Immune privilege

Certain sites of the mammalian body have immune privilege (no immune response), meaning they are able to tolerate the introduction of antigens without eliciting an inflammatory immune response. Tissue grafts are normally recognised as foreign antigens by the body and attacked by the immune system. However, in immune privileged sites, tissue grafts can survive for extended periods of time without rejection occurring. Immunologically privileged sites include:

It’s thought that immune privilege also occurs to some extent—-or is able to be induced in—-articular cartilage. it was once thought that, theoretically, it could also occur (or be inducible) in the brain, but this is now known to be incorrect, as it has been shown that immune cells of the central nervous system contribute to the maintenance of neurogenesis and spatial learning abilities in adulthood.

Immune privilege is thought to be an evolutionary adaptation to protect vital structures from the potentially lethal effects of an inflammatory immune response in those regions. Inflammation in the brain or eye could cause the loss of organ functions, while immune responses directed against a fetus could cause miscarriage.

Immune privilege allows doctors to perform cornea transplants and knee meniscal transplantation.

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