Expressing, Purifying Anti-hepatoma Single-chain Fv25 And Its Radioimmunoimaging With ～(131)I Labeled

Primary liver tumor is one of the most serious diseases in China, which has 44% of allhepatoma cases in the world and the number is increasing every year, Hepatoma is difficultto diagnose in its early stages; and effective treatments are yet to be discovered. Earlydiagnosis is of the greatest importance at present Tumor radioimmunoimaging(RII) appliescertain isotopes, labeled with immno-antibody, to the corresponding tumor antigen in thebody?1: expression and purification of mscFv25In order to express mscFv25 in E.coli,vector pGEX 4T-mscFv25 was transformed into E.coli JM109, then induced by IPTG to express the aim proteino It was found that a new protein bond appeared with a molecular weight 52KD in 12.5% SDS-PAGE gel,the expressed GST- mscFv25 accouts for 12% of the total bacterial proteins by estimation of gel laser scanning.Because most of the expressed proteins were inclusion body.then we using the two-step Glutathione-sepharose 4B affinity chromatography method applied by Bulk GST Purification Modules(products of Pharmacia biotech),and purified the recombinantmscFv25.2: Radioimmunoimaging of hepatocellular carcinoma with 131I labeled anti-hepatoma single chain Fv25BALB/c mice bearing HHCC were divided into two groups, one group consisted of twenty animals and another group consisted of five animals as the negative teams.The tested animal received approximately 0.4ml mscFv25 with about 5.6MBq through a lateral tail vein or peritoneal way,and the negative team animals received approximately 0.4ml 1 A8Fv with about 5.6MBq through a lateral tail vein ,then imaged on a SPECT , data were collected 50000 counts per image and peak energy settings at the 364ke V (20%) window for 131I.At time 28h postinjection, two groups of mouse were killed , the blood and other organs of interested were collected. Tissues were washed, blotted, weighed and counted in a radioactivity calibrator.The result shows twenty nude mice bearing human hepatocellular carcinoma showed positive image,, The optimum time was 6~8h after injection, and the tumor/liver ratio is 9.63 ?.05?The introduction of scFv as targeting devices in nuclear medicine is well develo ped and many different antibodies which labeled with a variety of isotopes have been reported in cancer diagnosis. It seemed that I31I is the most popular radionuclide for nuclear medicine imaging because of its favorable physical characteristics, low cost, and ready availability. 1311 labeled scFv should be superior to other big molecule radioimmunoconjugates for use in tumor RII.In this study, we get the conclusion that 131I-mscFv25 can elevate the T/NT ratio,shorting imaging interval, it is prospective in clinical application...