Human Secretory IgM Emerges from Plasma Cells Clonally Related to Gut Memory B Cells and Targets Highly Diverse Commensals

• DOI: 10.1016/j.immuni.2017.06.013
• Publication Date: 2017-07-11T14:34:42Z
• Authors: Giuliana Magri; Laura Comerma; Marc Pybus; Jordi Sintes; David Lligé; Daniel Segura-Garzón; Sabrina Bascones; Ada Yeste; Emilie K. Grasset; Cindy Gutzeit; Mathieu Uzzan; Meera Ramanujam; Menno C. van Zelm; Raquel Albero-Gon...; Ivonne Vazquez; Mar Iglesias; Sergi Serrano; Lucía Márquez; Elena Mercade; Saurabh Mehandru; Andrea Cerutti
• Keywords: Commensalism; Immunoglobulin A; Memory B cell; Immunoglobulin M

Secretory 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 B disseminated throughout the intestine but rare systemic lymphoid organs. In addition sharing gut-specific gene signature with IgA+ cells, some clonotypes switched IgA response T cell-independent or cell-dependent signals. These signals induced IgM which, together from affiliated PCs, recognized mucus-embedded commensals. Bacteria by human dually coated SIgA showed increased richness diversity compared IgA-only-coated uncoated bacteria. Thus, may emerge pre-existing rather newly activated naive could help anchor highly diverse commensal communities mucus.