Regulatory B cells in autoimmunity: developments and controversies

Over a decade has now passed since the concept of B cells with a regulatory function was resurrected-B cells that produce antibodies with a suppressive effect were first reported in the 1960s and suppressor B cells in the 2000s. In the meantime, some aspects of regulatory B (B-REG)-cell biology have been elucidated. Not only have scientists begun to unravel the mechanism of how B-REG cells suppress immune responses and which cells they target, but their ontogeny and development has also begun to be determined. To date, key roles for B-REG cells have been identified in the regulation of several immune-mediated processes, including autoimmunity and responses to infectious disease and cancer. This Review highlights these advances in the study of B-REG cells, and outlines what is known about their phenotype as well as their suppressive role in autoimmunity from studies in both mice and humans. A particular emphasis is placed on B-REG-cell function in rheumatic diseases.