Immortalized B cells: a neverending source of antigen-presenting cells for vaccines?

Abstract

Evaluation of: Wiesner M, Zentz C, Mayr C et al. Conditional immortalization of human B cells by CD40 ligation. PLoS ONE 3(1), e1464 (2008).Cellular adjuvants have recently been studied as tools to induce immune responses and thus to control malignancies. They are, therefore, subject to intensive research in the field of tumor immunotherapy and immunology. In particular, dendritic cells have been shown to efficiently present antigens to T cells and, thus, induce primary and secondary immune responses. Nevertheless, dendritic cell-based clinical applications are challenged by their low frequency, inability to grow in culture and, also, lack of purity. Among other alternatives, CD40-activated B cells have previously been shown to efficiently present antigens and be expandable for several weeks, rendering them an interesting alternative to induce anti-tumor immune responses. Immunological tumor control probably warrants life-long vaccination, emphasizing the need for large amounts of cells. Furthermore, for regulatory reasons, homogenous, well-characterized master cell lines would be ideal to reduce the cost and technical challenges of cellular vaccines. The paper under evaluation introduces the concept that B cells activated via CD40 and IL4 receptor signaling can be expanded for more than 100 doublings to almost unlimited numbers, suggesting that they are conditionally immortalized. Such cells are shown to remain good antigen presenters and, therefore, are a most interesting cellular adjuvant for immunotherapy.