Inhibitory Effect Of Intravenous Immunoglobulin Research Articles

Inhibitory Effect of IVIG on IL-17 Production by Th17 Cells is Independent of Anti-IL-17 Antibodies in the Immunoglobulin Preparations

Th17 cells and their cytokines play a critical role in the pathogenesis of various autoimmune and inflammatory diseases. Recently, we have demonstrated that intravenous immunoglobulin (IVIG) suppresses differentiation, amplification, and functions of human Th17 cells. In this report we investigated whether IVIG inhibits IL-17 production by Th17 cells cultured in the presence of IL-23 and whether the inhibitory effect of IVIG on IL-17 production implicates anti-IL-17 antibodies. Naive CD4(+) T cells were stimulated in the presence of TGF-β, IL-21, and IL-23 for the differentiation of Th17 cells. Memory CD4(+) T cells were stimulated with IL-1β, IL-6, and IL-23 for the amplification of Th17 cells. IVIG (0.15mM) was added to the cells 12h after initiation of cultures. IL-17A cytokine and anti-IL-17 antibodies were measured by ELISA. IL-23 did not deter the inhibitory effect of IVIG on IL-17 production from the differentiating and expanding Th17 cells. Further, suppression of IL-17 by IVIG did not implicate anti-IL-17 antibodies in the immunoglobulin preparations. The effect of IVIG on the inhibition of IL-17 production by Th17 cells is a consequence of modulation of Th17 cells and their intracellular signaling pathways and not due to passive neutralization of IL-17 by anti-IL-17 antibodies in the immunoglobulin preparations.

Indirect inhibition of in vivo and in vitro T-cell responses by intravenous immunoglobulins due to impaired antigen presentation

AbstractSeveral clinical studies done with intravenous immunoglobulin (IVIg)–treated autoimmune patients as well as several in vitro studies have revealed that IVIg can reduce polyclonal T-cell activation and modify their cytokine secretion pattern. However, their effect on (auto)antigen-specific T-cell responses has never been addressed directly. In the present work, we used an in vivo model of induction of antigen-specific T-cell responses and an in vitro antigen presentation system to study the effects of IVIg on T-cell responses. The results obtained showed that IVIg inhibited both the in vivo and in vitro antigen-specific T-cell responses but that this effect was the indirect consequence of a reduction in the antigen presentation ability of antigen-presenting cells. The inhibitory effect of IVIg was FcγRIIb-independent, suggesting that IVIg must interfere with activating FcγRs expressed on antigen-presenting cells to reduce their ability to present antigens. Such inhibition of T-cell responses by reducing antigen presentation may therefore contribute to the well-known anti-inflammatory effects of IVIg in autoimmune diseases.

An immunoglobulin agent (IVIG) inhibits NF-?B activation in cultured endothelial cells of coronary arteries in vitro

Kawasaki disease (KD) is an acute febrile vasculitis of unknown etiology that may lead to cardiovascular disorders. High-dose intravenous immunoglobulin (IVIG) therapy is well established as a standard therapy for KD. Tumor necrosis factor-alpha (TNF-alpha) is responsible for the pathogenesis of acute KD. We examined whether or not IVIG inhibits TNF-alpha-induced activation of transcription factor NF-kappaB, a factor that is essential for the expression of proinflammatory cytokines, in human coronary artery endothelial cells (CAEC). The inhibitory effect of IVIG on NF-kappaB activation induced by TNF-alpha was evaluated by Western blot analysis and ELISA. Moreover, the inhibitory effects of IVIG on IkappaBalpha degradation, interleukin-6 (IL-6) production, and E-selectin expression induced by TNF-alpha were evaluated by Western blot analysis, ELISA, and flow cytometry, respectively. Western blot analysis and ELISA demonstrated that IVIG inhibits NF-kappaB activation induced by TNF-alpha in CAEC. Moreover, IVIG inhibited IkappaBalpha degradation, IL-6 production, and E-selectin expression induced by TNF-alpha in CAEC. The data suggest that IVIG inhibits NF-kappaB activation induced by TNF-alpha in CAEC, thereby possibly modulating IL-6 production and E-selectin expression.

Intravenous immunoglobulin inhibits NF-kappaB activation and affects Fcgamma receptor expression in monocytes/macrophages.

High-dose intravenous immunoglobulin (IVIG) therapy is well established as a standard therapy for Kawasaki disease (KD) that reduces the risk of developing coronary artery aneurysms. Activation of monocytes/macrophages and tumor necrosis factor-alpha (TNF-alpha) activity are responsible for severe vascular injury in acute KD. We examined whether or not IVIG inhibits TNF-alpha-induced activation of transcription factor NF-kappaB, a factor that is essential for the expression of proinflammatory cytokines, in human monocytic U-937 cells. The inhibitory effect of IVIG on NF-kappaB activation induced by TNF-alpha was evaluated by Western blotting and flow cytometry. In addition, we examined the effect of IVIG on the expression of FcgammaIII (CD16) and FcgammaRIIb (CD32b) in U-937 cells and peripheral blood CD14+ monocytes/macrophages by flow cytometry. Western blotting demonstrated that IVIG inhibits NF-kappaB activation in U-937 cells, and flow cytometry that IVIG inhibits NF-kappaB activation in U-937 cells in a dose-related manner. Western blotting of cytoplasmic extracts of U-937 cells revealed that IVIG inhibited degradation of the IkappaBalpha protein. Moreover, flow cytometry demonstrated that IVIG decreased the expression of FcgammaRIII in U-937 cells and peripheral blood CD14+ monocytes/macrophages. However, Western blotting revealed that IVIG did not affect the quantity of FcgammaRIII protein, and PCR that IVIG did not affect the quantity of FcgammaRIII mRNA in the cells. These findings suggest that IVIG inhibits TNF-alpha-induced NF-kappaB activation in monocytes/macrophages, and blocks FcgammaRIII on the membranes of monocytes/macrophages.

Modulation of immunoglobulin production and cytokine mRNA expression in peripheral blood mononuclear cells by intravenous immunoglobulin.

Intravenous immunoglobulin (IVIG) has the potential to regulate Ig production, but the mechanism(s) responsible for this effect is unknown. In experiments reported here, we examined the ability of IVIG to regulate Ig production in human peripheral blood mononuclear cells (PBMCs) stimulated with pokeweed mitogen (PWM). IVIG (2-10 mg/ml) showed a potent (80-85%) inhibition of PWM-stimulated IgG, IgM, and IgA production. To determine more precisely how IVIG mediated the inhibition of Ig production, we studied Ig promoting cytokine gene expression after PWM stimulation with or without IVIG (2 and 10 mg/ml) using dot-blot techniques. RNA was isolated from PBMCs at predetermined time points and probed with cDNAs specific for human cytokines (IL-1 beta, IL-2, IL-2R, IL-4, IL-5, IL-6, gamma-IFN, and TNF-alpha). IL-6 mRNA accumulation was maximal at 4.5 hr post-PWM stimulation and was inhibited 64-75% when IVIG (10 mg/ml) was present. gamma-IFN mRNA levels peaked at 72 hr poststimulation and were also 68-75% inhibited by IVIG. IL-2 mRNA levels peaked at 4.5 hr and were 23-46% inhibited by IVIG. The inhibitory effect of IVIG on production of these cytokines (IL-6 and gamma-IFN) was also observed at the protein level in sonicated PBMCs after incubation with PWM and IVIG. The mRNA levels for other cytokines were not or only minimally inhibited by IVIG. Addition of IL-6, gamma-IFN, or IL-2 partially restored Ig production in IVIG-treated PWM-stimulated cultures, suggesting that inhibition of other cytokines or another mechanism(s) independent of cytokine inhibition might also be involved, although inhibition of IL-6, gamma-IFN, and IL-2 may be one of the critical factors in the suppression of Ig production by IVIG.