It inhibited the induction of IL-6, IL-8 and TNF-α in human monocytes by: (i) ultrapure Shigella LPS and wild-type S. flexneri (M90T strain at a multiplicity of infection of 10; Fig 4D); (ii) ultrapure LPS-gtrA and the genetically engineered strain gtrA (Fig 4E); (iii) ultrapure LPS-waaL and the genetically engineered strain waaL (Fig 4F). Here, IL6 is linked to infection.