title: CD59a deficient mice display reduced B cell activity and antibody production in response to T-dependent antigens.
abstract: CD59a is the primary regulator of membrane attack complex in mice. Recently, we have shown that CD59a-deficient (Cd59a-/-) mice exhibit enhanced CD4+ T cell responses. Here, we explored the effects of CD59a on B cell function and antibody production. Contrary to our expectations, Cd59a-/- mice showed a decreased humoral immune response to a T cell dependent antigen, sheep red blood cells. We found that the decreased humoral immune response was associated with a reduction in plasma cell number in vivo and reduced ability to respond to stimuli during in vitro culture experiments. Using MLR studies in which purified wild type or Cd59a-/- CD4+ T cells were mixed with purified B cells from each source, we found that the reduced B cell activation was largely due to the absence of CD59a on CD4+ T cells. Furthermore, a CD59a fusion protein bound specifically to mouse B cells, and enhanced B cell proliferation in a MLR, demonstrating that B cells express an as yet unidentified ligand for CD59a that aids in B cell activation.
authors.affiliation: Department of Medical Biochemistry and Immunology, School of Medicine, Cardiff University, Cardiff, United Kingdom.
authors.forename: Baalasubramanian
authors.initials: B
authors.lastname: Sivasankar
authors.forename: Rossen M
authors.initials: RM
authors.lastname: Donev
authors.forename: M Paula
authors.initials: MP
authors.lastname: Longhi
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Hughes
authors.forename: Ruth
authors.initials: R
authors.lastname: Davies
authors.forename: Duncan S
authors.initials: DS
authors.lastname: Cole
authors.forename: B Paul
authors.initials: BP
authors.lastname: Morgan
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Marchbank
mesh_terms: D000818:Animals; D000917:Antibody Formation; D017951:Antigen Presentation / Q000235:genetics; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D015704:CD4 Antigens / Q000235:genetics / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018957:CD59 Antigens / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D005434:Flow Cytometry; D017353:Gene Deletion; D008213:Lymphocyte Activation; D051379:Mice; D011485:Protein Binding
chemical_list: D015704:CD4 Antigens; D018957:CD59 Antigens