B10 cells: Development, phenotype, and function in cancer

B10 cells, a specialized subset of regulatory B cells, have been identified in both mice and humans. These cells are characterized by their regulatory impact on immune dynamics, principally through their secretion of interleukin-10 (IL-10), a cytokine known for its anti-inflammatory properties. The pivotal role of immune mediators such as B10 cells is to maintain a delicate equilibrium between antitumor immunity and tumor-promoting responses. Emerging studies have cast B10 cells as key suppressors in the antitumor immune arsenal. They operate in synergy with a spectrum of immune cells within the innate and adaptive spectrums, contributing to a milieu that favors tumor progression and metastatic spread. In this comprehensive review, we will discuss the ontogeny, phenotype and effector functions of B10 cells in murine systems. We will also review the role of B10 cells in oncological models in animal studies and extend these findings to the human clinical context, elucidating their role in facilitating tumor immune evasion. A thorough understanding of these processes is imperative for the strategic targeting and attenuation of B10 cell activity, which is anticipated to be a cornerstone in the advancement of effective cancer immunotherapy strategies.