B-cell receptor CD22 (CD22)

CD22 is a transmembrane glycoprotein receptor and a member of the immunoglobulin superfamily, predominantly expressed on the surface of mature B lymphocytes[2][4][5][7]. It binds sialic acid-containing glycans via its N-terminal Ig domain and acts as an inhibitory co-receptor that regulates B-cell receptor (BCR) signaling by recruiting cytoplasmic phosphatases (e.g., SHP-1) upon tyrosine phosphorylation in response to antigen stimulation[1][3][4]. CD22 thereby dampens BCR-mediated signaling, sets activation thresholds in B cells, and plays a critical role in immune tolerance and prevention of autoimmunity[1][2][4]. Its targeted modulation is clinically relevant in autoimmunity and B-cell malignancies, and it is the molecular target of several approved or investigational therapeutic antibodies and antibody-drug conjugates[4][5].

Other names

Cluster of differentiation 22Sialic acid-binding Ig-like lectin 2 (Siglec-2)B-lymphocyte cell adhesion moleculeT-cell surface antigen Leu-14[2][5][7]

Monoclonal antibodies binding to CD22 block BCR signaling or mediate antibody-dependent cell cytotoxicity (ADCC) Antibody-drug conjugates deliver cytotoxins to CD22-expressing B cells Target engagement leads to internalization and inhibition of B-cell survival[4][5]