Biological defense mechanisms. The production by leukocytes of superoxide, a potential bactericidal agent

J Clin Invest. 1973 Mar;52(3):741-4. doi: 10.1172/JCI107236.


As a highly reactive substance produced in biological systems by the one-electron reduction of oxygen, superoxide (O(2) (-)) seemed a likely candidate as a bactericidal agent in leukocytes. The reduction of cytochrome c, a process in which O(2) (-) may serve as an electron donor, was found to occur when the cytochrome was incubated with leukocytes. O(2) (-) was identified as the agent responsible for the leukocyte-mediated reduction of cytochrome c by the demonstration that the reaction was abolished by superoxide dismutase, an enzyme that destroys O(2) (-), but not by boiled dismutase, albumin, or catalase. Leukocyte O(2) (-) production doubled in the presence of latex particles. The average rate of formation of O(2) (-) in the presence of these particles was 1.03 nmol/10(7) cells per 15 min. This rate, however, is only a lower limit of the true rate of O(2) (-) production, since any O(2) (-) which reacted with constituents other than cytochrome c would have gone undetected. Thus. O(2) (-) is made by leukocytes under circumstances which suggest that it may be involved in bacterial killing.

MeSH terms

  • Cytochrome c Group / metabolism
  • Humans
  • Latex / pharmacology
  • Leukocytes / metabolism*
  • Microspheres
  • Oxidation-Reduction
  • Oxygen Consumption
  • Oxygen*
  • Superoxide Dismutase / pharmacology


  • Cytochrome c Group
  • Latex
  • Superoxide Dismutase
  • Oxygen