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. Author manuscript; available in PMC: 2014 Sep 9.
Published in final edited form as: Curr Opin Pharmacol. 2009 Jul 21;9(4):507–513. doi: 10.1016/j.coph.2009.06.021

Figure 1.

Figure 1

Diverging roles of high or low extracellular ATP concentrations in shaping the immune response. Panel A: Tissue cells release large ATP amounts in response to high pathogen titers. The increase in extracellular ATP level drives inflammatory dendritic cell (DC) and macrophage (Mϕ) differentiation, accompanied by release of pro-inflammatory mediators (TNF-α, IL-12, IL-1β, ROS), naive TH cells to TH1 lymphocyte differentiation and initiation of inflammation. Panel B: In response to low grade stimulation by pathogens, tissue cells release modest amounts of ATP which cause down-modulation of pro-inflammatory cytokines, preferential release of immunodepressive cytokines, differentiation of naive TH cells into TH2 lymphocytes, and a state of immunosuppression or allergy.