Background：The Cy34.1 monoclonal antibody specifically binds to the B-lymphocyte differentiation antigen CD22 on strains having the Lyb-8.2 alloantigen （e.g., A, BALB/c, CBA, C3H/He, C57BL, C57L, C58, SJL, SWR, but not AKR, DBA/1, DBA/2, NZB, PL）. CD22 is expressed at high levels on mature peripheral B lymphocytes （follicular and marginal zone）, B-1 cells （CD5+ B cells）, and plasma cells. It is a member of the Ig gene superfamily and associates with the B-cell antigen receptor. Its sialic acid- binding immunoglobulin-like lectin （siglec） extracellular region mediates B-cell adhesion to ligands on endothelial cells in the bone marrow. Its intracellular domain is phosphorylated after cross-linking of antigen receptor or MHC class II antigen. It is involved in negative regulation of B-cell activation and protection from autoimmunity. B-cell proliferative responses to LPS or anti-mouse Ig μ chain are augmented in the presence of Cy34.1 mAb.
