title: In vitro cleavage of serum complement protein C3: a comparison between patients with adult periodontitis and periodontally healthy persons.
abstract: This study tested the hypothesis that in vitro cleavage of C3 could be triggered with similar case in serum samples from patients with adult periodontitis (n = 26) as in samples from periodontally healthy subjects (n = 13). A lipoteichoic acid, a lipopolysaccharide and an aggregated IgG served as activators of complement. On the average, the periodontitis group generated significantly (p < 0.01) more C3d activation fragments than did the healthy group, as judged from rocket immunoelectrophoresis measurements. Cleavage of C4 and factor B were then assayed through immunoblotting, without prior purification of the sera. C4c fragments were seen in all activated samples, the healthy group causing significantly (p < 0.05) more C4 conversion than did the periodontitis group. Cleavage of factor B, taken as a measure of soluble amplification convertase formation, was about equal between the groups. We inferred therefore that the 2 groups produced comparable amounts of C3b. The results suggested, however, that periodontitis sera favour breakdown of the opsonin C3b, most likely by activating the regulatory proteins factor H and I. Lipoteichoic acid, causing moderate depletion of C4 and factor B, produced significantly (p < 0.01) more C3d fragments than the other two activators examined. It may be that complement activation is down-regulated in periodontitis sera, perhaps at the expense of adequate local opsonic function.
authors.affiliation: Department of Periodontology, Dental Faculty University of Oslo, Norway.
authors.forename: K
authors.initials: K
authors.lastname: Monefeldt
authors.forename: K
authors.initials: K
authors.lastname: Helgeland
authors.forename: T
authors.initials: T
authors.lastname: Tollefsen
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001797:Blood Protein Electrophoresis / Q000379:methods; D015153:Blotting, Western; D016022:Case-Control Studies; D003167:Complement Activation; D015933:Complement C3d / Q000032:analysis*; D015536:Down-Regulation; D005260:Female; D006801:Humans; D007123:Immunoelectrophoresis, Two-Dimensional; D007074:Immunoglobulin G / Q000276:immunology; D008070:Lipopolysaccharides / Q000276:immunology; D008297:Male; D010518:Periodontitis / Q000097:blood*; D012044:Regression Analysis; D013682:Teichoic Acids / Q000276:immunology
chemical_list: D007074:Immunoglobulin G; D008070:Lipopolysaccharides; D013682:Teichoic Acids; C009900:lipoteichoic acid; D015933:Complement C3d