TNF and Sepsis: The stimulation of healthy individual monocytes with LPS, but not IL-6, TNF-α, or IFNγ, increased the surface expression of P2X7 receptors (Fig. 4e, f), suggesting that bacterial infections rather than the pro-inflammatory cytokines that are present during the initial phase of sepsis are responsible for the increase in P2X7 receptor expression observed during sepsis.