b'Your immune system is meant to protect you. But when you have MS, your immune system can seem like your worst enemy. Understanding what goes wrong in the immune system of a person with MS, how medications can help, and how best to support a healthier immune system is vital to living well with the condition. In this years National Multiple Sclerosis Education and Awareness month activities, we provide a deeper understanding of the immune system, discuss the benets and advances in treatment, and highlight how you can advocate for autoimmune research in your community. We hope this theme will empower you to take charge of the factors in your control that contribute to a healthy, balanced immune system and join in with the larger autoimmune disease community in ghting for answers. Sincerely,The MS Focus Team MS and the Immune System: What goes wrong? The human immune system is incredibly complex. It is made up of both cells and chemical messengers (called cytokines) that allow for communication between immune cells. When working appropriately, the immune system is highly regulated and has a balance between inammatory and anti-inammatory actions. So what goes wrong in MS?Your immune system is designed to ght off outside invaders. Outside invaders are any germs (i.e., bacteria, viruses, fungi, or toxins) that can cause harm to your body. With MS, your immune system mistakenly identies the myelin sheath (a layer of insulation around your nerves) as a foreign invader. Once this process starts, your body will start trying to ght off the invader and create inammatory cells that damage the myelin sheath. This repetitive ght leads to scar tissue forming around your nerves. Normally, the central nervous system is selective about what immune cells can enter. The blood-brain barrier helps protect the human brain from potentially damaging inammatory cells, chemicals, and other substances. In MS, the blood-brain barrier becomes leaky, allowing inammatory cells from the immune system to cross into the brain and spinal cord.Why do they do this? Its thought that cells inside the central nervous system, called glia, become activated and secrete cytokines that serve as a homing signal for these inammatory cells. The blood-brain barrier is less effective in a person with MS at keeping these inammatory cells out. We do not yet know what turns on these glial cells in the rst place.Some of the cells involved in the immune attack on the central nervous system include T-cells, B-cells, and macrophages. T-cells can be further divided into classes called CD4 and CD8 cells. CD4 cells can be further divided into cells called Th1, 2'