Influence of immune surveillance and immune privilege on formation of intraocular tumors.

The immune surveillance theory proposed almost half a century ago stated that the immune system was responsible for preventing the formation of spontaneous tumors by identifying and eliminating neoplastic cells early in their development. Recent studies demonstrating that innate and adaptive immune effector cells participate in preventing tumor growth and are effective in reducing the frequency of tumors have revived interest in immune surveillance. Paradoxically, other recent studies demonstrate that the immune system can also promote tumor progression by altering the immunogenic phenotype of developing tumors in a process called immunoediting. These data raise new questions regarding whether immune surveillance and immunoediting occur within the immune-privileged ocular environment where the innate and adaptive immune effector cells are inhibited and/or participate in the development of regulatory T cells.