JL he eye and the immune system represent discrete organ systems in vertebrates. Each possesses a unique and vital function that ensures the viability of the host, and loss of either or both brings disease and death. For many years, it has been known that the eye and the immune system are joined in a curious phenomenon called "immune privilege." This phenomenon was first described experimentall...

The term "immune privilege" was originally coined to describe the suppression of inflammatory responses within organs protected by anatomic barriers, ie, the eyes, brain, placenta, and testes. However, cellular and metabolic processes, which orchestrate immune responses, also control inflammation within these sites. Our current understanding of tolerogenic mechanisms has extended the definition...

The term "immune privilege" was coined to describe weak immunogenicity (hypo-immunity) that manifests in some transplant settings. We extended this concept to encompass hypo-immunity that manifests at local sites of inflammation relevant to clinical diseases. Here, we focus on emerging evidence that enhanced tryptophan catabolism is a key metabolic process that promotes and sustains induced imm...

The mammalian testis belongs among a small number of tissues that can unambiguously be called “immunologically privileged,” as demonstrated by the ability to tolerate not only testicular autoantigens but also alloand xenoantigens experimentally located within the testis environment. The mechanisms underlying this privilege remain poorly understood compared with more intensively studied models o...

Alopecia areata is considered to be a cell-mediated autoimmune disease, in which autoreactive cytotoxic T cells recognize melanocyte-associated proteins such as tyrosinase. This review discusses recent advances in the understanding of the pathogenesis of alopecia areata, focusing on immunobiology and hormonal aspects of hair follicles (HFs). The HF is a unique "miniorgan" with its own immune an...

The genesis of immune privilege high in the evolutionary tree suggests that immune privilege is necessary, if not advantageous for the progressive development of the CNS. Upon reaching a certain degree of complexity, it seems as if the CNS was obliged to restrain the immune system from penetrating the blood-brain barrier. CNS autoimmunity against myelin proteins is known to be a contributory fa...