Cluster of Differentiation 22 (CD22)

Cluster of Differentiation 22 (CD22), also known as Siglec-2, is a transmembrane sialoglycoprotein that belongs to the immunoglobulin superfamily and the SIGLEC family of lectins. CD22 is predominantly expressed on the surface of mature B lymphocytes and, to a lesser extent, on some immature B cells. It plays a critical role in regulating B-cell function, survival, proliferation, and intercellular adhesion. It acts as an inhibitory co-receptor for the B-cell receptor (BCR) complex. It helps maintain baseline inhibition of signaling pathways within humoral immunity—preventing overactivation that could lead to autoimmunity or dysregulated immune responses. CD22 is an attractive therapeutic target because it is restricted mainly to the B-cell lineage.

Other names

Siglec-2

Targeted therapies exploit CD22’s restricted expression pattern by delivering cytotoxic agents directly into malignant/dysregulated B-cells.