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  1. Article ; Online: B cells in the balance: Offsetting self-reactivity avoidance with protection against foreign.

    Young, Clara / Lau, Angelica W Y / Burnett, Deborah L

    Frontiers in immunology

    2022  Volume 13, Page(s) 951385

    Abstract: Antibodies are theoretically limitless in their diversity and specificity to foreign antigens; however they are constrained by the need to avoid binding to self. Germinal centers (GC) allow diversification and maturation of the antibody response towards ... ...

    Abstract Antibodies are theoretically limitless in their diversity and specificity to foreign antigens; however they are constrained by the need to avoid binding to self. Germinal centers (GC) allow diversification and maturation of the antibody response towards the foreign antigen. While self-tolerance mechanisms controlling self-reactivity during B cell maturation are well recognized, the mechanisms by which GCs balance self-tolerance and foreign binding especially in the face of cross-reactivity between self and foreign, remain much less well defined. In this review we explore the extent to which GC self-tolerance restricts affinity maturation. We present studies suggesting that the outcome is situationally dependent, affected by affinity and avidity to self-antigen, and the extent to which self-binding and foreign-binding are interdependent. While auto-reactive GC B cells can mutate away from self while maturing towards the foreign antigen, if no mutational trajectories allow for self-reactive redemption, self-tolerance prevails and GC responses to the foreign pathogen are restricted, except when self-tolerance checkpoints are relaxed. Finally, we consider whether polyreactivity is subject to the same level of restriction in GC responses, especially if polyreactivity is linked to an increase in foreign protection, as occurs in certain broadly neutralizing antibodies. Overall, the outcomes for GC B cells that bind self-antigen can range from redemption, transient relaxation in self-tolerance or restriction of the antibody response to the foreign pathogen.
    MeSH term(s) Autoantigens ; B-Lymphocytes ; Germinal Center ; Immune Tolerance ; Self Tolerance
    Chemical Substances Autoantigens
    Language English
    Publishing date 2022-07-25
    Publishing country Switzerland
    Document type Journal Article ; Review ; Research Support, Non-U.S. Gov't
    ZDB-ID 2606827-8
    ISSN 1664-3224 ; 1664-3224
    ISSN (online) 1664-3224
    ISSN 1664-3224
    DOI 10.3389/fimmu.2022.951385
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: BAFFR controls early memory B cell responses but is dispensable for germinal center function.

    Lau, Angelica W Y / Turner, Vivian M / Bourne, Katherine / Hermes, Jana R / Chan, Tyani D / Brink, Robert

    The Journal of experimental medicine

    2020  Volume 218, Issue 2

    Abstract: The TNF superfamily ligand BAFF maintains the survival of naive B cells by signaling through its surface receptor, BAFFR. Activated B cells maintain expression of BAFFR after they differentiate into germinal center (GC) or memory B cells (MBCs). However, ...

    Abstract The TNF superfamily ligand BAFF maintains the survival of naive B cells by signaling through its surface receptor, BAFFR. Activated B cells maintain expression of BAFFR after they differentiate into germinal center (GC) or memory B cells (MBCs). However, the functions of BAFFR in these antigen-experienced B cell populations remain unclear. Here, we show that B cell-intrinsic BAFFR does not play a significant role in the survival or function of GC B cells or in the generation of the somatically mutated MBCs derived from them. Instead, BAFF/BAFFR signaling was required to generate the unmutated, GC-independent MBCs that differentiate directly from activated B cell blasts early in the response. Furthermore, amplification of BAFFR signaling in responding B cells did not affect GCs or the generation of GC-derived MBCs but greatly expanded the GC-independent MBC response. Although BAFF/BAFFR signaling specifically controlled the formation of the GC-independent MBC response, both types of MBCs required input from this pathway for optimal long-term survival.
    MeSH term(s) Animals ; B-Cell Activating Factor/immunology ; B-Cell Activating Factor/metabolism ; B-Cell Activation Factor Receptor/immunology ; B-Cell Activation Factor Receptor/metabolism ; B-Lymphocytes/immunology ; B-Lymphocytes/metabolism ; Germinal Center/immunology ; Germinal Center/metabolism ; Immunologic Memory/immunology ; Mice ; Mice, Inbred C57BL ; Signal Transduction/physiology
    Chemical Substances B-Cell Activating Factor ; B-Cell Activation Factor Receptor ; Tnfrsf13c protein, mouse
    Language English
    Publishing date 2020-11-23
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 218343-2
    ISSN 1540-9538 ; 0022-1007
    ISSN (online) 1540-9538
    ISSN 0022-1007
    DOI 10.1084/jem.20191167
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Positive selection of IgG

    Sundling, Christopher / Lau, Angelica W Y / Bourne, Katherine / Young, Clara / Laurianto, Candy / Hermes, Jana R / Menzies, Rosemary J / Butt, Danyal / Kräutler, Nike J / Zahra, David / Suan, Dan / Brink, Robert

    Immunity

    2021  Volume 54, Issue 5, Page(s) 988–1001.e5

    Abstract: Positive selection of high-affinity B cells within germinal centers (GCs) drives affinity maturation of antibody responses. Here, we examined the mechanism underlying the parallel transition from immunoglobulin M (IgM) to IgG. Early GCs contained mostly ... ...

    Abstract Positive selection of high-affinity B cells within germinal centers (GCs) drives affinity maturation of antibody responses. Here, we examined the mechanism underlying the parallel transition from immunoglobulin M (IgM) to IgG. Early GCs contained mostly unswitched IgM
    MeSH term(s) Animals ; Antibody Formation/immunology ; Antigens/immunology ; B-Lymphocytes/immunology ; Female ; Germinal Center/immunology ; Immunoglobulin Class Switching/immunology ; Immunoglobulin G/immunology ; Immunoglobulin M/immunology ; Immunoglobulin Variable Region/immunology ; Male ; Mice ; Mice, Inbred C57BL ; Mice, Transgenic ; Sheep/immunology ; Somatic Hypermutation, Immunoglobulin/immunology
    Chemical Substances Antigens ; Immunoglobulin G ; Immunoglobulin M ; Immunoglobulin Variable Region
    Language English
    Publishing date 2021-04-14
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1217235-2
    ISSN 1097-4180 ; 1074-7613
    ISSN (online) 1097-4180
    ISSN 1074-7613
    DOI 10.1016/j.immuni.2021.03.013
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Apoptotic cell fragments locally activate tingible body macrophages in the germinal center.

    Grootveld, Abigail K / Kyaw, Wunna / Panova, Veera / Lau, Angelica W Y / Ashwin, Emily / Seuzaret, Guillaume / Dhenni, Rama / Bhattacharyya, Nayan Deger / Khoo, Weng Hua / Biro, Maté / Mitra, Tanmay / Meyer-Hermann, Michael / Bertolino, Patrick / Tanaka, Masato / Hume, David A / Croucher, Peter I / Brink, Robert / Nguyen, Akira / Bannard, Oliver /
    Phan, Tri Giang

    Cell

    2023  Volume 186, Issue 6, Page(s) 1144–1161.e18

    Abstract: Germinal centers (GCs) that form within lymphoid follicles during antibody responses are sites of massive cell death. Tingible body macrophages (TBMs) are tasked with apoptotic cell clearance to prevent secondary necrosis and autoimmune activation by ... ...

    Abstract Germinal centers (GCs) that form within lymphoid follicles during antibody responses are sites of massive cell death. Tingible body macrophages (TBMs) are tasked with apoptotic cell clearance to prevent secondary necrosis and autoimmune activation by intracellular self antigens. We show by multiple redundant and complementary methods that TBMs derive from a lymph node-resident, CD169-lineage, CSF1R-blockade-resistant precursor that is prepositioned in the follicle. Non-migratory TBMs use cytoplasmic processes to chase and capture migrating dead cell fragments using a "lazy" search strategy. Follicular macrophages activated by the presence of nearby apoptotic cells can mature into TBMs in the absence of GCs. Single-cell transcriptomics identified a TBM cell cluster in immunized lymph nodes which upregulated genes involved in apoptotic cell clearance. Thus, apoptotic B cells in early GCs trigger activation and maturation of follicular macrophages into classical TBMs to clear apoptotic debris and prevent antibody-mediated autoimmune diseases.
    MeSH term(s) Apoptosis ; B-Lymphocytes ; Germinal Center ; Lymph Nodes/cytology ; Macrophages/cytology ; Macrophages/metabolism
    Language English
    Publishing date 2023-03-02
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 187009-9
    ISSN 1097-4172 ; 0092-8674
    ISSN (online) 1097-4172
    ISSN 0092-8674
    DOI 10.1016/j.cell.2023.02.004
    Database MEDical Literature Analysis and Retrieval System OnLINE

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