Shaw J, Monticone V, Paetkau V
J Immunol. 1978 Jun;120(6):1967-73.
We have partially purified a lymphokine, costimulator, which is necessary to induce mitogenesis in mouse thymocytes in vitro. Costimulator is released from mouse leukocytes exposed to Con A for 12 to 18 hr. It has been purified more than 100 X by gel exclusion chromatography and isoelectric focusing. Thymocytes from CBA/J mice respond to the mitogenic lectin Con A only if the costimulator concentration is above a certain level. Culturing such cells with Con A at a density below 1 X 10(6) cells/ml produces costimulator concentrations too low for mitogenesis. This system has been developed into a quantitative assay for costimulator, to monitor purification, recovery, and biologic activity in various methods of molecular characterization. The activity is trypsin sensitive, and has a buoyant density characteristic of protein or glycoprotein. However, for a protein, it is relatively heat stable. Its m.w., established by carrying out sedimentation, gel filtration, and buoyant density measurements, is 30,500, and its frictional coefficient is 1.45. Costimulator purified by isoelectric focusing is active at 10(-10) M or lower in tissue culture.
我们已经部分纯化了一种淋巴细胞因子——共刺激因子，它是在体外诱导小鼠胸腺细胞有丝分裂所必需的。共刺激因子是从小鼠白细胞中释放出来的，这些白细胞暴露于刀豆蛋白A 12至18小时。通过凝胶排阻色谱法和等电聚焦法，它已经被纯化了100多倍。只有当共刺激因子浓度高于一定水平时，CBA/J小鼠的胸腺细胞才会对有丝分裂原凝集素刀豆蛋白A作出反应。以低于1×10(6)个细胞/毫升的密度将此类细胞与刀豆蛋白A一起培养，产生的共刺激因子浓度过低，无法诱导有丝分裂。该系统已发展成为一种共刺激因子的定量测定方法，用于监测各种分子表征方法中的纯化、回收率和生物活性。该活性对胰蛋白酶敏感，具有蛋白质或糖蛋白的浮力密度特征。然而，作为一种蛋白质，它相对耐热。通过沉降、凝胶过滤和浮力密度测量确定其分子量为30,500，其摩擦系数为1.45。通过等电聚焦纯化的共刺激因子在组织培养中10(-10) M或更低浓度时具有活性。
