 Multiple sclerosis, MS, is thought to be caused by an immune system attack on the central nervous system. Current treatments for MS target the immune system, but they can also affect other parts of the body. Recent research has shown that these treatments can also reduce the number of certain types of white blood cells, such as CD19+, and CD27+, memory B cells. These cells are important for maintaining the immune system's ability to fight off infections. By reducing their numbers, these treatments may help to slow down the progression of MS. This article was authored by David Baker, Monica Marta, Gareth Price, and others.