Rapid killing of actinomycin D-treated tumor cells-cytotoxicity of cell-free monocyte supernatants

Laura Bersani, Francesco Colotta, Pietro Ghezzi, Alberto Mantovani

Research output: Contribution to journalArticlepeer-review


Human monocytes kill Actinomycin D-treated WEH1 164 sarcoma cells in a 6 h 51Cr release assay (drug dependent cellular cytotoxicity, DDCC). In the present study we have investigated and characterized the human monocyte production of a cytotoxic factor which mediates DDCC. Cell-free supernatants obtained culturing monocytes for 4-5 h kill Actinomycin D-treated WEHI 164 cells but not untreated tumor cells. A series of antiproteases inhibits the cytotoxic activity of cell-free monocyte supernatants, whereas scavengers of reactive oxygen intermediates were ineffective. The lytic activity was destroyed treating supernatants at 100°C for 5 min or by exposure to acid pH or to proteinase K, whereas it was unaffected by heating at 56°C for 30 min. Upon gel filtration on Sephacryl S200, cytolytic activity eluted in the 33,000 molecular weight range.

Original languageEnglish
Pages (from-to)351-355
Number of pages5
JournalImmunology Letters
Issue number5-6
Publication statusPublished - 1985


  • Actinomycin D
  • cytotoxicity
  • monocytes

ASJC Scopus subject areas

  • Immunology
  • Immunology and Allergy


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