Figure 1. Detection of S. typhimurium by the innate immune system results in neutrophil recruitment. Complement, TLR5 and TLR4/MD2/CD14 detect conserved molecular patterns of S. typhimurium, including LPS and flagella. A pathogen-induced process detected by the host innate immune system is the deployment of T3SS-1, which is sensed through NLRC4. Signals generated by activation of complement, TLR5, TLR4/MD2/CD14 and NLRC4 cooperate in orchestrating neutrophil recruitment.