Purity >98%. Quorum sensing is a regulatory system used by bacteria for controlling gene expression in response to increasing cell density. A promising field of study involves controlling bacterial infections by quenching their quorum sensing systems. The expression of specific target genes, such as transcriptional regulators belonging to the LuxIR family of proteins, is coordinated by synthesis of diffusible acylhomoserine lactone (AHL) molecules. N-3-oxo-dodecanoyl-L-homoserine lactone (3-oxo-C12-HSL) is one of the AHLs frequently identified in extracts of respiratory secretions from cystic fibrosis patients infected with P. aeruginosa and/or strains of the B. cepacia complex. 3-oxo-C12-HSL activates the transcription factors NF-?B and AP-2 to induce interleukin-8 production in human lung fibroblasts and epithelial cells, possibly contributing to the neutrophil infiltration and inflammation found in P. aeruginosa infections.