title: B-B cell interactions in the spontaneous activation of B cells in autoimmune NZB mice.
abstract: We analyzed the mechanism of spontaneous B cell activation in lupus mice by using anticlass-II antibody in vitro. The in vitro culture of B cells from old NZB mice markedly produced Ig without any stimulation, while B cells from NZW mice did not. The addition of anticlass-II antibody (anti-Iad antibody) to the culture inhibited Ig production of NZB B cells in a concentration-dependent manner. On the other hand, the addition of anticlass-I antibody (anti-H-2Dd antibody) and anticlass-II antibody with different specificity (anti-Iak) gave no effect on the Ig production of NZB B cells. When mitomycin C-treated B cells were added to in vitro culture of responder B cells as a stimulator, Ig production of responder B cells was enhanced in a concentration-dependent manner. However, the enhancing effect of the stimulator B cells was abrogated by the pretreatment with anticlass-II antibody. The stimulator B-cell activity to NZB B cells was marked in NZB B cells, moderate in NZB/W F1 B cells, and weak in NZW B cells. Furthermore, the stimulator B-cell activity with regard to NZB B cells was marked in old female NZB B cells, moderate in old male NZB B cells, and weak in young NZB B cells. The expression of class II antigens on the surface of old female NZB B cells was significantly higher than that of old male NZB and young NZB B cells. These results suggest that in lupus mice the spontaneous B-cell activation is induced by an abnormal B-B cell interaction mediated by class II antigens.
authors.affiliation: First Department of Internal Medicine, University of Occupational and Environmental Health, School of Medicine, Fukuoka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Saito
authors.forename: Y
authors.initials: Y
authors.lastname: Tanaka
authors.forename: T
authors.initials: T
authors.lastname: Ota
authors.forename: S
authors.initials: S
authors.lastname: Eto
authors.forename: U
authors.initials: U
authors.lastname: Yamashita
mesh_terms: D000818:Animals; D015551:Autoimmunity / Q000276:immunology*; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D004195:Disease Models, Animal; D005260:Female; D007074:Immunoglobulin G / Q000096:biosynthesis; D008177:Lupus Vulgaris / Q000276:immunology; D008213:Lymphocyte Activation; D008211:Lymphocyte Cooperation / Q000276:immunology*; D008285:Major Histocompatibility Complex / Q000276:immunology*; D051379:Mice; D008814:Mice, Inbred NZB; D016685:Mitomycin / Q000494:pharmacology
chemical_list: D007074:Immunoglobulin G; D016685:Mitomycin