Live Salmonella enterica serovar Typhimurium (S. Typhimurium) elicit dendritic cell responses that differ from those induced by killed S. Typhimurium

The immune response of bovine monocytes-derived dendritic cells (DC) exposed to either live or killed Salmonella enterica serovar Typhimurium was compared. Both live and killed bacteria induced changes in morphology with distinctive formation of processes and up-regulation of the ability of DC to stimulate allogeneic T-cell proliferation. Also, both live and killed bacteria up-regulated the expression of MHC-I, MHC-II and CD80. However, live bacteria induced greater up-regulation of the expression of CD40 and CD86 than killed bacteria. Live bacteria also induced greater up-regulation of transcription for IL-6, IL-12 and GM-CSF than killed bacteria as measured by quantitative RT-PCR. These data suggest that blood-monocyte-derived DC may follow distinct maturation pathways following exposure to live or killed bacteria. These differences are likely to have consequences for the priming of the adaptive immune responses.