Functional status of interleukin 2 receptors expressed by immature (Lyt-2-/L3T4-) thymocytes.
Functional status of interleukin 2 receptors expressed by immature (Lyt-2-/L3T4-) thymocytes.
复制标题
未成熟 (Lyt-2-/L3T4-) 胸腺细胞表达的白细胞介素 2 受体的功能状态。
作者：
J. Lowenthal;R. Howe;R. Ceredig;H. Macdonald
表型未成熟(Lyt-2-/L3T4-)胸腺细胞亚群表达多肽激素白介素2(IL-2)受体；然而，这些细胞在体外不能对IL-2作出反应。在更详细地研究这一现象时，我们观察到新鲜分离的未成熟胸腺细胞上的IL-2受体(IL-2-R)与IL-2的亲和力(Kd约为100 pm)比激活的成熟T细胞和T细胞系上的IL-2-R低约5倍(Kd约为20 pm)。此外，与激活的T细胞不同，Lyt-2-/L3T4-胸腺细胞不内吞结合IL-2。在佛波酯(PMA)和钙离子载体联合短期培养时，Lyt-2-/L3T4-胸腺细胞以很大程度上依赖于IL-2的方式增殖。IL-2-R在这些活化细胞上的表达最初消失(24小时)，随后重新出现(48~72小时)。在活化的胸腺细胞上重新表达的IL-2-R与成熟T淋巴细胞上的相似之处在于，它们以高亲和力(Kd=15~25 pm)结合IL-2，并能够内吞IL-2。综上所述，这些数据限制了IL-2在胸腺内生长调节中的可能生理作用。
A subpopulation of phenotypically immature (Lyt-2-/L3T4-) thymocytes express receptors for the polypeptide hormone interleukin 2 (IL 2); however, these cells do not proliferate in vitro in response to IL 2. In investigating this phenomenon in greater detail, we observed that the IL 2 receptors (IL 2-R) on freshly isolated immature thymocytes bound IL 2 with about fivefold lower affinity (Kd approximately 100 pM) than IL 2-R on activated mature T cells and T cell lines (Kd approximately 20 pM). Furthermore, in contrast to activated T cells, Lyt-2-/L3T4- thymocytes did not endocytose bound IL 2. When stimulated in short-term culture with a combination of phorbol ester (PMA) and calcium ionophore, Lyt-2-/L3T4- thymocytes proliferated in a largely IL 2-dependent fashion. IL 2-R expression on these activated cells initially disappeared (at 24 hr) and subsequently reappeared (at 48 to 72 hr). Reexpressed IL 2-R on activated thymocytes resembled those on mature T lymphocytes in that they bound IL 2 with high affinity (Kd = 15 to 25 pM) and were capable of endocytosing IL 2. Taken together, these data place certain constraints on the putative physiologic role of IL 2 in intrathymic growth regulation.