^(99)Tc^m标记肝癌单抗片段HAb18 F(ab')_2方法改进及放免显像实验研究

^(99)Tc^m labeling of anti hepatoma monoclonal antibody fragment HAb18 F(ab′) _ 2 for hepatoma radioimmunoimaging by a modified direct method

目的 改进９９Ｔｃｍ 直接标记抗人肝癌单克隆抗体片段ＨＡｂ１８ Ｆ（ａｂ′）２ 的方法，进行９９ＴｃｍＨＡｂ１８ Ｆ（ａｂ′）２ 在荷人肝癌裸鼠模型中的放射免疫显像。方法 用ＳｎＣｌ２·２Ｈ２Ｏ 为还原剂，葡庚糖酸钠（ＧＨ）作转换络合剂和稳定剂，直接法标记抗体片段。Ｅｌｌｍａｎ 法测巯基数。用纸层析法、ＳＤＳＰＡＧＥ及放射自显影法进行标记物的质控。荷瘤裸鼠尾静脉注入标记抗体７－４ ＭＢｑ 后，于不同时间显像；在最佳显像时间点研究生物学分布。结果 整个标记过程可在１－５ ｈ 内完成，最佳标记率为８４－２％ 。该方法条件温和，没有导致标记抗体分子的降解。标记物５ ｈ 内的解离率＜０－５％ 。荷瘤裸鼠注射标记抗体后，２４ ｈ 肿瘤放射性浓聚最明显，除双肾区有浓聚外，胃肠道和甲状腺未见放射性浓聚；在该时间点，瘤／血和瘤／ 肝比值分别为１１－７ ±２－４ 和４－６ ±０－３ 。结论 ９９ＴｃｍＨＡｂ１８ Ｆ（ａｂ′）２

Objective To establish a modified direct method for 99 Tc m labeling anti hepatoma McAb fragment HAb18 F(ab′) 2 The stability, biodistribution and imaging were assessed Methods HAb18 F(ab′) 2 was labeled with 99 Tc m by direct labeling approach using stannous/glucoheptonate (Sn/GH) as reducing agent Ellman's reagent was used to determine the number of thiols in reduced F(ab′) 2 Labeling efficiency and homogeneity were measured by paper chromatography, SDS PAGE and autoradiography The human hepatocellular carcinoma (HHCC) bearing nude mice were divided into groups, and γ camera imaging was performed at different time points on different groups, and tissue samples of each group were collected after scanning for the biodistribution study. Results The labeling procedure was finished within 1 5 h that is much quicker as compared with the “pretinning” method which spent at least 21 h In vitro studies demonstrated that the radiolabeled McAb fragment was homogeneous Imaging and biodistribution analysis showed a significant tumor uptake at 24 h post injection of 99 Tc m labeled HAb18 F(ab′) 2 At 24 h point, the ratios of tumor to tumor free tissue, blood and liver, were 11 7±2 4 and 4 6±0 3, respectively Conclusions 99 Tc m HAb18 F(ab′) 2 conjugate prepared by this direct method assumes an effective ability to detect hepatoma in nude mice model