Biological activity of tetramer of bispecific singleª²chain antibody against human prostateª²specific antigen and CD3 molecule

    WANG Dong, CHEN Jinª²Hua, WU Guoª²Jun, WANG He, WU Weiª²Zhen, YANG Shunª²Liang, LIN Wenª²Hong, TAN Jianª²Ming

    Department of Urology, Statistic Room, Fuzhou General Hospital, Nanjing Military Area Commond, Fuzhou 350025, China, Department of Urology, Xijing Hospital, Fourth Military Medical University, Xi¬ðan 710033, China

    ¡¾Abstract¡¿ AIM: To study the biological activity of tetramer of bispecific singleª²chain antibody against human prostateª²specific antigen (PSA) and CD3 molecule. METHODS: Flow cytometry (FCM) was used to detect the binding activity of bispecific singleª²chain antibody to CD3ª²positive cell line Jurkat and prostate carcinoma cell line LNCaP. The efficacy of the antibodiy in mediating tumor cell lysis in vitro was determined by using the 51Crª²release test. For in vivo evaluation of the antibody¬ðs activity, a nude mouse model was used. The mice were inoculated with LNCaP prostate cancer cells. RESULTS: It was demonstrated that the tetramer of bispecific singleª²chain antibody could bind to the Jurkat and LNCaP cells with high specificity. The percents of the cells bond by the antibody were 70.4% and 81%, respectively. In vitro, with activated CTLs as effector cells, a specific lysis of LNCaP cells mediated by the antibody was confirmed by 51Crª²release assay. The specific lysis rate of LNCaP cells was positively correlated to tBsAb concentration or effector / target cell ratio. The highest specific lysis rates were (80.3¡À5.2)% and (78.6¡À5.5)% in fixed antibody concentration group and fixed effector/target cell ratio group, respectively. In vivo, the antibody could suppress the tumor growth in nude mice significantly as compared to the group treated only with CTLs and the untreated control group (P<0.0001). CONCLUSION: The tetramer of bispecific singleª²chain antibody against human prostateª²specific antigen and CD3 molecule has a good biological activity in binding antigens, mediating lysis of LNCaP cells and inhibiting tumor growth. ......