B Cells as Regulators

B lymphocytes have a unique capacity to produce antibodies and are important antigen-presenting cells. In addition to these primary functions, they can secrete cytokines and subsequently influence immunity in a non-antigen-restricted manner. Through these activities, B cells can act as drivers and regulators of immune responses. B cell-mediated regulatory activities primarily involve their production of antiinflammatory cytokines such as interleukin (IL)-10 and IL-35. Through production of these factors, B cells can protect from autoimmune disease and limit host resistance to pathogens. Here, we review current data on the suppressive activities of B cells, using several examples of autoimmune or inflammatory disorders, and infectious diseases in mice. We also discuss available data on the phenotype and function of human IL-10-producing B cells. Finally, we detail throughout the text the recently identified relationship between IL-10-producing B cells and antibody-secreting cells, which demonstrates that plasmablasts/plasma cells can have antibody-independent functions.