Tokyo University of Science, Yamazaki 2641, Noda, Chiba 278-8510, Japan.
J Biosci Bioeng. 2011 Apr;111(4):391-6. doi: 10.1016/j.jbiosc.2010.12.007. Epub 2011 Jan 6.
We previously reported that chimeric monoclonal antibodies (mAbs) with tandemly repeated Fc domains, which were developed by introducing tandem repeats of Fc domains downstream of 2 Fab domains, augmented binding avidities for all Fcγ receptors, resulting in enhanced antibody (Ab)-dependent cellular cytotoxicity. Here we investigated regarding Ab-dependent cellular phagocytosis (ADCP) mediated by these chimeric mAbs, which is considered one of the most important mechanisms that kills tumor cells, using two-color flow cytometric methods. ADCP mediated by T3-Ab, a chimeric mAb with 3 tandemly repeated Fc domains, was 5 times more potent than that by native anti-CD20 M-Ab (M-Ab hereafter). Furthermore, T3-Ab-mediated ADCP was resistant to competitive inhibition by intravenous Ig (IVIG), although M-Ab-mediated ADCP decreased in the presence of IVIG. An Fcγ receptor-blocking study demonstrated that T3-Ab mediated ADCP via both FcγRIA and FcγRIIA, whereas M-Ab mediated ADCP exclusively via FcγRIA. These results suggest that chimeric mAbs with tandemly repeated Fc domains enhance ADCP as well as ADCC, and that Fc multimerization may significantly enhance the efficacy of therapeutic Abs.
我们之前曾报道，通过在 2 个 Fab 结构域下游引入 Fc 结构域串联重复，开发出的具有串联重复 Fc 结构域的嵌合单克隆抗体（mAb），增强了对所有 Fcγ 受体的结合亲和力，从而增强了抗体（Ab）依赖的细胞毒性。在这里，我们使用双色流式细胞术方法研究了这些嵌合 mAb 介导的 Ab 依赖的细胞吞噬作用（ADCP），这被认为是杀死肿瘤细胞的最重要机制之一。由 T3-Ab 介导的 ADCP，其是一种具有 3 个串联重复 Fc 结构域的嵌合 mAb，比天然抗 CD20 M-Ab（以下简称 M-Ab）强 5 倍。此外，T3-Ab 介导的 ADCP 对静脉注射免疫球蛋白（IVIG）的竞争抑制具有抗性，尽管 M-Ab 介导的 ADCP 在 IVIG 存在下减少。Fcγ 受体阻断研究表明，T3-Ab 通过 FcγRIA 和 FcγRIIA 介导 ADCP，而 M-Ab 仅通过 FcγRIA 介导 ADCP。这些结果表明，具有串联重复 Fc 结构域的嵌合 mAb 增强了 ADCP 和 ADCC，并且 Fc 多聚化可能显著增强治疗性 Ab 的疗效。
