卵巢癌COC166-9单克隆抗体片段的制备及其在放射免疫显像中的应用

Preparation of F(ab′) 2 Fragment of Monoclonal Antibody COC166 9 and Its Experimental Study of Radioimmunoimmaging for Ovarian Carcinoma

目的：制备抗卵巢上皮性癌ＣＯＣ１６６－９单克隆抗体片段Ｆ（ａｂ′）２，并进行放射免疫（放免）显像。方法：采用无花果酶消化ＣＯＣ１６６－９单克隆抗体，其酶切产物经ＳＤＳ－ＰＡＧＥ电泳鉴定及ＤＥＡＥ－３２离子交换柱纯化获得Ｆ（ａｂ′）２片段。采用１３１Ｉ标记的Ｆ（ａｂ′）２（片段组）、ＣＯＣ１６６－９（全抗体组）和正常鼠ＩｇＧ（对照组），分别进行荷人卵巢癌裸鼠移植瘤放免显像，并对其放免结果进行比较。结果：（１）片段Ｆ（ａｂ′）２的产率为５４％，为最大理论产率的８０％。酶联免疫吸附和免疫细胞化学染色实验均证实其保留较好的免疫活性。（２）７２小时显像可见Ｆ（ａｂ′）２片段组移植瘤部位有高的放射性物质浓集，图像清晰，胸、腹腔高本底区几乎无放射性物质分布，肿瘤与非肿瘤放射性活度的比值（Ｔ／ＮＴ）高于全抗体组和对照组。结论：利用无花果酶可获得免疫活性好、产率高的单克隆抗体片段。应用其进行放免显像，图像清晰度优于全抗体。

Objectives: To obtain F(ab′) 2 fragment of monoclonal antibody (McAb) COC166 9 and to perform its radioimmunoimaging (RII) for ovarian carcinoma. Methods: McAb COC166 9 was digested into F(ab′) 2 by ficin and tested by SDS PAGE. After purification by DEAE 32, F(ab′) 2, COC166 9 and normal murine IgG (nMIgG) were labelled by 131 I and injected intraperitoneally into three groups of nude mice bearing human ovarian cancer xenografts respectively 72 hours after injection, RII was performed in three groups of mice. Results: The yield of F(ab′) 2 was 54%, about 80% of the maximal theoretical yield. Good immunoreactivity of F(ab′) 2 retained with higher ratio of tumor to normal tissue radioactivity (T/NT) than that of intact COC166 9. RII showed better result with lower nonspecific background than the latter. Conclusion: F(ab′) 2 could be obtained by ficin digestion with good yield and immunoactivity as well as better RII than intact monoclonal antibody.