Inhibition of Cell Adhesion by Antibodies to Arg-Gly-Asp (RGD) in Normal Immunoglobulin for Therapeutic Use (Intravenous Immunoglobulin, IVIg)

Abstract

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 attachment site of a number of adhesive extracellular matrix proteins, including ligands for β1, β3, and β5 integrins. Anti-RGD antibodies were identified in IVIg by enzyme-linked immunosorbent assay and by using the BIAcore (BIAcore, Uppsala, Sweden) technology. The affinity of anti-RGD antibodies to a synthetic RGD-containing peptide and to fibronectin (Fn) was found to be in the micromolar range. F(ab′)2 fragments specific for RGD were purified from IVIg by affinity chromatography. Anti-RGD F(ab′)2 antibodies inhibited adenosine diphosphate induced IIb/β3 integrin-mediated platelet aggregation and the adhesion of activated 4β1 integrin-expressing B cells to Fn. Adhesion of unstimulated platelets to fibrinogen (Fg) involving both the γ-chain dodecapeptide sequence and the RGD sequence was inhibited by anti-RGD antibodies. In addition, adhesion of thrombin-stimulated platelets to von Willebrand factor or Fg was completely inhibited by affinity-purified anti-RGD antibodies. Our results suggest that the presence of natural IgG antibodies to the RGD motif may contribute to the immunomodulatory and anti-inflammatory effects of therapeutic preparations of normal IgG.

Kawasaki disease: Aetiopathogenesis and therapeutic utility of intravenous immunoglobulin

“…Many of the integrins share affinity towards the RGD recognition sequence (the Arg-Gly-Asp motif) in their extracel-lular matrix ligand and are able to discriminate between different RGD-containing proteins. We have shown that IVIG contains antibodies that bind to human RGD-containing integrin ligands [91]. The biological relevance of anti-RGD antibodies in IVIG was demonstrated by their ability to inhibit B-lymphocyte adhesion to fibronectin.…”

Clinical uses of intravenous immunoglobulin

“…IVIG has also been shown to reduce adhesion of T cells to extracellular matrix following activation by phytohaemagglutinin (PHA) or phorbol myristate acetate (PMA) [13] and contains antibodies to the Arg-Gly-Asp (RGD) motif, the attachment site for a number of adhesive extracellular matrix proteins and b 1, b 3 and b 5 integrins [14].…”

Serum IgM, IgG and IgA block by F(ab′)2‐dependent mechanism the binding of natural IgG autoantibodies from therapeutic immunoglobulin preparations to self‐antigens

“…The spectrum of self-antigens to which these antibodies bind, their fate after intravenous infusion and their biological activity remain a matter of controversy. We (14)(15)(16), as well as others (17), have previously suggested that natural IgG autoantibodies specific to lymphocyte surface molecules may be partially responsible for the beneficial immunomodulatory effects of IVIg in autoimmune patients.…”

“…It was cultured in the peritoneum of pristane-pretreated SCID mice (obtained from Iffa Credo, L'Arbresle, France) and the pure antibody was obtained from their ascitic fluid. F(ab¢) 2 fragments were prepared from the IVIg preparation and from the M061 monoclonal antibody as previously described (15).…”