Fig. 4.

L. monocytogenes induces a cytokine cascade early in infection. a Bacteria are taken up by phagocytic cells including macrophages (Mϕ) and neutrophils. Cell wall components activate macrophages to produce b IL-12 and TNF-α that activate NK cells, and c IL-1 that activates neutrophils. Activated NK cells produce d IFN-γ that acts on macrophages to up-regulate antigen-processing machinery and increase the further production of IL-12, and e it drives the maturation of Th0 cells to Th1 cells. Reproduced with permission of the authors and publishers, from Gunn et al. [4]