The human immune system provides a remarkably robust and broad spectrum of protection against infection and injury. Without this complex response to the presence of foreign materials in our bodies, we would quickly succumb to disease and no longer enjoy protection through vaccinations to diseases such as polio or chicken pox.
Unfortunately, in some individuals, their immune systems target components of their own bodies. When a person’s immune system damages or destroys his or her own cells, then autoimmune disease or autoimmunity occurs. More than 80 autoimmune diseases have been identified where benign immunity progresses to pathogenic autoimmunity that harms the human body.
Autoimmune diseases can harm specific organs or can be systemic, meaning that damage has occurred throughout the body. For example, when the immune system targets insulin-producing organs in the body, type I diabetes occurs, which results in a loss of blood sugar regulation.
A more systemic response occurs in the case of lupus, because the DNA that is normally released into the body when cells naturally die becomes mis-targeted by the immune system, causing skin rash, fever, and other more serious symptoms. This book focuses on three distinct examples of autoimmune disease or reactivity: multiple sclerosis, which involves an autoimmune response against structures that support neurons, rheumatoid arthritis, resulting from autoimmune dependent damage to joints, and organ or graft rejection, which occurs when the immune system recognizes tissues from another individual as foreign.
It is not clear what triggers the progression from normal immune reactivity to autoimmune disease, though in most cases both genetic and environmental factors are thought to be contributing factors. Women are more susceptible than men to develop autoimmune diseases, suggesting some hormonal contributions to disease onset. Most autoimmune diseases are not transmitted from one person to another, but mother-to-child placental transfer is possible. Collectively, autoimmune diseases carry an annual health care cost of over 100 billion dollars in the United States, excluding the cost of organ transplant rejection due to related immunity mechanisms.