High-affinity immunoglobulin epsilon receptor and Fc-gamma receptor (FcεRI and FcγR)

The FcεRI and Fcγ receptors are distinct families of cell-surface glycoproteins belonging to the immunoglobulin superfamily that play pivotal roles in the immune system by linking humoral responses to cellular effector functions. FcεRI is the high-affinity receptor for IgE, primarily found on mast cells and basophils, where its activation by IgE-antigen complexes triggers the release of inflammatory mediators such as histamine and leukotrienes, serving as the primary driver of type I hypersensitivity reactions [1][2]. Fcγ receptors (FcγRs) are a diverse group of receptors for IgG, categorized into activating (FcγRI, FcγRIIA, FcγRIIIA) and inhibitory (FcγRIIB) types, which collectively regulate processes such as phagocytosis, antibody-dependent cellular cytotoxicity (ADCC), and the modulation of B-cell activation [3][4]. These receptors are significant therapeutic targets; for example, the monoclonal antibody omalizumab binds to circulating IgE to prevent its interaction with FcεRI, thereby treating allergic asthma and chronic spontaneous urticaria [5]. In oncology, therapeutic antibodies are often glycoengineered or mutated in their Fc region to enhance their affinity for activating FcγRIIIA on natural killer cells, thereby boosting ADCC-mediated tumor clearance [6]. Dysregulation or genetic polymorphisms in these receptors are associated with various conditions, including systemic lupus erythematosus, rheumatoid arthritis, and severe allergic disorders [3][7].

Other names

Fc epsilon RIFc gamma receptorCD16CD32CD64High affinity IgE receptorIgG receptorFCGRFCER1

The primary mechanisms include the prevention of IgE binding to the high-affinity FcεRI receptor to inhibit mast cell degranulation, the competitive inhibition of IgG binding to activating Fcγ receptors using high-dose intravenous immunoglobulin, and the engineering of antibody Fc regions to increase affinity for activating FcγRIIIA (CD16A) to enhance antibody-dependent cellular cytotoxicity (ADCC) [3][5][6].