Li Q G, Congote L F
Endocrine Laboratory, Royal Victoria Hospital, Montreal, Canada.
Ann N Y Acad Sci. 1991;628:241-9. doi: 10.1111/j.1749-6632.1991.tb17251.x.
During the isolation and purification of erythroid cell-stimulating factors from fetal tissues and blood, we found that they were almost invariably contaminated with substances that inhibited thymidine incorporation into erythroid cells of fetal bovine liver. We have isolated and partially sequenced three of these inhibitory factors. The first one was a 46-kDa heparin-binding protein from fetal bovine serum with 80% sequence identity with human apolipoprotein H (apo H). Although human apo H had no inhibitory activity on thymidine incorporation, the bovine apo H-like protein inhibited thymidine incorporation with an ID50 of 36 nM. It probably belongs to a group of heparin-binding apolipoproteins such as apo B and E, which have been reported to inhibit hematopoietic cells. The second inhibitor isolated from fetal bovine serum was clearly cytotoxic at a concentration of 1 nM. This 11-kDa peptide seems to be structurally related to the anaphylatoxins. The third inhibitor was isolated from human fetal intestine. The amino-terminal sequence of this protein was nearly identical to the amino-terminal sequence of human phospholipase A2 isolated from pancreas or lung. Bovine liver erythroid cell membranes are particularly sensitive to phospholipases. Since the synthesis and secretion of phospholipase A2 has been reported to be under the control of interleukin-1 or tumor necrosis factor in different cells, it is possible that this enzyme may be secreted locally and play an important role in tissue remodeling during injury or fetal development.
在从胎儿组织和血液中分离纯化红细胞生成刺激因子的过程中，我们发现它们几乎总是被抑制胸苷掺入胎牛肝脏红细胞的物质所污染。我们已经分离并部分测序了其中三种抑制因子。第一种是来自胎牛血清的46 kDa肝素结合蛋白，与人载脂蛋白H（apo H）有80%的序列同一性。虽然人apo H对胸苷掺入没有抑制活性，但牛apo H样蛋白以36 nM的半数抑制浓度（ID50）抑制胸苷掺入。它可能属于一组肝素结合载脂蛋白，如apo B和E，据报道它们会抑制造血细胞。从胎牛血清中分离出的第二种抑制剂在浓度为1 nM时具有明显的细胞毒性。这种11 kDa的肽在结构上似乎与过敏毒素有关。第三种抑制剂是从人胎儿肠道中分离出来的。这种蛋白质的氨基末端序列与从胰腺或肺中分离出的人磷脂酶A2的氨基末端序列几乎相同。牛肝红细胞膜对磷脂酶特别敏感。由于据报道磷脂酶A2的合成和分泌在不同细胞中受白细胞介素-1或肿瘤坏死因子的控制，因此这种酶可能在局部分泌，并在损伤或胎儿发育过程中的组织重塑中发挥重要作用。
