Myelin is a fatty material that coats, protects, and insulates nerves, enabling them to quickly conduct impulses between the brain and different parts of the body. Myelin also contains proteins that can be targeted by the immune system.Myelin coats the nerves of both the central nervous system and the peripheral nervous system; the destruction of the myelin in the central nervous system is what triggers many of the symptoms of multiple sclerosis (MS). cells from the body's own immune system attack and destroy the myelin sheath Click to view larger image. In multiple sclerosis, T cells from the body's own immune system attack and destroy the myelin sheath, leaving the nerve cell fibers unprotected.