Caspases -2, -3, -6, and -9, but not caspase-1, are activated in sepsis-induced thymocyte apoptosis

Kevin W. Tinsley, Shan L. Cheng, Timothy G. Buchman, Kathleen C. Chang, Jia Ji Hui, Paul E. Swanson, Irene E. Karl, Richard S. Hotchkiss*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


Sepsis induces extensive lymphocyte cell death that may contribute to immune depression and morbidity/mortality in the disorder. bcl-2 is a member of a new class of oncogenes that prevents cell death from an array of noxious stimuli. Transgenic mice that overexpress BCL-2 in T lymphocytes are resistant to sepsis-induced T cell apoptosis, and mortality was decreased in sepsis. The purpose of this study was to identify key initiator and executioner "caspases" involved in sepsis-induced lymphocyte apoptosis and to determine if BCL-2 acts prior to caspase activation. Thymi were removed 5-22 h post-cecal ligation and puncture (CLP) or sham surgery. Apoptosis was evaluated in thymocytes by annexin-V FITC labeling and flow cytometry. Caspase-1 activity was determined by western blot analysis of the procaspase protein and p20 subunit of the activated caspase; activities of caspases -2, -6, and -9 were determined by colorimetric assays using specific substrates conjugated to a color reporter molecule. Caspase-3 activity was determined both by western blot and by a fluorogenic assay in which a fluorescent compound was generated. Thymocytes from CLP mice had markedly increased apoptosis and activation of caspases -2, -3, -6, and -9 in comparison with thymocytes of sham-operated mice. Caspase-1 was not activated. BCL-2 prevented sepsis-induced thymocyte apoptosis and inhibited activation of all caspases. We conclude that sepsis causes activation of multiple caspases and that BCL-2 acts upstream as an inhibitor of caspase activation. The pattern of caspase activation suggests a mitochondrial mediated pathway.

Original languageEnglish
Pages (from-to)1-7
Number of pages7
Issue number1
StatePublished - Jan 2000
Externally publishedYes


  • BCL-2
  • CLP
  • Endotoxin
  • Lymphocytes
  • Programmed cell death


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