title: C5b-7 and C5b-8 precursors of the membrane attack complex (C5b-9) are effective killers of E. coli J5 during serum incubation.
abstract: The finding that C9-deficient sera (C9D) can kill serum sensitive strains of Gram-negative bacteria by us and other investigators, questions the role of C9 in the membrane attack complex as necessary for cell death. In these studies we have demonstrated that C5b-8 complexes generated on E. coli J5 during incubation in C9-depleted and C9-neutralized sera are effective in killing Gram-negative bacteria. In the same study, we extended our investigations to show that the deposition of C5b-7 complexes (from C8-deficient [C8D], C8 depleted and C8-neutralized sera) is also effective in killing Gram-negative bacteria. In all cases, these studies demonstrated that when E. coli J5 was incubated with C8D, C9D and pooled normal human serum [PNHS], deposited C5b-9 complexes from PNHS produced more killing than C5b-7 or C5b-8 complexes alone. These experiments clearly demonstrated that C5b-7 and C5b-8 complexes are bactericidal and that multimeric C9 within C5b-9 is not an absolute requirement for inner membrane damage and cell death of Gram-negative bacteria.
authors.affiliation: Department of Microbiology, Howard University College of Medicine, Washington, D.C., USA.
authors.forename: E F
authors.initials: EF
authors.lastname: Bloch
authors.forename: E M
authors.initials: EM
authors.lastname: Knight
authors.forename: T
authors.initials: T
authors.lastname: Carmon
authors.forename: S
authors.initials: S
authors.lastname: McDonald-Pinkett
authors.forename: J
authors.initials: J
authors.lastname: Carter
authors.forename: A
authors.initials: A
authors.lastname: Boomer
authors.forename: M
authors.initials: M
authors.lastname: Ogunfusika
authors.forename: M
authors.initials: M
authors.lastname: Petersen
authors.forename: B
authors.initials: B
authors.lastname: Famakin
authors.forename: J
authors.initials: J
authors.lastname: Aniagolu
authors.forename: J
authors.initials: J
authors.lastname: Walker
authors.forename: R
authors.initials: R
authors.lastname: Gant
authors.forename: C S
authors.initials: CS
authors.lastname: Walters
authors.forename: T A
authors.initials: TA
authors.lastname: Gaither
mesh_terms: D001770:Blood Bactericidal Activity; D015169:Colony Count, Microbial; D003182:Complement C5 / Q000276:immunology*; D003185:Complement C8 / Q000172:deficiency; D015938:Complement Membrane Attack Complex / Q000276:immunology*; D003165:Complement System Proteins / Q000276:immunology*; D004926:Escherichia coli / Q000276:immunology*; D006801:Humans; D066298:In Vitro Techniques; D009500:Neutralization Tests
chemical_list: D003182:Complement C5; D003185:Complement C8; D015938:Complement Membrane Attack Complex; C042295:complement C5b-8 complex; C037453:complement C5b-7 complex; D003165:Complement System Proteins