免疫系统对自身抗原处于免疫耐受状态,自身耐受的形成主要原因是自身反应性T 细胞克隆在胸腺内被排除,克隆排除发生在胸腺细胞的CD4~+8~+双阳性发育阶段,主要机制在于双阳性胸腺细胞和骨髓衍生的树突状细胞等相互作用,MHC 抗原、TCR 和CD4分子是自身耐受形成的主要参与分子。 Immune system in the self-immune immune tolerance in the state, the main reason for the formation of self-tolerance is self-reactive T cell clones were excluded in the thymus, clonal exclusion occurs in thymocytes of CD4 ~ +8 ~ + double positive development stage, the main Mechanism is that double-positive thymocytes and bone marrow-derived dendritic cells and other interactions, MHC antigens, TCR and CD4 molecules are self-tolerance of the main participating molecules.