title: The CD9 tetraspanin is not required for the development of peripheral B cells or for humoral immunity.
abstract: The CD9 tetraspanin is known to be expressed at high levels on marginal zone (MZ) B cells, B-1 B cells, and plasma cells, and its expression is believed to be dependent on signals derived via Btk. In CD9 null mice, however, the development and survival of MZ B cells, B-1 B cells, and plasma cells all appear to be unaffected, and humoral immune responses to T-dependent and T-independent Ags are similar to those seen in wild-type littermate controls. In wild-type mice, CD9 levels may serve to distinguish between the presumed MZ precursor B cell population in the spleen and other IgD-expressing transitional B cells that express lower levels of CD21 and CD1d. These results suggest that CD9 is dispensable for B cell development and humoral immunity, but that this protein may serve as an additional marker for the presumed MZ precursor population of splenic B cells.
authors.affiliation: Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA 02129, USA.
authors.forename: Annaiah
authors.initials: A
authors.lastname: Cariappa
authors.forename: Tsipi
authors.initials: T
authors.lastname: Shoham
authors.forename: Haoyuan
authors.initials: H
authors.lastname: Liu
authors.forename: Shoshana
authors.initials: S
authors.lastname: Levy
authors.forename: Claude
authors.initials: C
authors.lastname: Boucheix
authors.forename: Shiv
authors.initials: S
authors.lastname: Pillai
mesh_terms: D000818:Animals; D000917:Antibody Formation; D015703:Antigens, CD / Q000502:physiology*; D001402:B-Lymphocytes / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000502:physiology*; D051379:Mice; D060245:Tetraspanin 29
chemical_list: D015703:Antigens, CD; C554870:Cd9 protein, mouse; D008562:Membrane Glycoproteins; D060245:Tetraspanin 29