Progress in mechanisms of peripheral immunological tolerance

During the development of T lymphocytes,most of self-reactive T lymphocytes are deleted by negative selection in thymus,but there are still a few of them escaped to peripheral lymph organs.The function of peripheral immunological tolerance is to inhibit and restrict the reactivity of self-reactive T lymphocytes escaped from thymus in the periphery.There are various mechanisms participate the maintenance of peripheral immunological tolerance,including clone deletion,clonal anergy,immunological ignorance,immunosuppression of Treg,tolerogenic DCs,etc.Once peripheral immunological tolerance is broken down,it will cause autoimmune reaction and severe autoimmunity.