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. 2021 Jun 7;9:678127. doi: 10.3389/fcell.2021.678127

FIGURE 3.

FIGURE 3

Dual role of tumor-infiltrating B cells. (A) B cells scatteredly distributed throughout the tumor bulk may acquire immunosuppressive phenotypes in response to stimulation with TGF-β secreted by fibroblasts, Tregs or M2 macrophages. They can release IL-10, IL-35, and TGF-β that support Treg expansion and Th2/M2 polarization, while suppressing effector T cell activity, which is potentialized by B cell PD-L1 expression. VEGF-producing B cells may also promote tumor progression through neoangiogenesis.(B) Tumor-infiltrating B cells organized in well-structured TLSs coordinate anti-tumor immune responses through multiple mechanisms. They can present tumor-derived antigens to T cells and secrete cytokines such as IFN-γ and IL-12 that support Th1/M1 polarization and CD8+ T cell cytotoxicity. Tumor-specific antibodies secreted by plasma cells can trigger the complement cascade, mediate phagocytosis of tumor cells, and antibody-dependent cell cytotoxicity by NK cells. Activated B cells may also directly kill tumor cells by secreting TRAIL and granzyme B.