Tumor-infiltrating B cells participate in shaping the immunosuppressive microenvironment in solid tumors.

Tumor-infiltrating B cells (TIBs) exhibit dual roles in the tumor microenvironment (TME) of solid tumors. While they can enhance anti-tumor immunity through antibody production and immune activation, certain subsets-such as regulatory B cells (Bregs) and immunosuppressive plasma cells-contribute to immune evasion by secreting inhibitory factors. In this review, we analyze TIB heterogeneity, with a particular focus on their differentiation pathways, including the distinct roles of germinal center (GC) and extrafollicular (EF) responses in immune regulation. We further summarize the diverse functions of TIBs in tumor immunity, exploring their metabolic adaptations and defects in antibody maturation. A deeper understanding of TIB biology and their underlying mechanisms may pave the way for more precise and effective immunotherapeutic strategies against cancer.