title: Blockade of proliferation and tumor necrosis factor-alpha production occurring during mixed lymphocyte reaction by interferon-gamma-specific natural antibodies contained in intravenous immunoglobulins.
abstract: The mechanism of action of intravenous immunoglobulins (IVIg) for prevention of graft rejection and graft-versus-host disease (GVHD) is poorly understood. Recently, it has been shown that these preparations contain natural antibodies directed toward interferon (IFN)-gamma. During mixed lymphocyte reaction (MLR), which constitutes an in vitro model of allograft rejection and GVHD, T cell recognition of HLA differences induces IFN-gamma release. This cytokine promotes T cell proliferation and acts as a macrophage-activating factor to provoke tumor necrosis factor-alpha secretion. The aim of the present work is to investigate the influence of IVIg on IFN-gamma production occurring during MLR and its subsequent impact on T cell proliferation and tumor necrosis factor (TNF)-alpha secretion. We tested IVIg preparations for the presence of anti-IFN-gamma and anti-TNF-alpha antibodies. High amounts of anti-IFN-gamma, but not anti-TNF-alpha antibodies, were found. IVIg addition at the initiation of culture resulted in IFN-gamma secretion blockade. Likewise, lymphocyte proliferation and TNF-alpha secretion were inhibited. This inhibition was reversed by the addition of recombinant human IFN-gamma. Furthermore, the inhibitory properties of IVIg were mimicked by an IFN-gamma-specific neutralizing monoclonal antibody. We conclude that the capacity of IVIg to inhibit proliferation and TNF-alpha release during MLR is due to IFN-gamma blockade by natural antibodies. This immunosuppressive mechanism could contribute to the effect of IVIg on prophylaxis of organ graft rejection and GVHD after allogeneic bone marrow transplantation.
authors.affiliation: Department of Immunology and Transfusion, Erasme Hospital, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: M
authors.initials: M
authors.lastname: Toungouz
authors.forename: C
authors.initials: C
authors.lastname: Denys
authors.forename: E
authors.initials: E
authors.lastname: Dupont
mesh_terms: D000906:Antibodies / Q000276:immunology / Q000627:therapeutic use; D002455:Cell Division / Q000187:drug effects; D006084:Graft Rejection / Q000276:immunology* / Q000517:prevention & control; D006086:Graft vs Host Disease / Q000276:immunology* / Q000517:prevention & control; D006801:Humans; D016756:Immunoglobulins, Intravenous / Q000276:immunology* / Q000627:therapeutic use; D066298:In Vitro Techniques; D007371:Interferon-gamma / Q000276:immunology*; D008213:Lymphocyte Activation / Q000276:immunology*; D008214:Lymphocytes / Q000276:immunology; D016377:Organ Transplantation; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000276:immunology*
chemical_list: D000906:Antibodies; D016756:Immunoglobulins, Intravenous; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma