title: Complement-mediated bactericidal activity of human antibodies to poly alpha 2-->8 N-acetylneuraminic acid, the capsular polysaccharide of Neisseria meningitidis serogroup B.
abstract: Serum antibodies to Neisseria meningitidis group B (MenB) polysaccharide are reported not to elicit bacteriolysis in the presence of human complement. To reexamine this question, we evaluated the ability of two human IgM anti-MenB polysaccharide monoclonal antibodies (MAbs) and seven human MenB polysaccharide-reactive human IgM paraproteins to elicit bacteriolysis. In the presence of human complement, both MAbs and five of the seven paraproteins were bactericidal at antibody concentrations of 0.25-9.6 micrograms/mL (50% killing). Activity of the respective antibodies was enhanced 200- to > 10,000-fold when rabbit complement was used instead of human complement. With rabbit complement, the bactericidal activity of human IgM polyclonal antibody or MAb to Haemophilus influenzae type b (Hib) polysaccharide but not human IgG polyclonal antibody or MAb to Hib polysaccharide was similarly augmented. Thus, for both MenB and Hib, IgM antipolysaccharide antibodies elicit complement-mediated bactericidal activity in the presence of human complement, and the use of rabbit complement yields spuriously high activity.
authors.affiliation: Children's Hospital Oakland Research Institute, CA 94609, USA.
authors.forename: R E
authors.initials: RE
authors.lastname: Mandrell
authors.forename: F H
authors.initials: FH
authors.lastname: Azmi
authors.forename: D M
authors.initials: DM
authors.lastname: Granoff
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood / Q000276:immunology*; D000911:Antibodies, Monoclonal; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology; D001770:Blood Bactericidal Activity / Q000276:immunology*; D003165:Complement System Proteins / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000145:classification / Q000276:immunology; D007075:Immunoglobulin M / Q000097:blood / Q000276:immunology; D051379:Mice / Q000276:immunology; D009345:Neisseria meningitidis / Q000145:classification / Q000276:immunology*; D010266:Paraproteins / Q000276:immunology*; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D011817:Rabbits; D012703:Serotyping; D012794:Sialic Acids / Q000276:immunology*; D013045:Species Specificity
chemical_list: D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D001425:Bacterial Outer Membrane Proteins; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D010266:Paraproteins; D011135:Polysaccharides, Bacterial; D012794:Sialic Acids; C021319:polysialic acid; D003165:Complement System Proteins