Together with signaling through CD40, B cells respond to IL‐10 by altering their production of IgM, IgG1 and IgG3.34 Indeed, most B cells, including some of those affected by MS disease and altered by alemtuzumab therapy, expressed lower levels of CD40, a well‐known MS risk gene.35 The gene discussed is IGHG3; the disease is myeloid sarcoma.