RT Journal Article SR Electronic(1) A1 Alhede, Morten A1 Bjarnsholt, Thomas A1 Jensen, Peter Ø. A1 Phipps, Richard Kerry A1 Moser, Claus A1 Christophersen, Lars A1 Christensen, Louise Dahl A1 van Gennip, Maria A1 Parsek, Matt A1 Høiby, Niels A1 Rasmussen, Thomas Bovbjerg A1 Givskov, MichaelYR 2009 T1 Pseudomonas aeruginosa recognizes and responds aggressively to the presence of polymorphonuclear leukocytes JF Microbiology, VO 155 IS 11 SP 3500 OP 3508 DO https://doi.org/10.1099/mic.0.031443-0 PB Microbiology Society, SN 1465-2080, AB Polymorphonuclear neutrophilic leukocytes (PMNs) play a central role in innate immunity, where they dominate the response to infections, in particular in the cystic fibrosis lung. PMNs are phagocytic cells that produce a wide range of antimicrobial agents aimed at killing invading bacteria. However, the opportunistic pathogen Pseudomonas aeruginosa can evade destruction by PMNs and thus cause persistent infections. In this study, we show that biofilm cells of P. aeruginosa recognize the presence of attracted PMNs and direct this information to their fellow bacteria through the quorum sensing (QS) signalling system. The bacteria respond to the presence of PMNs by upregulating synthesis of a number of QS-controlled virulence determinants including rhamnolipids, all of which are able to cripple and eliminate cells of the host defence. Our in vitro and in vivo analyses support a ‘launch a shield’ model by which rhamnolipids surround the biofilm bacteria and on contact eliminate incoming PMNs. Our data strengthen the view that cross-kingdom communication plays a key role in P. aeruginosa recognition and evasion of the host defence., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.031443-0