title: Human autoantibodies against Clq: lack of cross reactivity with the collectins mannan-binding protein, lung surfactant protein A and bovine conglutinin.
abstract: The collectins, a group of humoral C-type lectins, have globular and collagen-like regions and share structural features with the complement protein C1q. The question was asked if autoantibodies to the collagen-like region of C1q (anti-C1qCLR) might cross-react with collectins, such as mannan-binding protein (MBP), lung surfactant protein A (SP-A) and bovine conglutinin (BK). Anti-C1qCLR antibodies of the systemic lupus erythematosus (SLE) type and anti-C1qCLR antibodies of the hypocomplementemic urticarial vasculitis syndrome (HUVS) type were investigated. Cross-absorption and elution experiments combined with antibody detection by enzyme-linked immunosorbent assay (ELISA) and immunoblot analysis gave no evidence of cross-reactive anti-C1qCLR antibodies. However, one serum with HUVS type anti-C1qCLR antibodies contained anti-MBP antibodies that were cross-reactive with SP-A. Judging from results of ELISA inhibition experiments and immunoblot analysis, four SLE sera contained antibodies to native BK, while two sera with HUVS type anti-C1qCLR antibodies contained antibodies to epitopes of denatured BK. This might imply that autoimmunity to collagen-like structures is not restricted to C1qCLR in HUVS and HUVS/SLE overlap syndromes.
authors.affiliation: Department of Medical Microbiology, Clinical Immunology Section, Lund University, Sweden.
authors.forename: U
authors.initials: U
authors.lastname: Mårtensson
authors.forename: S
authors.initials: S
authors.lastname: Thiel
authors.forename: J C
authors.initials: JC
authors.lastname: Jensenius
authors.forename: A G
authors.initials: AG
authors.lastname: Sjöholm
mesh_terms: D000818:Animals; D001323:Autoantibodies / Q000097:blood / Q000737:chemistry* / Q000187:drug effects; D001666:Binding Sites, Antibody; D001667:Binding, Competitive / Q000276:immunology; D002352:Carrier Proteins / Q000276:immunology*; D002417:Cattle; D037222:Collectins; D015922:Complement C1q / Q000276:immunology*; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D006023:Glycoproteins / Q000276:immunology; D006801:Humans; D015151:Immunoblotting; D037102:Lectins / Q000276:immunology; D008351:Mannans / Q000276:immunology; D011510:Proteolipids / Q000276:immunology*; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000276:immunology*; D012712:Serum Globulins / Q000276:immunology* / Q000494:pharmacology
chemical_list: D001323:Autoantibodies; D002352:Carrier Proteins; D037222:Collectins; D006023:Glycoproteins; D037102:Lectins; D008351:Mannans; D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; D012712:Serum Globulins; C024014:conglutinin; D015922:Complement C1q