MS is an autoimmune disease — but what is an autoimmune disease?
The human body runs by keeping very delicate balances. While many different systems carry out their own functions internally, they also adapt to the processes running in other systems, together forming a whole. We could actually liken this to a factory. This factory is made up of its own sub-units for generating power, cooling, storage, processing materials, transport and much more — but the ultimate purpose of all of them is to cooperate so that the factory can do its job.
One of the many systems at work in the human body is the immune system. In fact, from the very first moment we come out of the womb into the outside world, our body is not alone. Microorganisms of many kinds, large and small (bacteria, viruses and others), begin to enter our body. Some bacteria settle in certain regions and start to live with us; in doing so they both stay alive themselves and bring various benefits to the body they inhabit (commensalism). But not all microorganisms are well-meaning. Some are bent on attacking and destroying the body they enter. For exactly this reason, if our body could not mount a good defence against these hostile organisms, it could not sustain its functions or its life.
The immune system, in fact, works quite cleverly. It operates essentially in two different ways. The first, the innate immune system, recognizes every microorganism regardless of type and tries to destroy it. The second is the adaptive immune system. Once this system has met an invader, it commits it to memory and produces cells that make it ready for the next encounter. In this way it can put up a far more effective defence the next time. Vaccines, in fact, work this way too. If this system works well, a person can successfully fend off these invasions throughout life and carry on living.
Sometimes, however, this system loses its way and, alongside the small invaders, starts to react to the body’s own cells, mistaking them for foreign. Although it is not exactly known why this happens, it can one day arise as a result of hereditary traits passed down from mother and father together with the environmental conditions a person lives in. To give examples of such diseases: if the target cell is, say, the insulin-producing islet cells in the pancreas, then diabetes; if it is the synovial cells in our joints, rheumatoid arthritis; or if it is the pigment cells in our skin, conditions like vitiligo. It is precisely because the immune system reacts to the body’s own cells that these are named auto- (self) immune diseases.
MS, too, is an autoimmune disease of this kind. When immune cells react to cells in the brain and spinal cord that they ought not to react to, tiny areas of inflammation (plaques) form and cause certain neurological signs and symptoms in the person. Let me also add that, besides MS, there are many autoimmune diseases that affect the nervous system.