Chief Scientific Officer Conigen Bioscience, Inc. Worcester, Massachusetts, United States
Disclosure(s):
Shixia Wang, PhD: No relevant disclosure to display
Introduction/Rationale: Type I interferons play a crucial role in regulating immune responses through the IFNα/β receptor (IFNαR). IFNαR is a heterodimer complex composed of IFNαR1 and IFNαR2 subunits on the cell surface. Binding of the ectodomains (ECDs) of the dimeric receptor is critical for the cytokine to initiate signaling cascade. To mimic the dimeric receptor conformation, we engineered a novel cis-heterodimer IFNαR1/R2 protein for human IFNαR using the ECDs of IFNαR1 and IFNαR2.
Methods: IFNαR1 and IFNαR2 ECDs were fused with a heterodimer motif at the C-terminus of each chain. The recombinant IFNαR1/R2 heterodimer protein was expressed/purified from HEK293 cells. The IFNαR1/R2 protein bioactivities were evaluated for binding of specific antibodies and Type I interferon by ELISA and surface plasmon resonance (SPR). To evaluate the immunogenicity, mice were immunized with IFNαR1/R2 protein. The IFNαR1/R2-specific antibody responses in mice were measured by ELISA. IFNαR1/R2-specific monoclonal antibodies (mAbs) were generated by hybridoma technology.
Results: The IFNαR1/R2 heterodimer protein could potently bind to the IFNαR1 and IFNαR2 specific antibodies and Type I interferon as measured by ELISA and SPR. Notably, the dimeric form of IFNαR1/R2 dramatically enhanced the binding to the interferon by >50 fold as indicated by EC50 and KD values, compared to the monomeric receptor proteins. Mouse immunogenicity study demonstrated that the IFNαR1/R2 heterodimer protein induced high titers of antibody responses against both IFNαR1 and IFNαR2 subunits. The mAbs generated from immune mouse B cells exhibited diverse IgG profiles and binding specificities against both IFNαR1 and IFNαR2 subunits and heterodimer alone.
Conclusion: The engineered IFNαR1/R2 heterodimer mimics the IFNα/β receptor native conformation with better bioactivities and can generate diverse antibodies by immunization. This innovative IFNαR1/R2 heterodimer protein is a valuable new molecule for basic immunology research and drug discovery.
