Sometimes, for an unknown reason, the body is unable to distinguish between self and non self. In a normal immune system; cells that are regarded as self have MHC markers that identify the cell as ‘self’, whilst foreign pathogens will have antigens that the immune system will identify as non-self. In a normal immune response; the body will dispose of the foreign pathogen through either a second or third stage immune response. However, sometimes the body lacks the ability to distinguish between self and non self (i.e it can no longer differentiate between MHC markers which are self and antigens which are non-self); when this occurs cells, that would normally destroy and expose of the pathogen or infected cell, begins to destroy and dispose of cells of non-self. This occurrence is known as a Autoimmune disorder (disease). Whilst the cause is unknown; there are reasons to believe that, due to a genetic factor such as a lacking gene, some sort of genetic factor is the reason for Autoimmune diseases. This is shown through the fact that, on average, autoimmune diseases affect woman more often then men.
Due to the fact that there is no known cause for autoimmune diseases, there is no cure. This means that when a person has an autoimmune disease, the doctors, instead of curing the disease doctors will instead treat the symptoms of autoimmune diseases in order to make the disease more bearable for the patient.
Doctors may also prescribe immunosuppresents in order to reduce the action of the immune system. This reduced function in the immune system leads to a less severe form of the disease due to the immune system not attacking cells that are 'self' as often. This, however offers some negative connotations, with the patient being more susceptible to everyday infections such as the common cold. An example of an autoimmune disease is Grave's disease