Function of thymic stroma cells on normal hematopoietic cells and malignant cells

在胸腺基质细胞的许多功能中，前胸腺细胞向胸腺迁移的作用尚不清楚。胸腺基质细胞分泌趋化因子，将骨髓细胞移入胸腺。在短期培养的大鼠胸腺上清液中，趋化活性恢复，而在肾脏和肝脏上清液中，趋化活性未恢复。在许多品系的幼龄大鼠和老年BUF大鼠胸腺中均检测到该活性。用ficol-paque分离，反应的骨髓细胞密度为1.077。骨髓细胞的反应性在各大鼠品系之间存在差异，反应性最强的品系为BUF。趋化因子被认为在胸腺肿瘤、胸腺淋巴瘤和胸腺瘤的诱导和病理状态中有一定的作用。大鼠胸腺淋巴瘤原发肿瘤细胞和已建立的细胞系均对该因子有反应。转移到胸腺的肿瘤细胞比原移植部位生长的肿瘤细胞反应性更强，说明该因素也影响淋巴瘤细胞的转移过程。为了纯化该因子，测试了各种色谱介质；对凝胶过滤、DEAE sepharose和疏水丁基sepharose有效，但对4种凝血素、肝素、羟基磷灰石、5种染料和疏水醚-sepharose柱无效。另一方面，编码该因子的基因被认为是决定胸腺淋巴瘤发生敏感性的基因之一。用BUF、WKY及其杂交后代对n -亚硝基源性胸腺淋巴瘤发生进行遗传分析。结果，发现了一个与Gc基因（编码维生素D结合蛋白）相连的决定潜伏期的基因（暂时为TIs-3）。然而趋化因子与趋化因子之间的联系尚不清楚。胸腺淋巴瘤易感性与趋化因子的关系有待进一步研究。

In many functions of thymic stroma cells, roles on migration of prothymocytes into the thymus is not well understood. It is considered that thymic stromal cells secret chemotactic factors to immigrate bone marrow cells into the thymus. Chemotactic activity was recovered in supernatant fluid of short term cultured rat thymus but not in that of the kidney and liver. This activity was detected in the thymus of young rats of many strains and old BUF rats. Reacting bone marrow cells present in 1.077 density fraction when separated with ficol-paque. Reactivity of bone marrow cells was different among rat strains and most reactive strain was BUF.Chemotactic factor was thought to have some roles on induction and pathological state of thymic tumors, thymic lymphoma and thymoma. Rat thymic lymphoma cells of primary tumor and established cell lines all reacted to this factor. Tumor cells that metastasized to the thymus is more reactive than that grew at primarily transplanted site, meaning that this factor also influence on metastasis process of lymphoma cells. For the purification of this factor, various medias for chromatography were tested ; effective for gel filtration, DEAE sepharose, and hydrophobic butyl-sepharose, but ineffective for columns of 4 rectins, heparin, hydroxyapatite, 5 dyes, and hydrophobic ether-sepharose. On the other hand, the gene coding this factor is thought to be one of genes determining sensitivity of thymic lymphomagenesis. Genetic analysis in N-nitrosourea-thymic lymphomagenesis was carried out with BUF,WKY,and their cross offspring. As a result, one gene determining latent period (temporarily TIs-3), whcih links to the Gc gene (coding vitamin D binding protein), was identified. However, linkage between chemotactic factor is still obscure. Relationship between susceptibility for thymic lymphomagenesis and chemotactic factor should be investigated further.