Abstract
ABSTRACT: Previous studies demonstrated that, compared with adult serum, neonatal serum contained a diminished concentration of complement component C9 and that supplemental C9 enhanced the capacity of neonatal serum to kill an isolate of Escherichia coli. Therefore, experiments were designed to determine the mechanisms by which supplemental C9 enhances the bactericidal capacity of neonatal serum and to determine whether supplemental C9 enhances the capacity of neonatal serum to kill several different pathogenic strains of E. coli. A radiobinding assay and immunogold electron microscopy using a monoclonal anti-C9 antibody revealed that, compared with 40% adult serum, neonatal serum deposited a diminished quantity of C9 onto E. coli O7w:K1:NM. Supplemental C9 (75 mg/L) significantly enhanced the quantity of C9 deposited by the neonatal serum. Treatment with 10 mM MgEGTA (a mixture of 100 mM MgCl2 and 100 mM EGTA that blocks activation of the classic complement pathway but leaves the alternative pathway intact) abolished the capacity of neonatal serum to deposit C9 and to kill the bacteria. Supplemental C9 enhanced the capacity of neonatal serum to kill eight different blood isolates of E. coli. Therefore, supplemental C9 enhanced the capacity of neonatal serum to kill E. coli by increasing the total quantity of C9 deposited via activation of the classic complement pathway. Neonatal serum contained sufficient quantities of classic pathway components, other than C9, to deposit the supplemental C9 onto E. coli and to enhance bacterial killing. The bactericidal activity of neonatal serum against multiple isolates of pathogenic E. coli was increased after C9 supplementation. We speculate that C9 deficiency may be one of the defects in antibacterial host defense that predisposes neonates to the acquisition of E. coli sepsis.
Similar content being viewed by others
Article PDF
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Lassiter, H., Wilson, J., Feldhoff, R. et al. Supplemental Complement Component C9 Enhances the Capacity of Neonatal Serum to Kill Multiple Isolates of Pathogenic Escherichia coli. Pediatr Res 35, 389–395 (1994). https://doi.org/10.1203/00006450-199404000-00002
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1203/00006450-199404000-00002
This article is cited by
-
Complement levels in patients with bloodstream infection due to Staphylococcus aureus or Gram-negative bacteria
European Journal of Clinical Microbiology & Infectious Diseases (2020)
-
The sensitivity ofEscherichia coli strains with K1 surface antigen and rods without this antigen to the bactericidal effect of serum
Folia Microbiologica (2004)