B cells can control responses of myeloid cells through the release of particular cytokines (small proteins that control the growth and activity of cells in the immune system), challenging the prevailing view that T cells are the principle orchestrators of immune responses. In individuals with Multiple Sclerosis (MS), abnormally active respiration in B cells drives pro-inflammatory responses of myeloid cells and T cells, leading them to attack the protective sheath (myelin) that covers nerve fibers, and leading to nerve damage that causes symptoms of MS.