More probably, thein vivomodulation of T cell populations observed in IVIg-treated patients is a consequence of the effect of IVIg on APCs [17]

More probably, thein vivomodulation of T cell populations observed in IVIg-treated patients is a consequence of the effect of IVIg on APCs [17]. results challenge the previously widely accepted notion that IVIg exerts its anti-inflammatory effects by acting directly on T cells and suggest that effects of IVIg observed in treated patients are rather a consequence of the recently reported inhibitory effect Y-33075 of IVIg on antigen presentation. Keywords:glycan, IVIg, lectin, phytohaemagglutinin, T cell activation == Introduction Y-33075 == Intravenous immunoglobulin (IVIg) is a therapeutic preparation of human IgG derived from the plasma of thousands of healthy donors and was used initially as replacement therapy in patients with primary or secondary immunodeficiencies. In the early 1980s, infusion of high doses of IVIg was shown to produce therapeutic effects in patients suffering from immune thrombocytopenia (ITP) by attenuating platelet clearance [1]. IVIg is now used commonly to treat a diversity of autoimmune and inflammatory diseases [24]. However, the mechanisms by which IVIg produces anti-inflammatory effects in such a diversity of diseases are still not well defined and require further investigation [5,6]. T cells are important players in normal immunity, but also play a critical role in the development and persistence of autoimmunity [79]. Clinical studies conducted on IVIg-treated patients have revealed significant modulations of T cell functions in these patients. More precisely, these studies have shown that IVIg influences the ratio of T helper type 1 (Th1)/Th2 cells, induces Th0 or Th2 responses and modifies the cytokine manifestation profile in individuals suffering from a diversity of Y-33075 inflammatory disorders [1014]. To understand the mechanisms by which IVIg modulates T cell populations and their pattern of cytokine secretion, a number of groups of investigators possess performedin vitroassays in which purified T cells were triggered with mitogenic lectins in Y-33075 the presence of IVIg. Conclusions derived from these studies indicated that IVIg has a direct effect on triggered T cell functions, leading to inhibition of proliferation and cytokine secretion or induction of Rabbit Polyclonal to OR51E1 T cell apoptosis. However, a direct effect of IVIg on T cells was questioned following reports from Achironet al. [15] and Skanse-Saphiret al. [16]. In addition, work from our laboratory has established recently that IVIg has no direct effect on antigen-activated T cells, but rather modulates the functions of antigen-specific T cells by reducing the activity of antigen-presenting cells (APCs) [17]. These recent observations within the absence of a direct effect of IVIg on T cells prompted us to re-examine the mechanisms by which IVIg interfered with the functions of T cells triggered with lectins. Y-33075 Our results reveal the inhibition of cytokine secretion or proliferation reported previously for lectin-activated T cells in the presence of IVIg is due to a direct conversation of IVIg with lectins, leading to neutralization of their mitogenic or stimulatory potential, rather than a direct effect of IVIg on T cells. == Materials and methods == == Cells and reagents == The human being Jurkat T cell collection (clone D11) was from American Type Tradition Collection (Rockville, MD, USA) and was mycoplasma free. Jurkat T cells were cultured in RPMI-1640 medium supplemented with 10% fetal bovine serum (FBS) ultra-low IgG, 1 mmsodium pyruvate (all from Invitrogen Canada Inc., Burlington, Canada), 100 devices/ml of penicillin and 100 g/ml of streptomycin (Sigma-Aldrich Canada Ltd, Toronto, Canada). IVIg (10%; Gamunex) and human being serum albumin (HSA) were from Talecris Biotherapeutics Ltd (Mississauga, Canada). IVIg and HSA were dialysed against RPMI-1640 medium, sterile-filtered and stored at 80C until use. Phytohaemagglutin-L (PHA), concanavalin A (Con A) and pokeweed mitogen (PWM) were all purchased from Sigma-Aldrich. PHA conjugated to AlexaFluor 488 (PHA-AF488) was from Invitrogen Canada Inc. Human being peripheral blood mononuclear cells (PBMC) were isolated by density centrifugation over Ficoll-Paque (GE Healthcare Bio-Sciences, Inc., Baie d’Urf, Canada) starting with whole blood collected from healthy volunteers after knowledgeable consent. ==.