlasma cellsRepertoireinfo:eu-repo/semantics/openAccess