Schwarting R, Welte K, Chiorazzi N, Ralph P, Lane C L, Long C, Wang C Y
Eur J Immunol. 1985 Jun;15(6):632-7. doi: 10.1002/eji.1830150619.
B cell stimulatory factor (BSF) activity was generated over a period of five days by phytohemagglutinin-stimulated E rosette-positive peripheral blood lymphocytes. This activity was subjected to a multistep purification procedure including ammonium sulfate precipitation, anion-exchange chromatography, gel filtration, procion red-agarose chromatography and reverse phase high performance liquid chromatography (RP-HPLC). The last purification step dissected BSF activity into two active fractions, one corresponded to the interleukin 2 (IL 2) activity whereas the other active fraction was free of IL 2 activity. Preparative isoelectric focusing analysis defined isoelectric points of pH 7.2 for both BSF and IL 2. Molecular weight analysis of BSF was carried out by preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. BSF activity was eluted from gel strips corresponding to a molecular mass of 16 and 17 kDa. The 16-kDa fraction was free of IL 2 activity whereas the 17-kDa fraction overlapped with IL 2. Since recombinant IL 2 was capable of exhibiting significant BSF activity in anti-IgM or Staphylococcus aureus Cowan strain I-dependent assay systems, it cannot be excluded that IL 2 itself is a BSF. Nevertheless these studies demonstrate the existence of a BSF free of IL 2 activity.
植物血凝素刺激的E花环阳性外周血淋巴细胞在五天时间内产生了B细胞刺激因子（BSF）活性。该活性经过多步纯化程序，包括硫酸铵沉淀、阴离子交换色谱、凝胶过滤、普施安红琼脂糖色谱和反相高效液相色谱（RP-HPLC）。最后一步纯化将BSF活性分离为两个活性组分，一个对应白细胞介素2（IL-2）活性，而另一个活性组分不含IL-2活性。制备性等电聚焦分析确定BSF和IL-2的等电点均为pH 7.2。通过制备性十二烷基硫酸钠-聚丙烯酰胺凝胶电泳分析对BSF进行分子量分析。BSF活性从对应于16 kDa和17 kDa分子量的凝胶条带中洗脱出来。16 kDa组分不含IL-2活性，而17 kDa组分与IL-2重叠。由于重组IL-2在抗IgM或金黄色葡萄球菌考恩I株依赖的检测系统中能够表现出显著的BSF活性，因此不能排除IL-2本身就是一种BSF。然而，这些研究证明了存在一种不含IL-2活性的BSF。
