抗前列腺特异抗原/抗CD3双特异性单链抗体四聚体的活性研究

Biological activity of tetramer of bispecific single-chain antibody against human prostate-specific antigen and CD3 molecule

目的:研究抗前列腺特异抗原(PSA)/抗CD3双特异性单链抗体四聚体的生物活性.方法:利用流式细胞仪和51Cr释放试验评价双特异性单链抗体四聚体的抗原亲和活性和体外介导杀伤靶细胞的效果.利用裸鼠前列腺癌模型分析其在体内介导细胞毒T淋巴细胞对肿瘤细胞杀伤的能力.结果:抗PSA/抗CD3双特异性单链抗体四聚体可以特异性结合表达前列腺癌细胞和CD3阳性的淋巴瘤细胞,阳性结合率分别为70.4%和81%.在体外,有细胞毒T淋巴细胞存在时该四聚体可引起前列腺癌细胞的裂解,在抗体浓度固定组和效应细胞/靶细胞比例固定组,靶细胞裂解率分别随着效应细胞/靶细胞比例和抗体浓度的增加而增加,最高裂解率分别可以达到(80.3±5.2)%和(78.6±5.5)%.与对照组比较,接种前列腺癌细胞的裸鼠在体内注射激活的细胞毒T淋巴细胞的同时接受该四聚体的治疗后,肿瘤生长明显受到抑制(P<0.0001).结论:抗PSA/抗CD3双特异性单链抗体四聚体具有良好的生物学活性,具有体外杀伤肿瘤细胞和体内抑制肿瘤生长的作用.

AIM： To study the biological activity of tetramer of bispecific single-chain antibody against human prostate-specific antigen （PSA） and CD3 molecule. METHODS： Flow cytometry （FCM） was used to detect the binding activity of bispecific single-chain antibody to CD3-positive 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 51^Cr-release test. For in vivo evaluation of the antibody＇s 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 single-chain 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 51^Cr-release 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 ± 5.2 ） % and （78.6 ±5.5 ）% 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 single-chain antibody against human prostate-specific antigen and CD3 molecule has a good biological activity in bindingantigens, mediating lysis of LNCaP cells and inhibiting tumor growth.