title: Enhancement of complement-mediated lysis by a peptide derived from SCR 13 of complement factor H.
abstract: Complement factor H (fH) is an important regulator of complement activation. It contributes to protection of cells against homologous complement attack. In this study we tested the effect of fH-depletion of normal human serum (NHS) on lysis of antibody-coated sheep and human erythrocytes (EshA and EhuA). In the absence of fH, lysis of sensitised Esh and Ehu was clearly increased. Addition of fH to fH-depleted serum re-established protection of cells against complement similar to that seen with NHS. A fH-derived peptide (pepAred), covering the N-terminal half of SCR 13 in fH, was able to enhance complement-mediated lysis of EhuA significantly. However, the oxidised form of this peptide (pepAox) had no effect. Biotinylated pepAred, but not pepAox, was able to directly bind to cells. Additionally, pepAred competed with direct fH-cell interaction which was observable only after treatment of purified fH with mercaptoethanol. Only pepAred increased the amount of C3 fragments and reduced levels of fH detectable on cells as shown by FACS analysis and radio-immuno assay. Furthermore, fH and factor I (fI)-mediated cleavage of agarose bound C3b into iC3b was decreased in the presence of pepAred. These data indicate that a fH-derived peptide can enhance complement-mediated lysis. We will continue to investigate whether the use of a fH peptide can be exploited for therapeutical purposes.
authors.affiliation: Institute of Hygiene and Social Medicine, Innsbruck, Austria. heribert.stoiber@uibk.ac.at
authors.forename: H
authors.initials: H
authors.lastname: Stoiber
authors.forename: C
authors.initials: C
authors.lastname: Ammann
authors.forename: M
authors.initials: M
authors.lastname: Spruth
authors.forename: B
authors.initials: B
authors.lastname: Müllauer
authors.forename: A
authors.initials: A
authors.lastname: Eberhart
authors.forename: C L
authors.initials: CL
authors.lastname: Harris
authors.forename: C G
authors.initials: CG
authors.lastname: Huber
authors.forename: R
authors.initials: R
authors.lastname: Longhi
authors.forename: B
authors.initials: B
authors.lastname: Falkensammer
authors.forename: R
authors.initials: R
authors.lastname: Würzner
authors.forename: M P
authors.initials: MP
authors.lastname: Dierich
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D003167:Complement Activation; D017242:Complement Factor H / Q000276:immunology* / Q000302:isolation & purification; D016384:Consensus Sequence; D004912:Erythrocytes / Q000276:immunology; D006461:Hemolysis / Q000276:immunology; D006801:Humans; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000276:immunology* / Q000302:isolation & purification; D020449:Repetitive Sequences, Amino Acid; D012756:Sheep
chemical_list: C493495:CFH protein, human; D010446:Peptide Fragments; D017242:Complement Factor H