Studies on the action of cell growth inhibiting factor partially purified from bovine colostrum.

据报道，牛初乳中含有高水平的促生长因子，可以刺激DNA合成和细胞分裂。据报告，在产后1天采集的母乳中含有最高水平的免疫反应IGF-I，此后水平迅速下降，在分娩后48小时内下降了80%。在本研究中，我们通过离子交换层析从部分纯化的牛初乳组分中发现了一种细胞生长抑制因子。在小鼠Lm成纤维细胞、大鼠L6成肌细胞和Balb/c 3T3细胞中测定了其活性。在低FCS条件下，该部位对L6和Balb/c 3T3细胞有明显的促增殖作用。用放射免疫法测定其IGF-I含量约为50 ng/ml，并研究了IGF-I对三种细胞生长的影响。令人惊讶的是，IGF-I抑制了LM细胞的增殖，而在低FCS条件下促进了L6和Balb/c 3T3细胞的生长。这些数据表明，该部位对LM细胞的抑制作用主要是通过IGF-I实现的。

It has been reported that bovine colostrum contains high levels of growth promoting factors that stimulate DNA synthesis and cell division. Human milk sampled at 1-day postpartum has also been reported to contain the highest level of immunoreactive IGF-I,levels falling rapidly thereafter, by 80% within 48-h after delivery. In this study, we found a cell-growth inhibiting factor in partially purified fraction from bovine colostrum with ion-exchange chromatography. The activity was measured in three cell lines, mouse LM fibroblast, rat L6 myoblast, and Balb/c 3T3 cells. The cell-growth inhibiting activity was observed only in LM cells, whereas the fraction stimulated cell proliferation in L6 and Balb/c 3T3 cells in low FCS condition. IGF-I concentration of the fraction was determined by RIA,and it contained about 50ng/ml of IGF-I.Then, effects of IGF-I on cell growth of these three cell lines were studied. To our surprise, IGF-I inhibited proliferation of LM cells, while it stimulated cell growth of L6 and Balb/c 3T3 cells in low FCS condition. These data suggest that the inhibitory action of the fraction to LM cells is mainly due to IGF-I.