Immunoglobulin heavy constant epsilon (IGHE)

Immunoglobulin heavy constant epsilon is the **constant region** of the heavy chain specific to immunoglobulin E (**IgE**) antibodies. Encoded by the *IGHE* gene on chromosome 14 in humans, this protein forms part of both secreted and membrane-bound forms of **IgE**, which are critical mediators in allergic responses. Structurally, each immunoglobulin molecule consists of two identical heavy chains (epsilon type for IgE) and two identical light chains linked by disulfide bonds; antigen specificity arises from variable domains at their N-terminal ends[2][3][4]. The **Fc portion**—the product encoded by IGHE—mediates effector functions through interaction with high-affinity (**FCER1A**) and low-affinity (**FCER2**) receptors on immune cells such as mast cells, basophils, eosinophils, macrophages, dendritic cells, and B lymphocytes. Upon cross-linking by allergens bound to antigen-specific variable regions on different molecules' Fab arms, these interactions trigger degranulation events leading to release of histamine and other mediators responsible for immediate hypersensitivity reactions including anaphylaxis[1][3]. In addition to its role in allergy pathogenesis—including asthma exacerbations—IgE also participates in host defense against parasitic infections via antibody-dependent cellular cytotoxicity mechanisms involving macrophages[3]. Measurement of total or allergen-specific serum IgE serves as a diagnostic biomarker for allergic diseases. Therapeutically targeting this molecule has proven effective in treating severe allergic asthma using monoclonal antibodies such as omalizumab that neutralize circulating free IgE before it can bind its cellular receptors. However, care must be taken due to potential impacts on host immunity against certain pathogens[1][4].

Other names

IgEIg epsilon chain C regionIGHE

Drugs like omalizumab bind to free circulating IgE at its Fc region, preventing it from interacting with high-affinity receptors on mast cells and basophils. This blocks allergen-induced cross-linking and subsequent cell activation/degranulation involved in allergic responses.