Figure 2.

Exogenous TNF-α induces tolerance to subsequent TNF-α and LPS challenges.

Notes: THP-1 cells were stimulated with TNF-α (A, black bars) or LPS (B, striped bars) for 2 hours at which point they were washed and incubated with fresh medium for 14 hours before being challenged with TNF-α or LPS for 2 hours (C, black bars: primary stimulation TNF-α; striped bars: primary stimulation LPS). The nominal concentration of exogenous TNF-α was subtracted when preparing this graph. TNF-α or LPS induced tolerance to challenges from either stimulus. Data are representative of the mean ± standard deviation of two independent experiments analyzed in duplicate. Statistically significant compared with primary stimulations (*P<0.05, student’s t-test).

Abbreviations: TNF-α, tumor necrosis factor-alpha; LPS, lipopolysaccharide.