title: Expression and function of CD22, a B-cell restricted molecule.
abstract: In this work, we studied the expression and function of CD22 in murine B cells. CD22 has been previously characterized as an activation marker of mature B lymphocytes. However, we found that CD22 is expressed early during the ontogeny of B cells in the bone marrow and spleen, and was found on B cells isolated from all the different lymphoid compartments. We also found that B cells stimulated through the B-cell antigen receptor (BCR), CD38 and CD40, upregulated CD22 expression to maximal levels within 24 h after stimulation, but that the levels of CD22 declined at later times (48 and 72 h). CD22 is rapidly phosphorylated after BCR signal transduction, and is believed to downregulate B-cell activation. In this study, we did not detect CD22 phosphorylation in activated B cells after CD38 or CD40 cross-linking, even though CD22 was clearly phosphorylated in the BCR-stimulated B cells. Consistent with this, we found no evidence of physical association between CD38 or CD40 and CD22 in B cells. The lack of association or phosphorylation of CD22 induced by CD38 and CD40 cross-linking indicates that CD22 may not downregulate the activation induced by these two molecules.
authors.affiliation: Department of Cellular Biology, Centro de Investigación y Estudios Avanzados del I.P.N., 07360 México D.F., México.
authors.forename: J E
authors.initials: JE
authors.lastname: Moyron-Quiroz
authors.forename: S
authors.initials: S
authors.lastname: Partida-Sánchez
authors.forename: R
authors.initials: R
authors.lastname: Donís-Hernández
authors.forename: C
authors.initials: C
authors.lastname: Sandoval-Montes
authors.forename: L
authors.initials: L
authors.lastname: Santos-Argumedo
mesh_terms: D036541:ADP-ribosyl Cyclase; D051997:ADP-ribosyl Cyclase 1; D000818:Animals; D015703:Antigens, CD / Q000032:analysis* / Q000502:physiology; D000943:Antigens, Differentiation / Q000502:physiology; D000944:Antigens, Differentiation, B-Lymphocyte / Q000032:analysis* / Q000502:physiology; D001402:B-Lymphocytes / Q000737:chemistry* / Q000502:physiology; D001853:Bone Marrow / Q000737:chemistry; D019013:CD40 Antigens / Q000502:physiology; D015815:Cell Adhesion Molecules; D037102:Lectins; D008562:Membrane Glycoproteins; D051379:Mice; D008807:Mice, Inbred BALB C; D009244:NAD+ Nucleosidase / Q000502:physiology; D010766:Phosphorylation; D011947:Receptors, Antigen, B-Cell / Q000502:physiology; D051918:Sialic Acid Binding Ig-like Lectin 2
chemical_list: D015703:Antigens, CD; D000943:Antigens, Differentiation; D000944:Antigens, Differentiation, B-Lymphocyte; D019013:CD40 Antigens; C497868:Cd22 protein, mouse; D015815:Cell Adhesion Molecules; D037102:Lectins; D008562:Membrane Glycoproteins; D011947:Receptors, Antigen, B-Cell; D051918:Sialic Acid Binding Ig-like Lectin 2; D036541:ADP-ribosyl Cyclase; C498155:Cd38 protein, mouse; D009244:NAD+ Nucleosidase; D051997:ADP-ribosyl Cyclase 1