Creative Biolabs has established an advanced surface plasmon resonance (SPR) platform to determine the interaction between therapeutic antibodies (like IgGs) and fragment crystallizable γ receptors (FcγR) or neonatal Fc receptor (FcRn). Through our high-throughput system, clients could accelerate their research with the most comprehensive view of therapeutic antibodies antibody and with reducing project costs and timelines.
The Interaction Between Therapeutic Antibodies and FcγRs/FcRn
Different FcγR subclasses are known to be present on human effector cells: the high-afﬁnity FcγRI (CD64) and the low-afﬁnity receptors FcγRIIa (CD32a), FcγRIIb (CD32b), FcγRIIIa (CD16a), and FcγRIIIb (CD16b). Within these ﬁve subclasses, different polymorphic variants exist, and in some cases, they can inﬂuence binding of IgG to these receptors. Therapeutic antibodies are one of the largest classes of modern biopharmaceuticals. Interactions of IgGs with effector cells through FcγRs are often considered a mode of action of therapeutic antibodies. FcγRs are cell surface receptors that can be found on innate immune effector cells such as natural killer cells and macrophages. A therapeutic IgG binds to a membrane-bound antigen on target cells by its complementary-determining regions (CDRs) in the variable domain, while the Fc region in the constant domain can bind to various FcγRs on effector cells, which could lead to effector function, like antibody-dependent cellular cytotoxicity (ADCC) or phagocytosis (ADCP). The binding kinetics and affinities of IgG-FcγR interactions are hence important parameters for understanding FcγR-mediated immune function. Furthermore, FcRn determines the half-life of IgGs in the bloodstream. Binding of Fc receptor to IgG takes place in the endosome at acidic pH, and the IgG is then recycled back into plasma at neutral pH, thereby preventing lysosomal degradation. Therefore, binding of therapeutic antibodies to FcγRs/FcRn should be evaluated as part of the critical quality attribute (CQA) assessment.
Determination of IgG-FcγRn/FcRn Interaction by SPR in Creative Biolabs
SPR is an extremely sensitive method to detect molecular interactions by tracking the change of signal via sensor chips. Aiming at rapid measurements of IgG samples for high-throughput screening purposes, scientists from Creative Biolabs have developed several SPR methods for FcγRn or FcRn binding to determine IgG-FcγRn/FcRn interaction. General binding response includes three phases: association phase, equilibrium phase, and dissociation phase. Monitoring the changes in the SPR signal over time results in a plot of the binding response versus time called sensorgram. Fitting of the sensorgram data allows calculation of binding parameters, such as the association (Ka) and dissociation (Kd) rate constants and ultimately determine the binding affinity (KD).
Creative Biolabs is pleased to share our cutting-edge technology and extensive expertise in the determination of IgG-FcγRn/FcRn interaction by SPR to facilitate our clients’ research and project development. We can offer high-quality customized SPR services by adjusting protocols to meet every unique requirement. Please feel free to contact us for more information.