How humans beat auto-immune disease revealed

Washington: Scientists claim to have found how the human body protects itself against the "friendly fire" from its immune system, known as auto-immune disease, a major finding that may pave the way for better treatments for autoimmune conditions like diabetes and rheumatoid arthritis.
An international team, led by the Australian National University, has revealed the human body incorporates multiple fail-safe mechanisms to protect itself against the autoimmune disease, the `Proceedings of the National Academy of Science`
journal reported.
"Why the immune system sometimes attacks different parts of our body is still poorly understood. Consequently, no specific prevention or treatment is yet available," according to Charis Teh, who led the study.
The scientists focused their work on understanding the progress of a condition caused by single genetic defect, Autoimmune Polyendocrine Syndrome 1.
People with this disease often seem perfectly healthy before the first vital organ is attacked, usually in childhood. Then come attacks on additional organs. Different organs are affected in different people, and the age when problems begin varies.
By studying a mouse strain incorporating an equivalent gene defect, the scientists discovered that the immune system is engineered with a series of back-up systems against such friendly fire, like multiple layers of armour.

Normally, any immune cells that could attack organs in the body are eliminated within the thymus gland where they develop, before they are released into the bloodstream. In the mice with the Autoimmune Polyendocrine Syndrome 1 gene defect, this does not happen.
Despite this, the mice remain healthy, because a backup mechanism steps in to disable the ability of the rogue cells to launch an attack on the body’s tissue.
But when this backup mechanism is crippled by introducing a second genetic change, the mice succumb to a disastrous immune attack. Even then, many organs are still not attacked, suggesting they are protected by additional backup
systems, say the scientists.