Science of Autoimmunity
The immune system, the body’s defense against invading pathogens and abnormal/damaged cells, is a complex web of interacting factors, each with multiple effects on other components of the system. Activation of any one component initiates cascading responses “downstream” along multiple pathways, with each pathway having its own specialized functions. Ordinarily, this finely tuned mechanism operates with high efficiency, protecting us against viral, bacterial, and fungal infections, and eliminating or controlling cancerous cellular transformations. However, in this intricate and inter-dependent system, even small aberrations in the functioning of a single component can have significant ripple effects, derailing normal immune responses.
One consequence of aberrant changes that lead to abnormally overactive immune responsiveness is autoimmune disease. As a result of uncontrolled immune activity, defensive responses that are usually protective become potentially dangerous, targeting the body’s normal cells. More than 800 autoimmune diseases have been identified, including a variety of common debilitating conditions, such as multiple sclerosis (MS), systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), Sjogren’s syndrome, psoriasis, and scleroderma.
Initiation of the excessive immune responsiveness characteristic of autoimmune diseases can be triggered by microbes and, under certain circumstances, by the body’s own molecules, particularly DNA, RNA, and related immune complexes. Several genes have been found to increase the risk of autoimmune responses developing, with a greater likelihood of autoimmune diseases seen in particular racial/ethnic groups and in women.