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CD22为Ⅰ型跨膜糖蛋白，是唾液酸结合免疫球蛋白样凝集素家族成员。作为 B 细胞受体（BCR）的抑制性共受体，CD22对B细胞激活信号具有负性调节作用。 CD22能够与包含α－2，6连接唾液酸的糖蛋白配体特异性结合，抗原激活BCR，也使CD22胞质区免疫受体酪氨酸抑制基序中的酪氨酸迅速磷酸化，并激活下游信号分子抑制钙离子内流而减弱 BCR信号。 CD22参与 B 细胞的归巢过程。因CD22相对特异地表达于B细胞表面，已成为调节 B细胞免疫及治疗某些 B 细胞肿瘤的良好靶标。“,”CD22 is type I transmembrane glycoprotein,which is a member of the family of sialic acid-binding immunoglobulin-like lectins.As an inhibitory coreceptor of B cell receptor(BCR),CD22 negatively regulates activating signal of the B cell.CD22 specifically recognizes glycoprotein ligands containing α-2, 6-linked sialic acid.After activation of the BCR by antigen,tyrosine of immunoreceptor tyrosine-based inhibi-tor motirs located in the intracellular tail of the CD22 is rapidly phosphorylated.Then,downstream signaling molecules are activated to dampen BCR signal by reducing calcium ions flux .CD22 could be involved in hom-ing process of B cells.CD22 expresses relatively specially on the surface of B cells ,which makes it an attrac-tive target for regulation of immune response mediated by B cells and targeted therapy for B cell tumors .