Whole blood assay as a model for in vitro evaluation of inflammasome activation and subsequent caspase-mediated interleukin-1 beta release

PLoS One. 2019 Apr 8;14(4):e0214999. doi: 10.1371/journal.pone.0214999. eCollection 2019.


Processing of pro-interleukin (IL)-1β and IL-18 is regulated by multiprotein complexes, known as inflammasomes. Inflammasome activation results in generation of bioactive IL-1β and IL-18, which can exert potent pro-inflammatory effects. Our aim was to develop a whole blood-based assay to study the inflammasome in vitro and that also can be used as an assay in clinical studies. We show whole blood is a suitable milieu to study inflammasome activation in primary human monocytes. We demonstrated that unprocessed human blood cells can be stimulated to activate the inflammasome by the addition of adenosine 5'-triphosphate (ATP) within a narrow timeframe following lipopolysaccharide (LPS) priming. Stimulation with LPS resulted in IL-1β release; however, addition of ATP is necessary for "full-blown" inflammasome stimulation resulting in high IL-1β and IL-18 release. Intracellular cytokine staining demonstrated monocytes are the major producers of IL-1β in human whole blood cultures, and this was associated with activation of caspase-1/4/5, as detected by a fluorescently labelled caspase-1/4/5 probe. By applying caspase inhibitors, we show that both the canonical inflammasome pathway (via caspase-1) as well as the non-canonical inflammasome pathway (via caspases-4 and 5) can be studied using this whole blood-based model.

MeSH terms

  • Caspases / immunology*
  • Humans
  • Inflammasomes / immunology*
  • Inflammation / chemically induced
  • Inflammation / immunology
  • Inflammation / pathology
  • Interleukin-18 / immunology
  • Interleukin-1beta / immunology*
  • Lipopolysaccharides / toxicity
  • Models, Immunological*
  • Monocytes / immunology*
  • Monocytes / pathology
  • Signal Transduction / drug effects
  • Signal Transduction / immunology*


  • IL1B protein, human
  • Inflammasomes
  • Interleukin-18
  • Interleukin-1beta
  • Lipopolysaccharides
  • Caspases

Grant support

Good Biomarker Sciences provided support in the form of salaries for authors [TATT, KL, KEM, DT], but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the 'author contributions' section.