Establishment of in vitro experimental model for studying molecular mechanism of self-reactive T cell clone

胸腺内分化途径，T细胞克隆在其随机产生后被选择为个体特异性的TCR库。这一过程对于基于自我和非自我辨别的免疫功能非常重要。我们的项目是解决，以确定的分子机制，调节选择TCR的剧目，通过生产一个发展模型。在这项研究中，我们产生了TCR的转基因小鼠（Tg），这是MHC 11类（I-Ad）限制性和OVA特异性。结合TCR-Tg的T细胞和胸腺基质细胞克隆，我们证明了当OVA-肽被提呈在胸腺和非胸腺基质细胞的I-Ad上时，在体外对DP细胞诱导阴性选择（N.S），表明N.S的基质细胞需要表达选择性MHC，但可以被选择性MHC携带非胸腺衍生细胞取代。对于阳性选择（P.S），包括FTOC在内的个体发生学研究表明，在限制MHC的胸腺环境中，DP细胞上TCR的表达并没有减少，但在不合适的MHC胸腺中，DP细胞上TCR的表达减少。在后者的胸腺细胞中，TCR的表达恢复抗CD 4治疗。这清楚地表明，在DP阶段，TCR的主动下调被TCR介导的信号转导所克服，从而触发P.S过程。

Intrathymic differentiation pathway, T cell clones are selected into TCR repertoires specific for individuals after their random generation. This process is very important for immune functions which are based on discrimination of self and non-self. Our project was addressed to determine the molecular mechanism that regulates the selection of TCR repertoires by producing a developmental model. In this study, we produced transgenic mice (Tg) for TCR which are MHC class 11 (I-Ad) restriced and OVA specific. In combination of T cells from TCR-Tg and a thymic stromal cell clone, we demonstrated that negative selection (N.S) was induced in vitro on DP cells when OVA-peptide was presented on I-Ad of both thymic and non-thymic stromal cells, indicating that stromal cells for N.S required to express selecting MHC but can be substituted by selecting MHC bearing non-thymic derived cells. For positive selection (P.S), ontogenical studies including FTOC showed that TCR expression on DP cells was not redused in thymic environment with restricting MHC but reduced in unappropriate MHC thymus. In the latter thymocytes, TCR expression was recovered by anti-CD4 treatment. Thses clearly demonstrated that the active down regulation of TCR is overcome on DP stage by TCR-mediated signaling which triggeres P.S process.