The Eye and Immune Privilege
It is often said that the eyes are the window to the soul. But we might also think of the eye as a doorway to medical breakthroughs. This is because the eye has a unique relationship with the body’s immune system. The eye enjoys a special status called immune privilege, making it an ideal environment for researching certain therapies.
What is immune privilege?
When a molecule called an antigen makes its way to a part of the body where it normally doesn’t belong, the body responds by producing antibodies to fight the molecule. This is called an inflammatory response. The immune system kicks in to protect the body from the unrecognized foreign antigen. For example, when a surgeon grafts tissue from one person to another, the body may mount an inflammatory immune response. This can cause the graft to fail.
The eye is one of a few areas of the body with immune privilege. This means that the eye limits its inflammatory immune response in an effort to protect vision. Other sites include the brain, testes, placenta and fetus. Scientists believe immune privilege evolved as a way to protect important areas of the body from possible damage from inflammatory immune response.
Because of this immune privilege, the eye offers an excellent location for certain kinds of research and therapy. For example, scientists can implant types of cells called stem cells in the eye to study their role in regrowing or repairing damaged tissue. Cells implanted in the immune-privileged eye are less likely to be rejected than they might be in other parts of the body.
Another reason the eye is a good place for researching new therapies? It is relatively easy to reach and see inside of the structure. That makes implanting cells in the eye much easier than other areas of the body.