Miyaji C, Watanabe H, Osman Y, Kuwano Y, Abo T
Department of Immunology, Niigata University School of Medicine, Japan.
Cell Immunol. 1996 May 1;169(2):159-65. doi: 10.1006/cimm.1996.0106.
It is well established that IL-7 supports the earliest differentiation of both T and B cells in fetal and adult life. On the other hand, mature lymphocyte subsets tend to decrease the response to IL-7 in case of T and B cells. In a recent study, NK1.1+ T cells in the thymus are also found to efficiently respond to IL-7 and express IL-7 receptors (IL-7R). This population is generated through an alternative intrathymic pathway. A similar population, namely, T cells with intermediate levels of TCR (i.e., int TCR cells) are known to be generated through extrathymic pathways. In this respect, the proliferative response to IL-7 and the expression of IL-7R in int TCR cells of various organs were compared. Whole liver MNC and isolated int TCR cells from the liver were found to proliferate in response to IL-7. Moreover, a considerable population of int TCR cells in both the liver and thymus were found to carry a higher density of IL-7R on the surfaces than high TCR cells. More precisely, the intensity of IL-7R on int TCR cells in the thymus was the highest but those on int TCR cells in other organs were slightly lower (i.e., int TCR cells in the thymus greater than int TCR cells in the liver greater than high TCR cells). Taken together with the result of expression of IL-7 mRNA by hepatocytes and thymic tissues, it is concluded that IL-7 is one of the most important growth factors for int TCR cells both in the liver and thymus.
众所周知，白细胞介素-7（IL-7）在胎儿期和成年期均支持T细胞和B细胞的早期分化。另一方面，成熟的淋巴细胞亚群在T细胞和B细胞的情况下往往会降低对IL-7的反应。在最近的一项研究中，还发现胸腺中的NK1.1+ T细胞能有效响应IL-7并表达IL-7受体（IL-7R）。这一细胞群体是通过胸腺内的另一条途径产生的。类似的细胞群体，即具有中等水平TCR的T细胞（即int TCR细胞），已知是通过胸腺外途径产生的。在这方面，比较了不同器官的int TCR细胞对IL-7的增殖反应和IL-7R的表达。发现全肝单核细胞（MNC）和从肝脏分离的int TCR细胞对IL-7有增殖反应。此外，发现肝脏和胸腺中的大量int TCR细胞表面携带的IL-7R密度高于高TCR细胞。更确切地说，胸腺中int TCR细胞上的IL-7R强度最高，但其他器官中int TCR细胞上的IL-7R强度略低（即胸腺中的int TCR细胞大于肝脏中的int TCR细胞大于高TCR细胞）。结合肝细胞和胸腺组织中IL-7 mRNA表达的结果，可以得出结论，IL-7是肝脏和胸腺中int TCR细胞最重要的生长因子之一。
