Chemicals trophic for the thymus: risk for immunodeficiency and autoimmunity.

摘要: The thymus is considered as the priviledged site of T-lymphocyte generation. organ extremely vulnerable to toxic action chemicals. classical example “acute stress-induced involution” mediated by glucocorticoid steroid hormones from adrenal cortex. Nowadays a number substances have been identified that act in differential way on thymus. Examples presented are some organotin compounds acting immature lymphoblasts outer cortex, glucocorticosteroids small thymocytes 2,3,7,8-tetrachlorodibenzo-p-dioxin epithelial cells and cyclosporin dendritic epithelium medulla. mechanisms toxicity include receptor binding (Ah, aryl hydrocarbon receptor; dioxin); CA2+-dependent activation an endogenous endonuclease resulting DNA fragmentation (“programmed cell death” or apoptosis; dioxin glucocorticosteroids); interference with proliferation (some compounds). consequences can be decrease thymic output newly-generated T-lymphocytes (i.e. generation new T-cell repertoire), induction autoimmune symptoms creation unwanted repertoire. This latter phenomenon may applicable under specified conditions induce so-called syngeneic graft-vs-host disease. survey presents brief description function various populations involved. Thereafter susceptibility insults reviewed. Finally, for host defence system, hence health status, considered.