Cytolethal distending toxin of Haemophilus ducreyi induces apoptotic death of Jurkat T cells

Valentina Gelfanova, Eric J. Hansen, Stanley M. Spinola

Research output: Contribution to journalArticlepeer-review

56 Scopus citations


The immune response to Haemophilus ducreyi is mediated in part by T cells infiltrating the site of infection. In this study, we show that H. ducreyi antigen preparations inhibited the proliferation of peripheral blood mononuclear cells and primary human T-cell lines. H. ducreyi also inhibited Jurkat T-cell proliferation and induced apoptosis of Jurkat T cells, confirmed through the detection of DNA degradation and membrane unpacking. The cytotoxic product(s) was present in cell-free culture supernatant and whole-cell preparations of H. ducreyi and was heat labile. H. ducreyi produces two known heat-labile toxins, a hemolysin and a cytolethal distending toxin (CDT). Whole cells and supernatants prepared from a hemolysin-deficient mutant had the same inhibitory and apoptotic effects on Jurkat T cells as did its isogenic parent. Preparations made from an H. ducreyi cdtC mutant were less toxic and induced less apoptosis than the parent. The toxic activity of the cdtC mutant was restored by complementation in trans. CdtC-neutralizing antibodies also inhibited H. ducreyi induced toxicity and apoptosis. The data suggest that CDT may interfere with T-cell responses to H. ducreyi by induction of apoptosis.

Original languageEnglish (US)
Pages (from-to)6394-6402
Number of pages9
JournalInfection and immunity
Issue number12
StatePublished - Dec 1999

ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Immunology
  • Infectious Diseases


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