Yamamoto N, Homma S
Department of Biochemistry, Temple University School of Medicine, Philadelphia, PA 19140.
Proc Natl Acad Sci U S A. 1991 Oct 1;88(19):8539-43. doi: 10.1073/pnas.88.19.8539.
A brief (30 min) treatment of mouse peritoneal cells (mixture of nonadherent lymphocytes and adherent macrophages) with 1-20 micrograms of lysophosphatidylcholine (lyso-PC) per ml in serum-supplemented RPMI medium 1640, followed by a 3-hr cultivation of the adherent cells alone, results in a greatly enhanced Fc receptor-mediated phagocytic activity of macrophages. This rapid process of macrophage activation was found to require a serum factor, the vitamin D3 binding protein (the human protein is known as group-specific component; Gc). Efficient activation of macrophages was achieved by using medium containing purified human Gc protein. Analysis of intercellular signal transmission among nonadherent (B and T) cells revealed that lyso-PC-treated B cells modify Gc protein to yield a proactivating factor, which can be converted by T cells to the macrophage-activating factor. This rapid generation process of the macrophage-activating factor was also demonstrated by stepwise incubation of Gc protein with lyso-PC-treated B-cell ghosts and untreated T-cell ghosts, suggesting that Gc protein is modified by preexisting membranous enzymes to yield the macrophage-activating factor. Incubation of Gc protein with a mixture of beta-galactosidase and sialidase efficiently generated the macrophage-activating factor. Stepwise incubation of Gc protein with B- or T-cell ghosts and sialidase or beta-galactosidase revealed that Gc protein is modified by beta-galactosidase of B cells and sialidase of T cells to yield the macrophage-activating factor. Administration to mice of a minute amount (4-10 pg per mouse) of in vitro, enzymatically generated macrophage-activating factor resulted in a greatly enhanced (3- to 7-fold) ingestion activity of macrophages.
在补充血清的RPMI 1640培养基中，用每毫升含1 - 20微克溶血磷脂酰胆碱（lyso - PC）的溶液对小鼠腹腔细胞（非贴壁淋巴细胞和贴壁巨噬细胞的混合物）进行短暂（30分钟）处理，然后仅对贴壁细胞进行3小时培养，结果巨噬细胞的Fc受体介导的吞噬活性大大增强。发现这种巨噬细胞激活的快速过程需要一种血清因子，即维生素D3结合蛋白（人类蛋白质称为组特异性成分；Gc）。通过使用含有纯化的人Gc蛋白的培养基可实现巨噬细胞的有效激活。对非贴壁（B细胞和T细胞）之间的细胞间信号传递分析表明，经lyso - PC处理的B细胞会修饰Gc蛋白以产生一种前激活因子，该因子可被T细胞转化为巨噬细胞激活因子。通过将Gc蛋白与经lyso - PC处理的B细胞幽灵和未处理的T细胞幽灵逐步孵育，也证明了巨噬细胞激活因子的这种快速生成过程，这表明Gc蛋白被预先存在的膜酶修饰以产生巨噬细胞激活因子。将Gc蛋白与β - 半乳糖苷酶和唾液酸酶的混合物孵育可有效产生巨噬细胞激活因子。将Gc蛋白与B细胞或T细胞幽灵以及唾液酸酶或β - 半乳糖苷酶逐步孵育表明，Gc蛋白被B细胞的β - 半乳糖苷酶和T细胞的唾液酸酶修饰以产生巨噬细胞激活因子。给小鼠注射微量（每只小鼠4 - 10皮克）体外酶促产生的巨噬细胞激活因子，可使巨噬细胞的摄取活性大大增强（3至7倍）。
