Sprecher E, Giloh H, Rahamim E, Yefenof E, Becker Y
Department of Molecular Virology, Faculty of Medicine, Hebrew University, Jerusalem, Israel.
Leuk Res. 1989;13(9):799-809. doi: 10.1016/0145-2126(89)90093-3.
The thymus is populated by various Ia+ cell populations, including epithelial cells, macrophages and dendritic cells. Thymic cell suspensions were stained with an anti-Ia antibody and shown by cytofluorometry to contain a small number of strongly Ia+ cells characterized by a large diameter. The cell population was separated with the aid of the fluorescence-activated cell sorter (FACS) and characterized. They were shown to express high levels of membranal Ia antigens; they demonstrated ATPase activity and displayed the ultrastructural features characteristic of the previously described thymic interdigitating cells. C57BL/6 mice were submitted to various regimens of X-irradiation. Whereas exposure to a single dose of X-irradiation was followed by an increase in the percentage of strongly Ia+ cells, exposure to a leukemogenic regimen of fractionated X-irradiation led to a decrease in the percentage and absolute numbers of these cells in the thymus. Of the C57BL/6 mice that were irradiated with fractionated X-irradiation, 77% developed leukemia. Intravenous injection of syngeneic bone marrow one day following the last irradiation or protection of the femur during irradiation prevented both the appearance of leukemia and the disappearance of interdigitating cells. Therefore an inverse correlation between the presence of thymic dendritic cells and the incidence of leukemia in C57BL/6 mice could be demonstrated. These findings are discussed in relation to the putative role of dendritic cells in the thymus.
胸腺中存在多种Ia⁺细胞群体，包括上皮细胞、巨噬细胞和树突状细胞。用抗Ia抗体对胸腺细胞悬液进行染色，通过细胞荧光测定法显示其中含有少量直径较大的强Ia⁺细胞。借助荧光激活细胞分选仪（FACS）分离并鉴定了该细胞群体。结果表明它们表达高水平的膜Ia抗原；它们具有ATP酶活性，并呈现出先前描述的胸腺交错突细胞的超微结构特征。对C57BL/6小鼠进行了不同方案的X射线照射。单次X射线照射后，强Ia⁺细胞的百分比增加，而接受分次X射线照射的致白血病方案后，胸腺中这些细胞的百分比和绝对数量均减少。在接受分次X射线照射的C57BL/6小鼠中，77%发生了白血病。在最后一次照射后一天静脉注射同基因骨髓或在照射期间保护股骨，可预防白血病的出现和交错突细胞的消失。因此，可以证明C57BL/6小鼠中胸腺树突状细胞的存在与白血病发病率之间呈负相关。结合树突状细胞在胸腺中的假定作用对这些发现进行了讨论。
