Self and Non-self
The key to a healthy immune system is its remarkable ability to distinguish between the body’s own cells, recognized as 'self,' and foreign cells, or 'non self.' The body’s immune defences usually live side by side with each others cells that carry distinctive 'self' marker molecules. But when immune defenders come face to face with unrecognisable cells or organisms carrying markers that say 'non self,' they quickly launch an attack.
Anything that can wake up and trigger this immune response is called an antigen. An antigen can be a microbe such as a virus, or a part of a microbe such as a molecule. Tissues or cells from another person (except an identical twin) also carry nonself markers and act as foreign antigens. This explains why tissue transplants may be rejected.
In different situations, the immune system can mistake self for nonself and launch an attack against the body’s own cells or tissues. The result is called an autoimmune disease. Some forms of arthritis and diabetes are autoimmune diseases.
The key to a healthy immune system is its remarkable ability to distinguish between the body’s own cells, recognized as 'self,' and foreign cells, or 'non self.' The body’s immune defences usually live side by side with each others cells that carry distinctive 'self' marker molecules. But when immune defenders come face to face with unrecognisable cells or organisms carrying markers that say 'non self,' they quickly launch an attack.
Anything that can wake up and trigger this immune response is called an antigen. An antigen can be a microbe such as a virus, or a part of a microbe such as a molecule. Tissues or cells from another person (except an identical twin) also carry nonself markers and act as foreign antigens. This explains why tissue transplants may be rejected.
In different situations, the immune system can mistake self for nonself and launch an attack against the body’s own cells or tissues. The result is called an autoimmune disease. Some forms of arthritis and diabetes are autoimmune diseases.