Sialic acid-binding immunoglobulin-like lectin 2 (CD22 (Siglec-2))

Sialic acid-binding immunoglobulin-like lectin 2 (CD22, Siglec-2) is a cell surface receptor exclusively expressed on B lymphocytes, where it acts as an inhibitory co-receptor modulating immune responses. As a type I transmembrane protein in the immunoglobulin superfamily, it specifically binds sialic acid-containing glycans via its N-terminal V-set Ig domain. CD22 harbors intracellular ITIM motifs, which recruit SHP1/2 phosphatases upon tyrosine phosphorylation, suppressing B-cell receptor (BCR) signaling and preventing inappropriate activation. It plays a key role in immune tolerance, the regulation of B cell activation, and modulation of antibody production. Dysregulation or therapeutic targeting of CD22 can have significant effects in B cell-related disorders, including cancer and autoimmunity.

Other names

CD22Cluster of Differentiation 22Siglec-2BL-CAMSialic acid-binding Ig-like lectin 2

Antibody binding to CD22 can mediate B-cell depletion via antibody-dependent cellular cytotoxicity (ADCC) or direct apoptosis - Inhibition or modulation of B-cell receptor signaling (through ITIM motif recruitment of SHP1/2 phosphatases after phosphorylation) - Internalization and delivery of cytotoxic agents (immunotoxins)