Figure 1. Impact of B cells on carcinogenesis and tumor progression. B cells release cytokines, such as lymphotoxins, that mediate the androgen-independent activation of signal transducer and activator of transcription 3 (STAT3) and inhibitor of κB kinase α (IKKα), thus favoring tumor progression.²⁹ Other cytokines such as tumor necrosis factor α (TNFα) stimulate the development of regulatory B cells (Bregs).²⁶ While plasma cells are required for antibody-dependent cell cytotoxicity (ADCC), as they are the actual producer of tumor-specific antibodies,²⁵ the resulting immune complexes may contribute to the establishment of a tumorigenic environment by stimulating Fcγ receptors (FcγRs).²⁷ Furthermore, Bregs can promote oncogenesis by secreting interleukin-10 (IL-10) and transforming growth factor β (TGFβ), hence suppressing CD8⁺ T-cell cytotoxicity and converting/recruiting CD4⁺CD25⁺FOXP3⁺ regulatory T cells (Tregs).^24,78 Such B cell activities normally shift the balance of tumor-specific immune response toward immunosuppression, hence sustaining tumor progression. APBC: antigen-presenting B cell.