History and physiology of immune privilege.

Immune privilege is the condition in which selected immune responses are suppressed or excluded in certain organs, such as the eye. Immune privilege in the eye was described over 130 years ago, but its significance was not appreciated until the early 1950s. Investigations beginning in the 1970s ushered in a new era and revealed that ocular immune privilege is due to anatomical, physiological, and immunoregulatory processes that prevent the induction and expression of immune-mediated inflammation. It is widely believed that immune privilege is an adaptation for reducing immune-mediated injury to ocular cells that have limited or no capacity for regeneration.