immune privileged siteJoe Segen2016-12-25T03:58:46+00:00
immune privileged site
A site in the body in which antigen-T cell interactions facilitate immune tolerance as opposed to immune destruction, which is the norm in non-privileged sites.
Mechanisms of immune privilege
• Physical–paucity or absence of lymphatics
• Low expression of classical MHC class Ia antigens
• High expression of immunoregulatory nonclassical, MHC class Ib antigens
• Overexpression of surface molecules that inhibit complement activation
• Local production of immunosuppressive cytokines–e.g., TGF-β
• Expression of Fas ligand that controls Fas-expressing cell entry
Sites of immune privilege Eye, placenta and fetus, testis; the brain was formerly regarded as a site of immune privilege.