Description
Product Characteristics: Heterodimer composed of two glycoprotein chains of 130 - 140 kDa molecular weight glycoprotein chains The antigen is present as both a cytoplasmic and membrane antigen on B lymphocytes. The CD22 antigen is expressed in the cytoplasm of the majority of B lymphocytes including early B progenitor cells. Antigen expression appears at an early stage in B lymphocyte differentiation at approximately the same stage as the CD19 antigen. Surface expression of the CD22 antigen by B lymphocytes is variable. Circulating B lymphocytes are CD22+ and follicular mantle and marginal zone B lymphocytes show strong binding of CBL147. Germinal centre B cells exhibit only weak expression of the CD22 antigen. The CD22 antigen is poorly expressed by non-T ALL cells and by a proportion of B- CLL cells. Hairy cell leukeamia cells have been demonstrated to strongly express the CD22 antigen.
Target Information: Mediates B-cell B-cell interactions. May be involved in the localization of B-cells in lymphoid tissues. Binds sialylated glycoproteins\, one of which is CD45. Preferentially binds to alpha-2,6-linked sialic acid. The sialic acid recognition site can be masked by cis interactions with sialic acids on the same cell surface. Upon ligand induced tyrosine phosphorylation in the immune response seems to be involved in regulation of B-cell antigen receptor signaling. Plays a role in positive regulation through interaction with Src family tyrosine kinases and may also act as an inhibitory receptor by recruiting cytoplasmic phosphatases via their SH2 domains that block signal transduction through dephosphorylation of signaling molecules