Kuwabara I, Tagawa M, Harada Y, Ito T, Taniguchi M
Division of Molecular Immunology, School of Medicine, Chiba University.
Jpn J Cancer Res. 1989 Oct;80(10):981-7. doi: 10.1111/j.1349-7006.1989.tb01637.x.
We analyzed the biochemical properties and biological significance of the melanoma antigen secreted in the culture supernatants of B16 melanoma cells. The 80 kilodalton (kd) molecule bearing the epitopes of mouse melanoma antigen was found to associate noncovalently with an 18 kd moiety in the culture supernatants as well as on the cell surface. Tunicamycin treatment of B16 cells did not affect the expression of the 69 kd nonglycosylated form of the 80 kd molecule but did abolish the association between the two molecules on the cell surface. We could not detect this antigen as a soluble form when the N-linked glycosylation was inhibited. Therefore, the glycosylation of the 80 kd molecule is essential for the formation of the 80 kd/18 kd complex and also for the secretion. Moreover, the affinity-purified melanoma antigen from the supernatants could induce anti-melanoma suppressor cells which block the generation of cytotoxic T lymphocytes against melanoma cells. Thus, the 80 kd glycoprotein as a soluble melanoma antigen performed a pivotal function in the escape mechanisms of melanoma cells from the host immune surveillance system.
我们分析了B16黑色素瘤细胞培养上清液中分泌的黑色素瘤抗原的生化特性和生物学意义。发现带有小鼠黑色素瘤抗原表位的80千道尔顿（kd）分子在培养上清液以及细胞表面与一个18 kd的部分非共价结合。用衣霉素处理B16细胞不影响80 kd分子的69 kd非糖基化形式的表达，但确实消除了细胞表面这两种分子之间的结合。当N-连接糖基化被抑制时，我们无法检测到这种抗原的可溶性形式。因此，80 kd分子的糖基化对于80 kd/18 kd复合物的形成以及分泌都是必不可少的。此外，从上清液中亲和纯化的黑色素瘤抗原可诱导抗黑色素瘤抑制细胞，这些细胞可阻断针对黑色素瘤细胞的细胞毒性T淋巴细胞的产生。因此，80 kd糖蛋白作为一种可溶性黑色素瘤抗原，在黑色素瘤细胞逃避宿主免疫监视系统的机制中发挥了关键作用。
