Sialic acid-binding Ig-like lectin 2 (Siglec-2 (also known as CD22))

Sialic acid-binding Ig-like lectin 2, commonly known as Siglec-2 or CD22, is a cell surface protein belonging to the immunoglobulin superfamily and functions as an inhibitory receptor predominantly expressed on B lymphocytes[4][3]. Structurally, it is a type I transmembrane receptor with extracellular immunoglobulin-like domains that specifically recognize sialic acid-containing glycans, mediating protein-carbohydrate interactions at the cell surface[1][6]. The cytoplasmic region contains immunoreceptor tyrosine-based inhibitory motifs (ITIMs) that, upon phosphorylation, recruit SHP-1 and SHP-2 phosphatases to negatively regulate B cell receptor (BCR) signaling, thereby maintaining tolerance, regulating immune activation, and preventing autoimmunity[5][7][8]. CD22 is a clinically important marker and therapeutic target in B-cell lymphomas and leukemias, with multiple approved and investigational antibody-based therapeutics designed to exploit its restricted expression on B cells[5].

Other names

CD22Siglec-2B-cell receptor CD22BL-CAMSIGLEC2sialic acid binding Ig-like lectin 2

Antibody binding to CD22 induces B cell depletion by antibody-mediated cytotoxicity or toxin delivery; Inhibition or modulation of B cell activity via ITIM signaling domains; Drug conjugates deliver cytotoxic agents to CD22+ B cells