Conversion of vitamin D3 binding protein (group-specific component) to a macrophage activating factor by the stepwise action of beta-galactosidase of B cells and sialidase of T cells.
Conversion of vitamin D3 binding protein (group-specific component) to a macrophage activating factor by the stepwise action of beta-galactosidase of B cells and sialidase of T cells.
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DOI：
10.4049/jimmunol.151.5.2794
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发表时间：
1993-09
影响因子：
4.4
通讯作者：
Nobuto Yamamoto;R. Kumashiro
中科院分区：
文献类型：
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作者：
Nobuto Yamamoto;R. Kumashiro
血清α 2-球蛋白组分中高度保守的DBP（人DBP称为Gc）可以通过用B细胞的β-半乳糖苷酶和T细胞的唾液酸酶逐步修饰Gc糖蛋白而转化为有效的巨噬细胞活化因子。这些糖苷酶，β-半乳糖苷酶和唾液酸酶，是膜结合的，不溶于培养基。因此，Gc蛋白与B细胞和T细胞的连续接触，可能是通过特异性受体，是Gc糖蛋白转化为巨噬细胞活化因子所必需的。T细胞唾液酸酶在巨噬细胞活化中的重要作用通过SM/J小鼠的腹膜非贴壁细胞（其T细胞缺乏唾液酸酶活性）不能将Gc蛋白转化为巨噬细胞活化因子并且因此不能活化巨噬细胞的发现得到证实。用唾液酸酶处理脂质代谢物处理的SM/J小鼠非贴壁细胞的条件培养基有效地产生巨噬细胞活化因子。当首先用可溶性或固定化唾液酸酶处理Gc蛋白，并将其用于脂质代谢物处理的SM/J小鼠非贴壁细胞或BALB/c小鼠B细胞的培养基中培养2小时时，得到的条件培养基含有大量的巨噬细胞活化因子。这些结果支持Gc蛋白携带具有半乳糖和唾液酸末端的二分支三糖的假设。
Highly conserved DBP (human DBP is known as Gc) of serum alpha 2-globulin fraction can be converted to a potent macrophage activating factor by stepwise modification of Gc glycoprotein with beta-galactosidase of B cells and sialidase of T cells. These glycosidases, beta-galactosidase and sialidase, are membrane bound and not soluble in culture medium. Thus, consecutive contact of Gc protein with B cells and T cells, presumably via specific receptors, is required for conversion of Gc glycoprotein to the macrophage activating factor. The essential role of T cell sialidase in macrophage activation was confirmed by the finding that peritoneal nonadherent cells of SM/J mouse, whose T cells are deficient in sialidase activity, were unable to convert Gc protein to the macrophage activating factor and thus did not activate macrophages. Treatment with sialidase of a conditioned medium of lipid metabolite-treated SM/J mouse nonadherent cells efficiently generated the macrophage activating factor. When Gc protein was first treated with soluble or immobilized sialidase and used in a medium for 2 h cultivation of lipid metabolite-treated SM/J mouse nonadherent cells or BALB/c mouse B cells, the resultant conditioned media contained a large amount of the macrophage activating factor. These results support the hypothesis that Gc protein carries a dibranched trisaccharide with galactose and sialic acid termini.