title: IVIg prevents the in vitro activation of T cells by neutralizing the T cell activators.
abstract: Clinical observations in patients treated with IVIg revealed significant modulations in T cell populations and functions. However, it is unclear whether IVIg acts directly on activated T cells to suppress their functions. To clarify the exact mechanism of IVIg action, we studied its effect on T cells activated using anti-CD3/CD28 microbeads to mimic stimulatory signals provided by accessory cells. We report here that IVIg reduces T cell proliferation and cytokine secretion by interfering with the ability of anti-CD3/CD28 microbeads to deliver activating signals to T cells. We further show that the interference occurs between IVIg and anti-CD3/CD28 microbeads and does not involve T cells. In conclusion, our work suggests that T cells are not a direct target of IVIg and that the modulation of T cell populations and functions observed in treated patients is the indirect consequence of a direct effect of IVIg on accessory cells.
authors.affiliation: Department of Research and Development, Héma-Québec, Québec, Canada. lauriane.padet@hema-quebec.qc.ca
authors.forename: Lauriane
authors.initials: L
authors.lastname: Padet
authors.forename: Renée
authors.initials: R
authors.lastname: Bazin
mesh_terms: D057134:Antibodies, Neutralizing / Q000378:metabolism / Q000494:pharmacology; D018106:CD28 Antigens / Q000276:immunology / Q000378:metabolism; D017252:CD3 Complex / Q000276:immunology / Q000378:metabolism; D002478:Cells, Cultured; D006801:Humans; D016756:Immunoglobulins, Intravenous / Q000378:metabolism / Q000494:pharmacology*; D016130:Immunophenotyping; D008213:Lymphocyte Activation / Q000187:drug effects* / Q000276:immunology*; D011485:Protein Binding; D013601:T-Lymphocytes / Q000187:drug effects* / Q000276:immunology* / Q000378:metabolism
chemical_list: D057134:Antibodies, Neutralizing; D018106:CD28 Antigens; D017252:CD3 Complex; D016756:Immunoglobulins, Intravenous