Tchavdar L. Vassilev

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Intravenous immunoglobulin (IVIg) is increasingly used for the treatment of autoimmune diseases and the prevention of infections and of graft versus host reactions in recipients of allogeneic bone marrow transplants. The immunomodulatory effects of IVIg are largely dependent on their ability to interact with membrane molecules of lymphocytes. We report here(More)
IVIg are increasingly used for the treatment of autoimmune diseases. In the present study, we show that IVIg contain antibodies directed against CD5, a cell surface molecule of T cells which is also a marker of the autoantibody-producing CD20+ ('B-1') subset of B lymphocytes. Antibodies to the CD5 molecule were demonstrated in IVIg by the ability of(More)
Polyspecific antibodies represent a first line of defense against infection and regulate inflammation, properties hypothesized to rely on their ability to interact with multiple antigens. We demonstrated that IgG exposure to pro-oxidative ferrous ions or to reactive oxygen species enhances paratope flexibility and hydrophobicity, leading to expansion of the(More)
Normal human serum contains IgM antibodies that regulate the natural autoantibody activity of IgG in autologous serum. In the present study, we show that pooled normal human IgM (IVIgM) purified from plasma of more than 2,500 healthy donors and processed in a similar fashion to that of therapeutic preparations of pooled normal human IgG (IVIg) suppresses(More)
Serum IgM has been shown to participate in the control of IgG autoreactivity in healthy subjects. We have recently shown that an immunoglobulin preparation of pooled normal human IgM (IVIgM) contains anti-idiotypic antibodies against disease-associated IgG autoantibodies in autoimmune patients and protects rats from experimental autoimmunity. The aim of the(More)
Targeting autoreactive B lymphocytes at any stage of their differentiation could yield viable therapeutic strategies for treating autoimmunity. All currently used drugs, including the most recently introduced biological agents, lack target specificity. Selective silencing of double-stranded DNA-specific B cells in animals with spontaneous lupus has been(More)
Intravenous immunoglobulin (IVIg) therapy is associated with a broad range of immunomodulatory activities. Several of the postulated mechanisms of IVIg action relate to the presence of antibodies to molecules relevant for regulation of the immune response. This article reports that IVIg contains antibodies to the Arg-Gly-Asp (RGD) sequence, and the(More)
Reactive oxygen species (ROS) released from activated phagocytes are involved in the innate immune defense against pathogens. However, when released in excess and when the antioxidant systems are impaired, ROS may induce cellular and tissue damage and dissociation of iron ions or iron containing compounds (heme) from protein-bound state. Free iron ions and(More)
Various pathological processes are accompanied by release of high amounts of free heme into the circulation. We demonstrated by kinetic, thermodynamic, and spectroscopic analyses that antibodies have an intrinsic ability to bind heme. This binding resulted in a decrease in the conformational freedom of the antibody paratopes and in a change in the nature of(More)
An Ab molecule or a BCR that is able to bind multiple structurally unrelated Ags is defined as polyreactive. Polyreactive Abs and BCRs constitute an important part of immune repertoires under physiological conditions and may play essential roles in immune defense and in the maintenance of immune homeostasis. In this review, we integrate and discuss(More)