Takács L, Ruscetti F W, Kovacs E J, Rocha B, Brocke S, Diamantstein T, Mathieson B J
Laboratory of Molecular Immunoregulation, National Cancer Institute, Frederick, MD 21701-1013.
J Immunol. 1988 Dec 1;141(11):3810-8.
IL-2R alpha-chain is expressed on a subset of mouse CD4- and CD8-, double negative (DN) thymocytes. This expression of IL-2R alpha-chain on some DN thymocytes in the mouse has led to the proposal that IL-2 might serve as a principal growth and/or differentiation factor for immature thymocytes. However, previous histologic observations have indicated that IL-2R alpha-chain is not expressed on the subcapsular thymic blasts (an area rich in DN cells) in either huma or rat thymus, whereas all three species display IL-2R expression on a few cells in the thymic medulla. Therefore, we characterized rat DN thymocytes to determine whether they contained an IL-2R+ population. The results show that rat thymic DN cells share several characteristics with mouse DN cells. However, most of the rat strains do not express the IL-2R on DN cells as shown either by immunofluorescence or by IL-2 binding and receptor cross-linking. Thus, the rare medullary IL-2R+ cells were not found in the DN cells. Only in the exceptional F344 rat strain is the IL-2R alpha-chain expressed on a major proportion of thymocytes, including both DN cells and small cortical-type thymocytes. Furthermore, rat DN cells do not contain detectable IL-2 mRNA or cytoplasmic IL-2 activity, thus supporting the conclusion that it is unlikely that IL-2 and IL-2R serve to maintain the proliferation of rat DN thymocytes in vivo. The possible significance of in vivo expression of IL-2R alpha-chain on immature thymocytes in the mouse and in a single rat strain is discussed.
白细胞介素-2受体α链在小鼠CD4和CD8双阴性（DN）胸腺细胞的一个亚群上表达。小鼠中某些DN胸腺细胞上白细胞介素-2受体α链的这种表达导致了这样一种观点，即白细胞介素-2可能作为未成熟胸腺细胞的主要生长和/或分化因子。然而，先前的组织学观察表明，在人类或大鼠胸腺的被膜下胸腺母细胞（富含DN细胞的区域）上不表达白细胞介素-2受体α链，而在这三个物种的胸腺髓质中的少数细胞上均显示有白细胞介素-2受体表达。因此，我们对大鼠DN胸腺细胞进行了特征分析，以确定它们是否含有白细胞介素-2受体阳性群体。结果表明，大鼠胸腺DN细胞与小鼠DN细胞具有一些共同特征。然而，如免疫荧光或白细胞介素-2结合及受体交联所示，大多数大鼠品系的DN细胞不表达白细胞介素-2受体。因此，在DN细胞中未发现罕见的髓质白细胞介素-2受体阳性细胞。只有在特殊的F344大鼠品系中，白细胞介素-2受体α链才在包括DN细胞和小皮质型胸腺细胞在内的大部分胸腺细胞上表达。此外，大鼠DN细胞不含有可检测到的白细胞介素-2 mRNA或细胞质白细胞介素-2活性，从而支持了这样的结论，即白细胞介素-2和白细胞介素-2受体不太可能在体内维持大鼠DN胸腺细胞的增殖。本文讨论了小鼠和单一大鼠品系中未成熟胸腺细胞上白细胞介素-2受体α链体内表达的可能意义。
