Ueno Y, Hays E F, Hultin L, Uittenbogaart C H
Department of Microbiology, UCLA School of Medicine 90024.
Cell Immunol. 1989 Dec;124(2):239-51. doi: 10.1016/0008-8749(89)90128-7.
Interleukin-2 receptors (IL-2R) are expressed on minor populations of immature and mature human thymocytes. These studies were designed to determine if immature T cells could respond to the mitogen phytohemagglutinin (PHA-P) plus IL-2 in vitro by increasing the expression of IL-2R and by proliferation. Using monoclonal antibodies to CD5 and magnetic immunobeads we were able to remove all mature, "bright" CD5+ cells from nylon wool-purified thymocytes and to obtain less mature cells which consisted almost completely of cells with the CD4+CD8+ phenotype. These immature cells were mostly "dim" CD5+ and less than 5% CD5- and a small percentage expressed the IL-2R. After culture in serum-free medium with PHA-P, these cells showed only a slight increase in the percentage of IL-2R+ cells and the addition of IL-2 did not increase the percentage of IL-2R+ cells and no proliferation was observed. Unseparated, nylon wool-purified thymocytes contained 14% bright CD5+ cells. These bright CD5+ cells had a mature phenotype of CD4+CD8- (52%) and CD4-CD8+ (27%) cells. A small percentage of these cells were IL-2R+. These bright CD5+IL-2R+ cells were predominantly mature CD4+CD8- cells as measured by three-color flow cytometry. After culture with PHA-P and IL-2, the percentage of IL-2R+ cells increased and they were now found not only on CD4+CD8- but also on CD4-CD8+ and on CD4+CD8+ cells. IL-2 plus PHA-P increased proliferation of these cells as compared to those cultured in medium with PHA-P without IL-2. Thus, we show that human immature thymocytes in contrast to mature thymocytes are not responsive to IL-2 as measured by a lack of IL-2R expression and proliferation. These data indicate that mature thymocytes can express a functional high affinity receptor for IL-2 and suggest that immature thymocytes may not possess a (functional) p75 chain of the IL-2R.
白细胞介素-2受体（IL-2R）在未成熟和成熟的人类胸腺细胞的少数群体中表达。这些研究旨在确定未成熟T细胞在体外是否能通过增加IL-2R的表达和增殖来对丝裂原植物血凝素（PHA-P）加IL-2作出反应。使用抗CD5单克隆抗体和磁性免疫珠，我们能够从尼龙毛纯化的胸腺细胞中去除所有成熟的、“明亮的”CD5+细胞，并获得几乎完全由CD4+CD8+表型细胞组成的不太成熟的细胞。这些未成熟细胞大多是“暗淡的”CD5+，不到5%是CD5-，一小部分表达IL-2R。在含PHA-P的无血清培养基中培养后，这些细胞的IL-2R+细胞百分比仅略有增加，添加IL-2并未增加IL-2R+细胞的百分比，也未观察到增殖。未分离的、尼龙毛纯化的胸腺细胞含有14%的明亮CD5+细胞。这些明亮的CD5+细胞具有CD4+CD8-（52%）和CD4-CD8+（27%）细胞的成熟表型。这些细胞中有一小部分是IL-2R+。通过三色流式细胞术检测，这些明亮的CD5+IL-2R+细胞主要是成熟的CD4+CD8-细胞。在用PHA-P和IL-2培养后，IL-2R+细胞的百分比增加，现在不仅在CD4+CD8-细胞上发现，而且在CD4-CD8+和CD4+CD8+细胞上也发现。与在不含IL-2的PHA-P培养基中培养的细胞相比，IL-2加PHA-P增加了这些细胞的增殖。因此，我们表明，与成熟胸腺细胞相比，人类未成熟胸腺细胞对IL-2无反应，这通过缺乏IL-2R表达和增殖来衡量。这些数据表明成熟胸腺细胞可以表达功能性的高亲和力IL-2受体，并提示未成熟胸腺细胞可能不具有IL-2R的（功能性）p75链。
