Fc fragment of IgE receptor II (FCER2)

Fc fragment of IgE receptor II (FCER2, commonly known as CD23) is a membrane-bound and soluble low-affinity receptor for IgE, structurally classified as a C-type lectin and expressed primarily on B cells, with additional expression on activated macrophages, eosinophils, dendritic cells, and platelets[1][2][3]. CD23 regulates IgE homeostasis by modulating B cell differentiation and IgE production, and facilitates transcytosis of IgE and IgE-antigen complexes, impacting both allergic inflammation and immune surveillance[1][2][4]. Clinically, it is relevant as a diagnostic biomarker for certain B cell malignancies and has been explored as a therapeutic target in allergy and leukemia; however, clinical development of targeted therapies such as lumiliximab was discontinued due to lack of efficacy[3]. FCER2 gene variants can influence disease risk and severity, particularly in allergic conditions and asthma[2].

Other names

CD23Fc epsilon receptor IIFcεRIILow affinity immunoglobulin epsilon Fc receptorC-type lectin domain family 4 member JCLEC4JCD23ABLAST-2IGEBFFCE2

Antibody binding to CD23 blocks or modulates IgE-CD23 interaction, thereby reducing IgE-mediated allergic responses or modifying B cell signal transduction and survival[3].