Importance of antibody and complement for oxidative burst and killing of invasive nontyphoidal Salmonella by blood cells in Africans

Research output: Contribution to journalArticle

Authors

  • EN Gondwe
  • ME Molyneux
  • SM Graham
  • P Mastroeni

Colleges, School and Institutes

Abstract

Bacteremia caused by nontyphoidal strains of Salmonella is endemic among African children. Case-fatality rates are high and antibiotic resistance increasing, but no vaccine is currently available. T cells are important for clearance of Salmonella infection within macrophages, but in Africa, invasive Salmonella disease usually manifests in the blood and affects children between 4 months and 2 y of age, when anti-Salmonella antibody is absent. We have previously found a role for complement-fixing bactericidal antibody in protecting these children. Here we show that opsonic activity of antibody and complement is required for oxidative burst and killing of Salmonella by blood cells in Africans. Induction of neutrophil oxidative burst correlated with anti-Salmonella IgG and IgM titers and C3 deposition on bacteria and was significantly lower in African children younger than 2 y compared with older children. Preopsonizing Salmonella with immune serum overcame this deficit, indicating a requirement for antibody and/or complement. Using different opsonization procedures, both antibody and complement were found to be necessary for optimal oxidative burst, phagocytosis and killing of nontyphoidal Salmonella by peripheral blood cells in Africans. Although most strains of African nontyphoidal Salmonella can be killed with antibody and complement alone, phagocytes in the presence of specific antibody and complement can kill strains resistant to killing by immune serum. These findings increase the likelihood that an antibody-inducing vaccine will protect against invasive nontyphoidal Salmonella disease in African children.

Details

Original languageEnglish
Pages (from-to)3070-3075
Number of pages6
JournalNational Academy of Sciences. Proceedings
Volume107
Issue number7
Publication statusPublished - 1 Feb 2010

Keywords

  • vaccines, opsonic activity, bactericidal antibody, immunity, bacteremia