Open AccessDiscovery and characterization of potent IL-21 neutralizing antibodies via a novel alternating antigen immunization and humanization strategy
Author(s) -
Reena Varkey,
Qun Du,
Jodi L. Karnell,
Xiaodong Xiao,
Kerry A. Casey,
R. Jeremy Woods,
Kim Rosenthal,
Susan Wilson,
William F. Dall’Acqua,
Herren Wu,
Ronald Herbst,
Rachel Ettinger,
Melissa Damschroder
Publication year - 2019
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0211236
Subject(s) - antibody , epitope , immune system , biology , antigen , antibody dependent cell mediated cytotoxicity , immunology , monoclonal antibody
Interleukin-21 (IL-21), a member of the common cytokine receptor γ chain (γ c ) 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)/γ c 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/γ c 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.