Monoclonal antibody (mAb), one arm of the immunotherapy, has been used with considerable success in the past years for human disease treatment, especially cancers. All of the currently approved antibodies belong to the IgG class, which are proven to be effective but still have limitations at the same time. Efforts have been made by scientists to explore antibodies of alternative immunoglobulin classes, such as immunoglobulin E (IgE), to improve the therapeutic outcome. Creative Biolabs has been concentrated on the therapeutic antibody development field for years, including both IgG and non-IgG isotypes. Especially, we offer IgE antibody development and glycoengineering services.
Introduction to IgE Antibody
IgE antibody is the least abundant Ig in human serum (<1 μg/ml). It exists in both a soluble form and a membrane-bound receptor. Structurally, IgE consists of two heavy (ε type) and two light chains, with the variable regions of both chains together forming the antigen-binding site. Functionally, IgE is known for its involvement in both anti-parasitic and allergic immune reactions. One important characteristic of IgE antibodies is that they can bind to Fc receptors (FcεRI and FcεRII) expressed on immune cells (e.g., macrophages, monocytes, and basophils), thereby recruiting and activating them as effector cells to generate antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP), two main mechanisms by which antibodies can eliminate tumor cells. IgE can bind very tightly to its high-affinity receptor (FcεRI), even in the absence of antigen, which makes IgE valuable therapeutic agents in cancer treatment, as compared to IgG antibodies.
IgE Glycosylation
IgE is a heavily glycosylated glycoprotein, whose glycans make up more than 10% of its molecular mass. There are seven glycosylation sites on each heavy chain of IgE, i.e. asparagine (Asn)-140, Asn-168, Asn-218, Asn-265, Asn-371, Asn-383, and Asn-394. Glycosylation sites 1-5 are occupied by complex type N-glycans, which are primarily fully galactosylated biantennary structures, containing a core fucose and one or two sialic acids. However, Asn-394 is occupied exclusively by oligomannose structures, predominantly Man5GlcNAc2. This glycosylation site is homologous to the Fc glycosylation site in IgG.
Fig.1 The structure and glycosylation status of human serum IgE. (Montero-Morales, 2017)
The Impact of Glycosylation on IgE Functions
Studies have reported that the number and nature of IgE glycans significantly affect the biological and pharmacological activity of IgE-based antibodies. Firstly, glycosylation at the Asn-394 has been shown to be essential for the binding of IgE to the high-affinity receptor FcεRI and initiation of anaphylaxis. Secondly, glycosylation of IgE has been shown to shield IgE from interacting with FcεRII, the low-affinity IgE receptor. Thirdly, galectins have been shown to interact with IgE in a glycosylation-dependent manner. Based on these findings, it can be inferred that manipulating the glycan structure of IgE offers a unique opportunity to improve the clinical performance of IgE-based antibodies.
IgE Glyco-engineering Services Provided by Creative Biolabs
With the aim of improving current cancer treatment status, Creative Biolabs has focused on the discovery and development of this innovative immunotherapy agent for years. Based on our combined technologies and know-how, we can rationally design custom-specific strategies for your IgE glycoengineering projects using a broad range of techniques, including chemical synthesis, cell culturing, glycoanalysis, etc.
For more detailed information, please feel free to contact us or directly send us an inquiry.
Reference
- Montero-Morales, L.; et al. Recombinant plant-derived human IgE glycoproteomics. Journal of Proteomics. 2017, 161: 81-87.
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