This method is based on HEK293 cells specifically engineered to selectively respond to IL-1 beta, named HEK-Blue IL-1 beta cells. 

HEK-Blue™ IL-1β cells provide a convenient read-out to determine the amount of IL-1β secreted by THP-1 cells following stimulation by NLRP3 inflammasome inducers.

HEK-Blue™ IL-1β cells feature the SEAP (secreted embryonic alkaline phosphotase) reporter gene under the control of an NF-κB-inducible promoter. They naturally express the IL-1β receptor (IL-1R), and all the proteins involved in the MyD88-dependent IL-1R signaling pathway that leads to NF-kB activation. Thus upon IL-1β binding to IL-1R, a signaling cascade is initiated triggering NF-kB activation and the subsequent production of SEAP. Detection of SEAP in the supernatant of HEK-Blue™ IL-1β cells can be readily assessed using QUANTI-Blue™, a SEAP detection medium. QUANTI-Blue™ turns blue in the presence of SEAP which can be easily quantified using a spectrophotometer.

HEK-Blue™ IL-1β cells are resistant to the selective antibiotics Zeocin™ and Hygromycin B. 

HEK-Blue™ IL-1β cells are useful to monitor IL-1β in inflammasome activation studies.
THP-1 human monocytic cells represent the most commonly used model cell line for the study of inflammasome activation. To become susceptible to inflammasome inducers, these cells must be induced by stimuli commonly used for induction in model systems, such as lipopolysaccharide (LPS) and phorbol 12-myristate acetate (PMA) [1, 2].
Stimulation by LPS or differentiation with PMA induces the production of pro-IL-1β, the immature form of IL-1β. Subsequent stimulation with inflammasome inducers, such as ATP and alum crystals, leads to caspase-1 activation and IL-1β maturation and secretion.
Stimulation of HEK-Blue™ IL-1β cells with supernatants of THP-1 cells treated with LPS or PMA and stimulated with inflammasome inducers triggers the production of SEAP that correlates with the presence of IL-1β in the supernatants (see THP-1/HEK-Blue™ IL-1β Assay). Coincubation with a monoclonal anti-IL-1β antibody blocks the response. 

1- Production of IL-1β by THP-1 cells: Typically, THP-1 cells are pretreated with phorbol 12-myristate acetate (PMA) to become more susceptible to inflammasome activators, then are primed with lipopolysaccharide (LPS). These treatments induce the production of pro-IL-1β, the immature form of IL-1β.
Subsequent stimulation with inflammasome inducers, such as crystals or ATP, leads to NRLP3 and caspase-1 activation resulting in IL-1β maturation and secretion.

2- Detection of IL-1β by HEK-Blue™ IL-1β cells: IL-1β-containing THP-1 supernatants are added to HEK-Blue™ IL-1β cells leading to NF-κB activation and the subsequent production of SEAP. The presence of SEAP in HEK-Blue™ IL-1β supernatants is assessed using QUANTI-Blue™, a SEAP detection medium.