title: In vitro induction of IgG anti-DNA antibody from high density B cells of systemic lupus erythematosus patients by an HLA DR-restricted T cell clone.
abstract: An HLA-DR restricted T cell clone (26G11) which recognized a lymphoid cell-derived autoantigen associated with DR4 molecule was shown to induce not only autologous but also allogenic DR4+ B cells to produce large amounts of antibodies of the IgG and IgM classes. Using the helper activity of this clone, we investigated the mechanism of anti-DNA antibody production in DR-matched patients with systemic lupus erythematosus (SLE). When cultured with 26G11 cells, B cells from DR-matched normal control subjects produced large amounts of IgM anti-DNA antibody, but did not produce IgG anti-DNA antibody which is thought to have a pathological role in SLE. In contrast, B cells from DR-matched patients with active SLE spontaneously produced a fairly large amount of IgG anti-DNA antibody, and the production was augmented by the T cell clone. Little IgG anti-DNA antibody was produced by the B cells of patients with inactive SLE in either the presence or absence of T cell clone. We next fractionated B cells into low density B (LD-B) and high density B (HD-B) cells by centrifugation on discontinuous Percoll density gradients. IgG anti-DNA antibody was spontaneously produced by LD-B cells of active SLE patients but not by those either of inactive SLE patients or normal controls. On the other hand, although IgG anti-DNA antibody was not spontaneously produced by the HD-B cells of both active and inactive SLE patients, it could easily be induced by their culture with the T cell clone. Our results clearly show the existence of IgG anti-DNA antibody-producing B cells in the peripheral blood of SLE patients irrespective of their disease activity and suggest that autoreactive T cells may play a pathogenic role in SLE through the induction of autoantibody production.
authors.affiliation: Second Division of Internal Medicine, School of Medicine, Kyoto University, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Murakami
authors.forename: S
authors.initials: S
authors.lastname: Kumagai
authors.forename: M
authors.initials: M
authors.lastname: Sugita
authors.forename: K
authors.initials: K
authors.lastname: Iwai
authors.forename: H
authors.initials: H
authors.lastname: Imura
mesh_terms: D000974:Antibodies, Antinuclear / Q000096:biosynthesis*; D001402:B-Lymphocytes / Q000276:immunology*; D015804:HLA-DR4 Antigen / Q000276:immunology; D006801:Humans; D007074:Immunoglobulin G / Q000096:biosynthesis*; D066298:In Vitro Techniques; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D008213:Lymphocyte Activation; D008211:Lymphocyte Cooperation; D013601:T-Lymphocytes / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology
chemical_list: D000974:Antibodies, Antinuclear; D015804:HLA-DR4 Antigen; D007074:Immunoglobulin G