Kristensen F, Joncourt F, de Weck A L
Scand J Immunol. 1981 Aug;14(2):121-30. doi: 10.1111/j.1365-3083.1981.tb00191.x.
Serum exerts several effects in lymphocyte cultures, one of them being manifested very early. The presence of fetal calf serum (FCS) results in a markedly higher thymidine uptake within a few minutes, as compared with serum-free cultures. On the other hand, the uptake of uridine and other purine bases seem to be little influences by serum. Experiments comparing the uptake of thymidine into the cytoplasm or into trichloroacetic acid-precipitable material suggested that the intracellular thymidine pool increases in size when FCS is added. Using a Lineweaver--Burk plot for thymidine and uridine uptake over a 4-h period, no changes in uridine uptake were observed in the presence of FCS; on the contrary, serum induced an increased Vmax for thymidine, whereas Km remained constant. Cytofluorographic quantitation of G0 and G1 cells indicated that cells disappear more rapidly from the G1 phase in the presence of FCS. The addition of hydroxyurea to the cultures prevented this disappearance. The results taken together strongly suggest that serum contains a factor promoting the shift of G1 cells into the S phase. When a 4-h culture period was used, all sera from different species tested at low concentrations appeared to contain this activity.
血清在淋巴细胞培养中发挥多种作用，其中一种作用很早就会显现出来。与无血清培养相比，胎牛血清（FCS）的存在会在几分钟内导致胸腺嘧啶核苷摄取量显著更高。另一方面，尿苷和其他嘌呤碱的摄取似乎受血清影响很小。比较胸腺嘧啶核苷进入细胞质或三氯乙酸可沉淀物质的摄取情况的实验表明，添加FCS时细胞内胸腺嘧啶核苷池的大小会增加。使用Lineweaver - Burk图绘制4小时内胸腺嘧啶核苷和尿苷的摄取情况，在有FCS存在时未观察到尿苷摄取的变化；相反，血清诱导胸腺嘧啶核苷的Vmax增加，而Km保持不变。对G0和G1期细胞的细胞荧光定量分析表明，在有FCS存在时，细胞从G1期消失得更快。向培养物中添加羟基脲可阻止这种消失。综合这些结果强烈表明，血清中含有一种促进G1期细胞向S期转变的因子。当采用4小时培养期时，所有以低浓度测试的不同物种的血清似乎都含有这种活性。
