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Figure 1. The influence of EVs on B cell development and activation. EVs (shown as small vesicles colored according to the donor cell) secreted by developing B cells can affect B cell homeostasis by transferring pro-apoptotic receptors to recipient B cells and can limit class-switching. In addition, EVs secreted by MSCs can limit B cell survival by downregulating PI3K signaling in bone marrow-derived or circulating B cells. EVs secreted by B cells can affect T cell activation directly via MHC-mediated presentation of peptide to T cells or via decorating FDC. Moreover, EVs released by Mast cells can promote antibody class-switching to IgE while T cell-derived EVs can upregulate PI3K pathway activation to increase secretion of IgG. EVs secreted by antibody-producing cells, such as plasma cells shown here, can neutralize Ag in circulation. Activation is indicated by arrowheads, and inhibition is indicated by perpendicular lines. Dashed lines indicate EV release from donor cells. Created in BioRender. Christian, S. (2025) https://BioRender.com/3607mjk. EVs: Extracellular vesicles; MSCs: mesenchymal stromal cells; PI3K: phosphoinositide 3-kinase; Akt: protein kinase B; MHC: major histocompatibility complex; FDC: follicular dendritic cell; Ag: antigen; BCR: B cell receptor; pro-BCR: pro-B cell receptor; GC B cell: germinal center B cell; PTEN: phosphatase and tensin homolog; Bim: Bcl-2-like protein 11.