title: Purification and characterization of RHP (factor H) and study of its interactions with the first component of complement.
abstract: RHP has been purified from the plasma of both normal individuals and patients with rheumatoid arthritis (RA). RHP from both these sources was shown to be identical with Factor H by reaction with antisera and N-terminal amino acid sequence analysis. Factor H, from both normal and RA sera, inhibited the solubilization of immune precipitates but did not affect prevention of immune precipitation. Factor H was shown to inhibit the haemolytic activity of fluid-phase C1, but unlike C1-inhibitor, it had little effect on C1 bound to EA (EAC1). Factor H was shown to complex with intact C1, to isolated C1q and to the C1r:C1s tetramer. However, binding of factor H to C1 did not dissociate the C1 macromolecule. A C1-Factor H complex was detected in the serum and plasma from normal individuals and patients with systemic lupus erythematosus and RA. Serum levels of this complex were reduced, by EDTA-treatment of serum and by activation of complement by the classical pathway.
authors.affiliation: Department of Pathology, University of Glasgow, Western Infirmary, U.K.
authors.forename: E R
authors.initials: ER
authors.lastname: Holme
authors.forename: M
authors.initials: M
authors.lastname: Qi
authors.forename: A E
authors.initials: AE
authors.lastname: Ahmed
authors.forename: J
authors.initials: J
authors.lastname: Veitch
authors.forename: G
authors.initials: G
authors.lastname: Auda
authors.forename: K
authors.initials: K
authors.lastname: Whaley
mesh_terms: D001172:Arthritis, Rheumatoid / Q000097:blood*; D003172:Complement C1 / Q000502:physiology*; D003174:Complement C1 Inactivator Proteins / Q000494:pharmacology; D003180:Complement C3b Inactivator Proteins / Q000302:isolation & purification / Q000502:physiology*; D017242:Complement Factor H; D006801:Humans; D046911:Macromolecular Substances; D008970:Molecular Weight; D011485:Protein Binding
chemical_list: C493495:CFH protein, human; D003172:Complement C1; D003174:Complement C1 Inactivator Proteins; D003180:Complement C3b Inactivator Proteins; D046911:Macromolecular Substances; D017242:Complement Factor H