Varying effects of intravenous immunoglobulin on mononuclear cell proliferation in vitro

Effects of Intravenous Immunoglobulins on Peripheral Blood Mononuclear Cell Activation in Vitro

The therapeutic effects of intravenous immunoglobulins (IVIGs) on different chronic inflammatory and autoimmune diseases is well appreciated, though clinical studies with high-evidence levels are largely missing. Similar to the broad spectrum of diseases and their underlying etiopathogenic background, the mechanisms of action seem heterogenous and multifold. Several studies addressing in vitro and in vivo effects of IVIG on various immunological parameters have been described with partly contradictory results. In this study immunoglobulins and stabilizers present in commercial IVIG preparations were studied in regard to the in vitro proliferation and cytokine production of peripheral blood mononuclear cells when stimulated with phytohemagglutinin (PHA), interleukin 2, and tetanus toxoid. Whereas the immunoglobulins stimulate the proliferation of PBMCs and decrease IFNgamma secretion, stabilizers of IVIG seem to inhibit the proliferation of PBMCs while increasing the secretion of IFN gamma. These effects have to be taken into account when balancing the impact of IVIG dosage and infusion intervals and relating them to clinical side effects and therapeutic efficacy.

Kawasaki disease may be a hyperimmune reaction of genetically susceptible children to variants of normal environmental flora

Kawasaki disease (KD) is an acute febrile systemic vasculitis of unknown etiology that occurs predominantly in children <5 years of age. For the etiopathogenesis of KD, there is no agreement even as to whether KD is an infectious disease or an immune-mediated disease. The epidemiologic characteristics of KD, including the strict predilection of age in all ethnic groups and the gradually increased incidence after the KD emergence, suggest that KD is affected by the immune maturation in early childhood that may be determined by genetic factors, and KD is also affected by the changed environmental circumstances such as improved public hygiene.

We postulated that the pathogenesis of KD is a hyperimmune reaction in genetically susceptible children to the variants of normal flora, which are induced by the environmental factors. Using this hypothesis, we might partly explain the clinical and epidemiological characteristics of KD. We expect that this hypothesis may help to determine the causative agents for KD in the near future.

Immunoglobulin G has a role for systemic protein modulation in vivo: a new concept of protein homeostasis

The constant level of various proteins including albumin and cellular components in intravascular pool in vivo is strictly controlled by an unknown homeostatic mechanism, although there are fluctuations seen in pathologic conditions. Because the majority of the IgG in the serum is regarded as self-reactive natural autoantibodies, IgG may have a role to react with all proteins in vivo. It is hypothesized that like an immune system, a homeostatic mechanism for the protein pool also has a sensitive role to identify and memorize the extent and repertoire of both normal and pathogenic proteins on an individual basis, and IgG may be one of the major players in performing these functions. This hypothesis may explain the unresolved clinical observations as followed: (1) the marked increased IgG levels observed in self-limiting diseases presumed to come from immunological insults such as acute poststreptococcal glomerulonephritis and Kikuchi-Fujimoto disease, (2) an immediate reduction of all protein levels except immunoglobulins after intravenous immunoglobulin (IVIG) treatment in Kawasaki disease, (3) a unified explanation for the variety of immunomodulating effects exerted by IVIG, (4) the IgG-enzyme complexes observed in benign conditions such as macroamylasemia and hyperphosphatasemia, and (5) the marked decreased IgG level, which is correlated with the albumin level in minimal change nephrotic syndrome. IgG may be a 'watch-dog' for the disturbances of protein homeostasis in vivo. IgG may control the pathogenic proteins that appeared in disordered states, and it may help prevent the loss of proteins in case of nephrotic syndrome.

Effects of intravenous immunoglobulin and methylprednisolone on human umbilical vein endothelial cells in vitro

Endothelial cells (ECs) do more than just play a role in distinguishing blood and tissues. These cells are also influenced by various chemical mediators present in the blood and tissues. In addition, they produce diverse cytokines, chemokines, adhesion molecules, and growth factors. Therefore, ECs are actively involved in the inflammatory and immune response. We investigated the effects of intravenous immunoglobulin (IVIG) and methylprednisolone (MP) on activated human ECs, by examining the individual and combined effects of the drugs. Human umbilical vein ECs (HUVECs) obtained from the umbilical cords of healthy newborns were cultured. After the HUVECs were treated with interleukin (IL)-1beta, the effects of IVIG and/or MP on the activated HUVECs were assessed by cell proliferation, mRNA expression, and the production of vascular cell adhesion molecule (VCAM)-1, IL-1beta, and vascular EC growth factor (VEGF). IVIG and MP inhibited HUVEC proliferation. IVIG and MP significantly down regulated mRNA expression and the production of VCAM-1, IL-1beta, and VEGF. The combination of IVIG and MP generally showed a greater suppressive effect on mRNA expression and on the production of VCAM-1, IL-1beta, and VEGF. Our results suggest that some of the corticosteroid-sparing effects of IVIG observed in patients with severe asthma could be related to a decreased ability of ECs to proliferate, and to a down regulation of the expression of molecules involved in the onset and progression of airway inflammation.

Immunosuppressive effects of surgery assessed by flow cytometry in nonhuman primates after nephrectomy

Despite previous studies suggesting that surgery cause immune suppression, the underlying biologic mechanisms have not been studied using advanced immune function assays. Unilateral nephrectomy was performed in nonhuman primates. Blood was collected before surgery and at different time-points through 14 days after surgery. Lymphocyte proliferation (expression of proliferating cell nuclear antigen in cells in S/G(2)M-phase), production of intracellular cytokines [interleukin (IL)-2, interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha] and expression of surface-activation antigens (CD25, CD71) on T-lymphocytes were assessed in whole blood using flow cytometry. Results were compared with nonoperated control animals. The procedure caused a decrease of 25% in absolute lymphocyte count on postoperative day 3. Inhibition of lymphocyte proliferation was maximal on postoperative day 1 (55% normalized to preoperative values) and was detectable until postoperative day 7, when it was 25%. Expression of T-cell activation antigens was decreased during the first postoperative week with a maximum on postoperative day 1 for CD71 (29%) and on postoperative day 3 for CD25 (49%). Intracellular production of cytokines by T cells was decreased only on postoperative day 1 (50% for IL-2, 29% for IFN-gamma and 22% for TNF-alpha). Immune functions returned to presurgery values by day 14. A major surgical procedure severely inhibits lymphocyte proliferation and various T-cell functions up to 1 week postoperatively.