Department of Antibody Discovery and Protein Engineering, MedImmune LLC, Gaithersburg, Maryland, United States of America.
Department of Respiratory, Inflammation, and Autoimmunity, MedImmune LLC, Gaithersburg, Maryland, United States of America.
PLoS One. 2019 Jan 25;14(1):e0211236. doi: 10.1371/journal.pone.0211236. eCollection 2019.
Interleukin-21 (IL-21), a member of the common cytokine receptor γ chain (γc) family, is secreted by CD4+ T cells and natural killer T cells and induces effector function through interactions with the IL-21 receptor (IL-21R)/γc complex expressed on both immune and non-immune cells. Numerous studies suggest that IL-21 plays a significant role in autoimmune disorders. Therapeutic intervention to disrupt the IL-21/IL-21R/γc interaction and inhibit subsequent downstream signal transduction could offer a treatment paradigm for these diseases. Potent neutralizing antibodies reported in the literature were generated after extensive immunizations with human IL-21 alone and in combination with various adjuvants. To circumvent the laborious method of antibody generation while targeting a conserved functional epitope, we designed a novel alternating-antigen immunization strategy utilizing both human and cynomolgus monkey (cyno) IL-21. Despite the high degree of homology between human and cyno IL-21, our alternating-immunization strategy elicited higher antibody titers and more potent neutralizing hybridomas in mice than did the immunization with human IL-21 antigen alone. The lead hybridoma clone was humanized by grafting the murine complementarity-determining regions onto human germline framework templates, using a unique rational design. The final humanized and engineered antibody, MEDI7169, encodes only one murine residue at the variable heavy/light-chain interface, retains the sub-picomolar affinity for IL-21, specifically inhibits IL-21/IL-21R-mediated signaling events and is currently under clinical development as a potential therapeutic agent for autoimmune diseases. This study provides experimental evidence of the immune system's potential to recognize and respond to shared epitopes of antigens from distinct species, and presents a generally applicable, novel method for the rapid generation of exceptional therapeutic antibodies using the hybridoma platform.
白细胞介素 21（IL-21）是共同细胞因子受体γ链（γc）家族的成员，由 CD4+T 细胞和自然杀伤 T 细胞分泌，并通过与表达在免疫和非免疫细胞上的 IL-21 受体（IL-21R）/γc 复合物相互作用来诱导效应功能。许多研究表明，IL-21 在自身免疫性疾病中发挥重要作用。阻断 IL-21/IL-21R/γc 相互作用并抑制随后的下游信号转导的治疗干预可能为这些疾病提供一种治疗模式。文献中报道的强效中和抗体是在用人 IL-21 单独和与各种佐剂联合进行广泛免疫接种后产生的。为了避免在针对保守功能表位时生成抗体的繁琐方法，我们设计了一种利用人和食蟹猴（cyno）IL-21 的新型交替抗原免疫策略。尽管人 IL-21 和 cyno IL-21 之间具有高度同源性，但与单独用人类 IL-21 免疫相比，我们的交替免疫策略在小鼠中引起了更高的抗体滴度和更有效的中和杂交瘤。领先的杂交瘤克隆通过将鼠互补决定区移植到人类种系框架模板上进行人源化，使用独特的合理设计。最终的人源化和工程抗体 MEDI7169 在可变重链/轻链界面处仅编码一个鼠残基，保留对 IL-21 的亚皮摩尔亲和力，特异性抑制 IL-21/IL-21R 介导的信号事件，目前正在临床开发中作为自身免疫性疾病的潜在治疗剂。这项研究提供了实验证据，证明免疫系统有可能识别和响应来自不同物种的抗原的共享表位，并提出了一种普遍适用的、新颖的方法，可利用杂交瘤平台快速生成卓越的治疗性抗体。
