STUDY OF B CELL GROWTH BY EPSTEIN BARR VIRUS

EB病毒(EBV)感染人B细胞并诱导其表达 永垂不朽。EB病毒永生的分子基础主要是 未知。最近，人们观察到，当EBV永生化细胞 在极低密度下无血清培养，增殖停止 然后细胞就会死亡。然而，将无细胞上清液从 呈指数增长的EBV永生化细胞系可以拯救这些细胞 避免死亡并促进它们的扩散。最近，我们已经确定了 IL-6作为EB病毒永生化B细胞的自分泌生长因子 细胞(Tosato，G.等人，J.Virol，1990)，然而，只有大约25% 自分泌生长因子的活性可归因于IL-6，而 剩余的自分泌生长因子活性驻留在低分子 重量分量。 我们试图鉴定这种低分子量的活性。这个 纯化是通过凝胶过滤连续完成的。 层析、交换层析、吸附和凝胶渗透 层析、反相高效液相色谱法和亲水相互作用高效液相色谱法。这个 用这种方法提纯的物质进行了质谱分析。二 主要成分为乳酸和草酸。 人工合成的LA在1-10 mm时刺激EB病毒永生化的B细胞生长， 在EB病毒培养上清液中达到的LA浓度 永生的细胞系。仅这种分子就被发现解释了所有 上清液中低分子量自分泌生长因子的活性 EB病毒永生化的B细胞。因此，LA是一种自分泌刺激分子 诱导EB病毒永生化的B细胞增殖。

Epstein-Barr virus (EBV) infects human B cells and induces their immortalization. The molecular basis for EBV immortalization is largely unknown. Recently, it was observed that when EBV immortalized cells are cultured without serum at critically low densities, proliferation ceases and the cells die. However, addition of cell-free supernatants from exponentially growing EBV-immortalized cell lines can rescue these cells from death and promote their proliferation. Recently, we have identified IL-6 as being one of the autocrine growth factors for EBV-immortalized B cells (Tosato, G. et al, J. Virol., 1990) However, only approximately 25% of autocrine growth factor activity is attributable to IL-6 while the remaining autocrine growth factor activity resides in a low molecular weight component. We sought to identify this low molecular weight activity. The purification was accomplished, sequentially, by gel filtration chromatography, exchange chromatography, adsorption and gel permeation chromatography, reverse phase HPLC and hydrophilic-interaction HPLC. The material purified in this manner was analyzed by mass spectrometry. Two major components were identified as lactic acid (LA) and oxalic acid. Synthetic LA stimulated growth in EBV-immortalized B cells at 1 to 10 mM, a concentration of LA achieved in the culture supernatant of EBV- immortalized cell lines. This molecule alone was found to account for all the low molecular weight autocrine growth factor activity in supernatants of EBV-immortalized B cells. Thus, LA is an autocrine stimulatory molecule that induces the proliferation of EBV-immortalized B cells.