CD22

What is CD22?

CD22, also known as Siglec-2, is mainly expressed in mature B cells, and is a cell surface adhesion molecule that regulates B cell activation, which helps B cells to regulate the sensitivity of antigen response.

What is The Function of CD22?

B-cell receptor CD22 is a protein in humans that is encoded by CD22 gene. It is involved series of physiological process. CD22 binds to an array of ligands including a diverse group of sialic acid-containing molecules expressed by lymphocytes, neutrophils, monocytes, erythrocytes, and other nonhematopoietic cell types, CD22-mediated interactions with other cell types have been studied extensively.

In addition to its role as an adhesion molecule, CD22 has been most commonly known to modulate signaling thresholds for B-cell activation. The ability of CD22 to modulate B-cell signaling is dependent on its proximity to BCR.

CD22 and B-cell Signaling

The ability of CD22 to modulate B-cell signaling is dependent on its proximity to the BCR and is governed by extracellular interactions. Upon B-cell receptor (BCR) cross-linking and translocation to lipid rafts, Lyn phosphorylates the immune-receptor tyrosine-based activation motif tyrosine residues of immunoglobulin a/b. This creates docking sites for other protein tyrosine kinases such as spleen tyrosine kinase (Syk), which in turn phosphorylate and recruit the adaptor molecule BLNK (B-cell linker protein). < a class="link-hover text-main" href="https://www.cusabio.com/Polyclonal-Antibody/BLNK-Antibody-12554602.html">BLNK forms a scaffold for the association of numerous signaling components, including Vav-1, Btk (Bruton’s tyrosine kinase), and phospholipase Cc2 (PLCγ 2).

CD22 and Disease

The CD22 molecule inhibits the signal produced by the BCR complex recognition antigen. This inhibition was further validated in studies of CD22-deficient mice. B cells in CD22-deficient mice showed mild activation, the number of mature B cells with high IgD and low IgM increased, B cell surface IgM (sIgM) levels decreased, IgM secretion increased and the expression of MHC class II molecules increased. As an antigen that limits B cells, CD22 provides an effective target for the treatment of autoimmune diseases and B cell dysregulation in blood cancer.

CD22 and CAR-T Cell Therapy

Taking CD22 as a target, tumor immunotherapy has become one of the hot research topics. Currently, immune-targeting therapy for CD22 molecules, in addition to therapeutic antibodies, also has CAR-T cell therapy. As of November 2019, although only two CD-related antibody drugs have been approved for marketing, including Inotuzumab ozogamicin (launched by WYETH PHARMS INC) and Moxetumomab Pasudotox (launched by ASTRAZENECA AB). Moreover, there are nearly 108 clinical studies on CD22 CAR-T cell therapy and antibody drugs.

Regard reading: CD22- What A Powerful Co-receptor of B Cell Receptor

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