Toll-like receptor ligation for the induction of regulatory B cells.

Toll-like receptors (TLRs) are key components for the recognition of microorganisms, for the initiation of innate immunity, and for promoting adaptive immune responses. TLR signaling in B cells, in addition to B cell receptor or CD40 ligation, plays an important role in B cell differentiation and activation. In contrast, various infectious agents and/or TLR ligands can also prime B cells to induce tolerance and downregulate inflammatory reactions; those B cells are called regulatory B (Breg) cells and are characterized by a dominant IL-10 production. Several studies have suggested that Breg cells are impaired in patients with autoimmune diseases and allergic asthma. However, the role for TLR ligands in the induction of Breg cells as a potential therapy for some of these inflammatory diseases has not yet been investigated. Here, we provide detailed instructions on how to analyze and validate cytokine production in human and mouse B cells in response to various TLR ligands. Furthermore, we describe an assay to investigate the suppressive properties of TLR-induced B cells to confirm their regulatory B cell status.