抗胃癌单克隆抗体MG7的内化超微形态学研究

Ultrastructural Studies of Endocytosis of an Antigastric Cancer Monoclonal Antibody MG7

应用胶体金技术,对抗人胃癌单克隆抗体MG7在KATOⅢ人胃癌细胞系中的内化途径、过程进行了超微形态学观察。4℃时MG7与靶细胞只有结合但无内化。在37℃条件下,见细胞表面结合的MG7主要以下述几种方式进入细胞内:(1)吸附微胞饮;(2)被覆小凹;(3)吸附大胞饮;(4)吸附吞噬;(5)直接穿膜。入胞后MG7通过管泡结构送入多泡小体及溶酶体。本研究结果表明,MG7是一具有强内化能力的抗体,可作为免疫导向诊治的载体;另一方面则表明,MG7内化后几乎均被溶酶体降解。提示,如能采取某种人为因素干预MG7的细胞内分布过程,将有可能提高MG7的导向诊治效率。

Ultrastructural examination was carried out of the pathway and process of endocytosis of an antigastric cancer monoclonal antibody MG7 in human gastric cancer cell line MG7 by colloidal gold technique. At 4℃MG7 was bound to the target cell; however, no endocytosis occurred. When heated to 37℃, the target cell was found to endocytose MG7 in the following patterns. (1) adsorptive micropinocytosis; (2) coated pit; (3) adsorptive macropinocytosis, (4) adsorptive phagocytosis, (5) direct penetration. After entry MG7 was delivered sequentially via tubulovesicular structures to mu-Itivesicular bodies and then to lysosomes. These findings show that MG7 is a highly internalizing antibody and may be used as a carrier for immunotargeting. Moreover, the results indicate that MG7 was almost entirely broken down in the lysosome following its endocytosis, suggesting that, if the intracellular distribution process of MG7 can be altered by employing some intervening measures, the efficiency of targeting diagnosis and therapy using MG7 may be reasonably improved.