Recombinant Human CD23

CD23, also known as Fc-ε-RII/BLAST-2, is a low affinity IgE Fc receptor which belongs to the C-type lectin structural family and plays a role in the regulation of IgE synthesis and IgE mediated activities (1). It is distinct from the high affinity IgE receptors found on basophils and mast cells, which mediate allergic reactions. CD23 is found both as a transmembrane receptor protein and in a soluble form, which is generated by proteolytic cleavage of membrane bound CD23 (2). It is expressed on most mature, conventional B cells (but not on peritoneal CD5+ B cells), and can also be found on the surface of T cells, macrophages, platelets, eosinophils and EBV transformed B lymphoblasts (3). Expression of CD23 has also been detected in neoplastic cells from cases of B cell chronic Lymphocytic leukemia (4). CD23 is expressed by B cells in the follicular mantle but not by proliferating germinal centre cells.