星形胶质细胞抑制T细胞增殖及机制探讨

Mechanisms of inhibiting T-cell proliferation induced by astrocytes

目的初步探讨星形胶质细胞影响T细胞增殖作用及机制。方法利用分离培养小鼠原代星形胶质细胞,以LPS和IFNγ刺激细胞活化,用RTPCR方法检测非活化与活化状态的星形胶质细胞B7.2、B7.1、MHCⅡ和B7H1等免疫分子的表达情况;将不同状态的细胞分别与PHA刺激活化的小鼠T细胞进行共培养,观测其对T细胞增殖的影响,并分析可能的机制。结果小鼠原代星形胶质细胞在非活化状态下组成性表达B7.2和B7H1mRNA,在LPS和IFNγ刺激活化24h后B7H1的表达减少,而同时诱导表达MHCⅡ和B7.1mRNA,而TNFα作用不明显;非活化的星形胶质细胞对PHA刺激活化的T细胞增殖具有明显的抑制作用,而活化的星形胶质细胞的抑制作用减弱。结论小鼠星形胶质细胞在非活化及活化状态下对T细胞增殖具有不同的作用,其机制可能与其表达不同的免疫分子有关。

Objective To investigate the effects of astrocytes on T cell proliferation, and make a preliminary exploration of the mechanisms underlying these effects. Methods Primary cultured mouse astrocytes were activated by 500 ng/ml LPS, 100 U/ml IFN-γ/ and 100 U/ml TNF-α, then the expressions of B7.2, B7.1, MHC Ⅱ and B7-H1 were tested in activated and non-activated astrocytes by RT-PCR. After PHA-activated T cells were co-cultured with the different astrocytes, the T cell proliferation and the expressions of B7.2, B7.1, MHC Ⅱ and B7-H1 were examined. Results B7.2 mRNA and B7-H1 mRNA were constitutively expressed in non-activated mouse astrocytes. MHC Ⅱ and B7.1 mRNA expression was observed and B7-H1 mRNA expression decreased in astrocytes in 24 h after these cells were activated by LPS and IFN-γ, but not TNF-α. In contrast to the weaker effect induced by the activated astrocytes, the non-activated astrocytes had a significant inhibitory effect on PHA-stimulated T cell proliferation. Conclusion Mouse astrocytes under activated and non- activated states have different effects on T cell proliferation, the mechanisms of which may attribute to the expression of different immune molecules in astrocytes.