重组人LFA3-Ig融和蛋白体内外生物活性研究

LFA3-Ig融合蛋白是由人淋巴细胞功能相关抗原3(LFA-3)与CD2结合的部分与人IgG1的Fc段构成的融合蛋白,采用基因工程技术大量制备,可用于治疗银屑病等自身免疫性疾病。实验利用体外细胞模型及正常食蟹猴作为体内模型,研究了上海市抗体工程技术研究中心研制和中试生产LFA3-Ig的生物学效应。结果表明:rhLFA3-Ig可通过特异性地结合淋巴细胞表面的CD2,抑制T淋巴细胞的活化,其体外活性与国外同类产品相比无显著差异;食蟹猴重复应用rhLFA3-Ig后,高剂量组外周血淋巴细胞有显著下降,于给药后48 h即降至最低,为给药前的76.1%;给药期间高剂量组外周血淋巴细胞波动于给药前的80%左右,至恢复期末,淋巴细胞恢复至给药前的90%左右。给药后,各剂量组CD2+、CD3+、CD4+及CD8+淋巴细胞计数均有不同程度的下降,且具有剂量相关性,停药后可恢复。上述结果为该重组融合蛋白提供了必要的临床前药效学资料,可作为其临床试验的重要参考。

Bioassay of the recombinant human lymphocyte function-associated antigen 3-IgG fusion protein in vitro and in vivo

The recombinant human lymphocyte function-associated antigen 3(LFA-3)-IgG fusion protein of fully dimeric protein was produced in large scale by recombinant DNA technology through linkage of LFA-3 with Fc fragment of IgG1,and this preparation had been tried in clinics for the treatment of adult patients with moderate or severe cases of chronic plaque psoriasis.In the present experiment,the efficiency of the recombinant human LFA3-Ig fusion protein(rhLAF3-IgG) prepared by Shanghai Antibody Engineering Research Center was assayed by the in vitro cell models and the in vivo cynomolgus monkey model,and compared with that of the marketed product of Amevive in USA.It was demonstrated by the in vitro cell models that the rhLFA3-Ig could interfere the activation of T lymphpcyte through the specific binding with CD2 on the surface of T lymphocytes,and its efficiency showed no significant difference with those of the foreign marketed products.Meanwhile,as demonstrated by the in vivo cynomolgus monkey model,repeated administration of rhLFA3-Ig induced a dose-dependent decrease in numbers of the total circulating lymphocytes,in which the maximal deletion of lymphocytes with high dosage was observed at 48 hour after administration of the product with 76.1% of the baseline.In addition,reduction of cell counts on CD2~ ,CD3~ ,CD4~ and CD8~ T lymphocytes was also observed in high dosage within 2 months after administration,accounting to 45.6%,44.5%,37.2% and 58.2% of baseline respectively,However,these counts in the lymphocyte numbers recovered up to 85.0%,71.9%,57.2% and 131.5% respectively over the entire recovery period of 6 months.These results can provide the essential preclinical pharmacodynamic data for the use of recombinant human LFA3-Ig fusion protein and for the useful references in clinical trials.