Expansion of B10 cells in vitro: Pathways, techniques and applications in transplantation (Review)

Cellular immunotherapy represents a pivotal treatment modality in clinical practice. Regulatory B cells (Bregs), a key subset of B lymphocytes, hold promise in the management of autoimmune diseases, cancer and transplantation immunity. The expansion of Bregs for cell therapy is a promising strategy to alleviate inflammation and promote immune tolerance. Achieving immune tolerance relies on balance between regulatory and effector cells. One primary objective of cellular therapy is to shift this balance towards Bregs, fostering a more tolerant immune microenvironment. The adoptive transfer of Bregs not only increases their quantity but also modulates the number and function of other immune cells. Maximizing in vitro expansion of Bregs and enhancing their regulatory functions are key focuses in transplant immunology. However, the precise mechanisms underlying the in vitro expansion of IL-10-secreting B cells (B10) remain inadequately understood. The present review aims to provide a comprehensive overview of the signaling pathways involved in B10 activation and expansion, as well as to highlight the techniques for in vitro amplification and development of adoptive B10 therapy in transplantation, which aims to advance the field of cellular therapy targeting Bregs.