Cellular titration of apoptosis with steady state concentrations of H(2)O(2): submicromolar levels of H(2)O(2) induce apoptosis through Fenton chemistry independent of the cellular thiol state

Free Radic Biol Med. 2001 May 1;30(9):1008-18. doi: 10.1016/s0891-5849(01)00493-2.


Apoptosis was studied under conditions that mimic the steady state of H(2)O(2) in vivo. This is at variance with previous studies involving a bolus addition of H(2)O(2), a procedure that disrupts the cellular homeostasis. The results allowed us to define three phases for H(2)O(2)-induced apoptosis in Jurkat T-cells with reference to cytosolic steady state concentrations of H(2)O(2) [(H(2)O(2))(ss)]: (H(2)O(2))(ss) values below 0.7 microM elicited no effects; (H(2)O(2))(ss) approximately 0.7-3 microM induced apoptosis; and (H(2)O(2))(ss) > 3 microM yielded no additional apoptosis and a gradual shift towards necrosis as the mode of cell death were observed. H(2)O(2)-induced apoptosis was not affected by either BCNU, an inhibitor of glutathione reductase, or diamide, a compound that reacts both with low-molecular weight and protein thiols, or selenols. Glutathione depletion, accomplished by incubating cells either with buthionine sulfoximine or in cystine-free medium, rendered cells more sensitive to H(2)O(2)-induced apoptosis, but did not change the threshold and saturating concentrations of H(2)O(2) that induced apoptosis. Two unrelated metal chelators, desferrioxamine and dipyridyl, strongly protected against H(2)O(2)-induced apoptosis. It may be concluded that, under conditions of H(2)O(2) delivery that mimic in vivo situations, the oxidative event that triggers the induction of apoptosis by H(2)O(2) is a Fenton-type reaction and is independent of the thiol or selenium states of the cell.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 2,2'-Dipyridyl / pharmacology
  • Apoptosis / drug effects
  • Apoptosis / physiology*
  • Carmustine / pharmacology
  • Chelating Agents / pharmacology
  • Deferoxamine / pharmacology
  • Diamide / pharmacology
  • Enzyme Inhibitors / pharmacology
  • Free Radicals / metabolism
  • Glutathione / metabolism
  • Glutathione Reductase / antagonists & inhibitors
  • Humans
  • Hydrogen Peroxide / metabolism*
  • Jurkat Cells
  • Necrosis
  • Oxidation-Reduction
  • Selenium / metabolism
  • Sulfhydryl Compounds / metabolism*


  • Chelating Agents
  • Enzyme Inhibitors
  • Free Radicals
  • Sulfhydryl Compounds
  • Diamide
  • 2,2'-Dipyridyl
  • Hydrogen Peroxide
  • Glutathione Reductase
  • Glutathione
  • Selenium
  • Deferoxamine
  • Carmustine