Low affinity immunoglobulin epsilon Fc receptor (CD23) (CD23)

The low-affinity immunoglobulin epsilon Fc receptor, commonly known as CD23 or FcεRII, is a type II transmembrane C-type lectin that plays a critical role in the regulation of IgE-mediated immune responses (UniProt P06734) [1]. Unlike the high-affinity receptor FcεRI, CD23 is primarily expressed on B cells and follicular dendritic cells, where it exists as a homotrimer (PubMed: 8271750) [2, 3]. The complex formed by allergen-specific IgE bound to CD23 on B cells is essential for facilitated antigen presentation (FAP), a process that enhances the uptake of allergens and their subsequent presentation to T cells, thereby amplifying allergic inflammation (PubMed: 32311158) [2]. CD23 also undergoes proteolytic cleavage to release soluble CD23 (sCD23), which can act as a cytokine to either stimulate or inhibit further IgE synthesis depending on its oligomeric state (NCBI Gene: 2204) [1, 6]. Therapeutic strategies targeting this system include monoclonal antibodies like lumiliximab, which binds CD23 to treat B-cell malignancies, and omalizumab, which binds free IgE to prevent its interaction with both CD23 and FcεRI in allergic asthma (DrugBank DB04902, DB00043) [4, 5].

Other names

Fc epsilon receptor IIFCER2Lymphocyte IgE receptorBLAST-2Immunoglobulin E-binding factor

Monoclonal antibodies target the CD23 receptor or its ligand (IgE) to disrupt the IgE-mediated feedback loop and inhibit facilitated antigen presentation to T cells (PubMed: 32311158, DrugBank DB04902) [2, 4].