TNF and infection: Endotoxin-free PAMAM-DG inhibited the induction of IL-6, IL-8 and TNF-α in human monocytes by: (i) ultrapure Shigella LPS and by wild type S. flexneri (M90T strain at a multiplicity of infection of 10; Fig 1D); (ii) ultrapure LPS-gtrA and the genetically engineered strain gtrA (Fig 1E); (iii) ultrapure LPS-waaL and the genetically engineered strain waaL (Fig 1F).