Testis immune privilege - Assumptions versus facts

ABSTRACT

The testis has long enjoyed a reputation as a n immunologically privileged site based on its ability to protect auto - antigenic germ cells and provide an optimal environment for the extended survival of transplanted allo - or xeno - grafts. Exploration of the role of anatomical, physiological, immunologica l and cell ular components in testis immune privilege reveal ed that the tolerogenic environment of the test i s is a result of the immunomodulatory factors expressed or secreted by testicular cells (mainly Sertoli cells, peritubular myoid cells, Leydig cells , and resident macrophages ). The b lood - testis barrier/Sertoli cell barrier, is also important to seclude advanced germ cells but its requirement in testis immune privilege needs further investigation . T esticular immune privilege is not permanent , as an effe ctive immune response can be mounted against transplanted tissue , and bacterial/viral infections in the testis can be effectively eliminated . Overall, the cellular components control the fate of the immune response and can shift the response from immunodestructive to immunoprotective, resulting in immuneprivilege.