Acknowledgements

The testis in immune privilege Summary: The production, differentiation, and presence of male gametes represent inimitable challenges to the immune system, as they are unique to the body and appear long after thematuration of the immune system and formation of systemic self-tolerance. Known to protect germ cells and foreign tissue grafts from autoimmune attack, the ‘immune privilege ’ of the testis was originally, and somewhat simplistically, attributed to the existence of the blood–testis barrier. Recent research has shown a pre-viously unknown level of complexity with a multitude of factors, both physical and immunological, necessary for the establishment and maintenance of the immunotolerance in the testis. Besides the blood– testis barrier and a diminished capability of the large testicular resident macrophage population to mount an inflammatory response, it is the constitutive expression of anti-inflammatory cytokines in the testis by immune and particularly somatic cells, that represents an essential elemen