title: Anti-CD40 antibodies in antiphospholipid syndrome and systemic lupus erythematosus.
abstract: Anti-beta2glycoprotein I (anti-beta2GPI) antibodies constitute the main autoantibody specificity in the sera of patients with antiphospholipid syndrome (APS). There is evidence that anti-beta2GPI antibodies induce the precoagulant activity of the endothelium by cross-linking the beta2 glycoprotein I (beta2GPI) on the cell surface. Since beta2GPI lacks intracellular domains, homology with other molecules such as CD40 that could initiate signaling, was extensively searched. A 86% homology between the amino acid position 239-245 of the CD40 and 7-13 of the beta2glycoprotein was found. The CD40 peptide corresponding to amino acids 239-245 of the CD40 molecule was synthesized and coupled to a multiple antigenic peptide carrier. Antibodies to CD40 peptide were found in 61.5% APS patients (n = 39), in 72.7% of systemic lupus erythematosus (SLE) positive for anti-beta2GPI antibodies (n = 11) and 31.6% of SLE negative for anti-beta2GPI antibodies (n = 19), but not in rheumatoid arthritis patients (n = 28) or controls (n = 36). Antibodies to CD40 peptide were associated with arterial thrombosis and/or brain microinfarcts. Affinity purified anti-CD40 peptide antibodies as well as affinity purified anti-beta2GPI antibodies recognized both, the beta2GPI and the CD40 peptide. The specificity of this recognition was confirmed with homologous and heterologous inhibition experiments. Confocal microscopy experiments demonstrated this cross-recognition of CD40 and beta2GPI molecules, by the purified anti-CD40 peptide antibodies, at the protein level. Thus, antibodies reacting with the beta2GPI can react and potentially activate different cells which express CD40 molecules at their surface.
authors.affiliation: Department of Pathophysiology, Medical School, National University of Athens, 75, Mikras Asias St 11527, Athens, Greece. pvlah@med.uoa.gr
authors.forename: Panayiotis G
authors.initials: PG
authors.lastname: Vlachoyiannopoulos
authors.forename: Clio P
authors.initials: CP
authors.lastname: Mavragani
authors.forename: Efi
authors.initials: E
authors.lastname: Bourazopoulou
authors.forename: Anthi V
authors.initials: AV
authors.lastname: Balitsari
authors.forename: John G
authors.initials: JG
authors.lastname: Routsias
mesh_terms: D000328:Adult; D000906:Antibodies / Q000737:chemistry*; D017152:Antibodies, Antiphospholipid / Q000276:immunology; D000911:Antibodies, Monoclonal; D016736:Antiphospholipid Syndrome / Q000097:blood* / Q000276:immunology*; D001323:Autoantibodies / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology; D019013:CD40 Antigens / Q000096:biosynthesis / Q000276:immunology*; D002461:Cell Line, Transformed; D002462:Cell Membrane / Q000378:metabolism; D002845:Chromatography; D002852:Chromatography, Ion Exchange; D004730:Endothelium, Vascular / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D016650:Fluorescein-5-isothiocyanate / Q000494:pharmacology; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000097:blood* / Q000276:immunology*; D018613:Microscopy, Confocal; D008875:Middle Aged; D008954:Models, Biological; D010455:Peptides / Q000737:chemistry; D017434:Protein Structure, Tertiary; D012680:Sensitivity and Specificity; D015398:Signal Transduction
chemical_list: D000906:Antibodies; D017152:Antibodies, Antiphospholipid; D000911:Antibodies, Monoclonal; D001323:Autoantibodies; D019013:CD40 Antigens; D010455:Peptides; D016650:Fluorescein-5-isothiocyanate