title: Analysis of murine CD22 during B cell development: CD22 is expressed on B cell progenitors prior to IgM.
abstract: CD22 is a B cell-restricted glycoprotein involved in cell adhesion and signaling. Since CD22 is likely to play an important role in interactions between B cells and other cells, and in regulating signaling thresholds, we characterized the expression of murine CD22 during different stages of B cell development. In contrast to previous reports, we show that CD22 is expressed on B cell progenitors prior to expression of IgM. IL-7-responsive B cell precursors from the fetal liver and early B lineage cells (B220+IgM-) from the bone marrow both express a low density of surface CD22. The majority of the earliest B cell progenitors (B220+IgM-CD43+) in the bone marrow, however, do not express CD22. As B cells mature, the density of CD22 molecules on the cell surface increases. B220brightIgM+ bone marrow cells express high levels of CD22, as do splenic B cells. The correlation of CD22 levels with B cell maturation is replicated in an in vitro culture system, which distinguishes stages of B cell development based on function. Following activation of mature resting splenic B cells with anti-mu mAb or lipopolysaccharide (LPS), levels of CD22 decrease. Finally, we show that the addition of anti-CD22 mAb augments the proliferative response of both anti-mu- and LPS-stimulated B cells, suggesting a role for CD22 in diverse signaling pathways.
authors.affiliation: Wellesley Hospital Research Institute, Wellesley Central Hospital, Toronto, Ontario, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Stoddart
authors.forename: R J
authors.initials: RJ
authors.lastname: Ray
authors.forename: C J
authors.initials: CJ
authors.lastname: Paige
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D000944:Antigens, Differentiation, B-Lymphocyte / Q000378:metabolism*; D001402:B-Lymphocytes / Q000166:cytology* / Q000276:immunology*; D015815:Cell Adhesion Molecules; D002454:Cell Differentiation; D005260:Female; D005333:Fetus / Q000166:cytology / Q000276:immunology; D006410:Hematopoiesis; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000276:immunology*; D007075:Immunoglobulin M / Q000096:biosynthesis; D037102:Lectins; D008099:Liver / Q000166:cytology; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D011247:Pregnancy; D051918:Sialic Acid Binding Ig-like Lectin 2; D015398:Signal Transduction
chemical_list: D015703:Antigens, CD; D000944:Antigens, Differentiation, B-Lymphocyte; C497868:Cd22 protein, mouse; D015815:Cell Adhesion Molecules; D007075:Immunoglobulin M; D037102:Lectins; D051918:Sialic Acid Binding Ig-like Lectin 2