Isolation and Single-Cell Transcriptomic Analysis of Murine Regulatory B Cells

Regulatory B (Breg) cells have been demonstrated to play an important role in the inhibition of a wide range of immunological responses, and they are absent or malfunction in autoimmune diseases like lupus. Breg cells can control immunological responses and keep the immune system in a balanced state by releasing immunosuppressive cytokines such as transforming growth factor-beta (TGF-β) and interleukin-10 (IL-10), which in turn promote regulatory T (Treg) cells and reduce effector T cell responses. Breg cells have also been linked to the modulation of cancer immunity. Due to their immunosuppressive role, in the context of cancer, Breg cells aid in tumor immune evasion and promote tumor progression. Nonetheless, it has been established that Breg cells are involved in both cancer immunity and autoimmunity, and their characterizations beyond surface markers, for example, on the transcriptomic level, are essential for our understanding of Breg biology in health and disease. In this chapter, using lupus-prone MRL/lpr mice, we describe a Breg cell isolation protocol for the purpose of single-cell RNA sequencing analysis.