The role thymic epithelial cell on induction of tolerance to the allografts : Analysis of immuno-modulatory T cell

小鼠表皮细胞与胸腺上皮细胞具有惊人的细胞学相似性，但在普通培养基中不增殖，据报道在缺钙培养基中生长。因此，采用缺钙培养基培养小鼠胸腺，成功地从小鼠胸腺中获得上皮细胞系IT- 76MHC（在常规培养基中，在低钙培养基中为IT- 76m）。结果表明，IT-76MHC细胞为小鼠胸腺上皮细胞：1)嵌合状排列，2)存在发育良好的桥粒和3)张力丝，4)细胞角蛋白阳性。研究已建立小鼠胸腺上皮细胞功能的实验已经部分进行，发现细胞上清中存在IL-3和集落刺激活性，提示胸腺上皮细胞可能通过其因子作为早期胸腺细胞的生长促进剂。使用几种神经内分泌家族表位抗体对IT-76MHC进行免疫组织化学研究。免疫反应性催产素、抗利尿激素、胰岛素样生长因子（IGF） 1和2通过胸腺上皮细胞系表达。这些结果表明可以在分化的T细胞系统前呈递代表神经内分泌家族的自身抗原。

Mouse epidermal cells, which have a surprising cytological resemblance to thymic epithelial cells but do not proliferate in an ordinary medium, were reported to grow in a calcium-depleted medium. Therefore, the calcium-depleted medium was applied for the culture of the mouse thymus, and successfully, an epithelial cell line, IT- 76MHC (in regular medium ; in low Ca medium, it is IT-76M) was obtained from the mouse thymus. IT-76MHC cells were identified as distinct mouse thymic epithelial cells by 1) mosaic-like arrangement, 2)presence of well-developed desmosome and 3) tonofilaments, and 4) positivity for cytokeratin. Experiments to investigate functions of established mouse thymic epithelial cells have been partly carried out, and IL-3 and colony-stimulating activities were found to be present in the supernatant of the cells, suggesting that thymic epithelial cells may act as a growth promoter for early thymocytes through their factors. Immunohistochemistry studies were performed on IT-76MHC using several antibodies to the epitops of neuroendocrine families. Immunoreactive oxytocin, vasopressin, insulin-like growth factor (IGF) 1 and 2 are expressed by thymic epithelial cell line. These results suggest that could present self antigens representing the neuroendocrine family in front of the differentiating T cell system.