title: Reduced T-dependent humoral immunity in CD20-deficient mice.
abstract: CD20 is a tetraspanning membrane protein expressed on B lymphocytes. CD20 deficiency in both mice and humans has recently been shown to have deleterious effects on Ab responses to T-independent Ags; however, no effect on T-dependent immunity has been reported. In this study, we used a Cd20⁻/⁻ mouse line to evaluate Ab responses to adeno-associated virus and SRBCs. The neutralizing Ab response to adeno-associated virus was significantly reduced by CD20 deficiency; both primary (IgM) and secondary (IgG1 and IgG2b) responses to SRBC were also reduced in Cd20⁻/⁻ mice, and this was associated with a reduction in the number of germinal center B cells. A successful humoral response requires the integration of intracellular signaling networks that critically rely on calcium mobilization. In this article, we confirm that BCR-mediated calcium mobilization is reduced in Cd20⁻/⁻ murine B cells after BCR stimulation in vitro, and further show that the reduction is due to an effect on calcium influx rather than calcium release from intracellular stores. Calcium-dependent upregulation of CD69 was impaired in CD20-deficient B cells, as was upregulation of CD86. Altogether, this study demonstrates a role for CD20 in B cell activation and T-dependent humoral immunity.
authors: Department of Biochemistry and Molecular Biology, University of Calgary, Alberta T2N 4N1, Canada. jdeans@ucalgary.ca
authors: Deyaa El Deen
authors: DE
authors: Morsy
authors: Ratna
authors: R
authors: Sanyal
authors: Anne K
authors: AK
authors: Zaiss
authors: Rucha
authors: R
authors: Deo
authors: Dan A
authors: DA
authors: Muruve
authors: Julie P
authors: JP
authors: Deans
mesh_terms: D000818:Animals; D018951:Antigens, CD20 / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D056724:Immunity, Humoral / Q000276:immunology*; D007150:Immunohistochemistry; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D018345:Mice, Knockout; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D018951:Antigens, CD20