FIG. 1.

RICK deficiency leads to reduced IL-1β and IL-6 production in response to P. aeruginosa infection in macrophages prestimulated with LPS. Macrophages from wild-type (WT) and RICK-deficient (RICK knockout [KO]) mice were left untreated (−) or stimulated with LPS (100 ng/ml) for 24 h and then infected with live P. aeruginosa strain PAK at various macrophage/bacterium ratios for 24 h (A to C) or treated with LPS (10 ng/ml) for 24 h (D). Cell-free supernatants were analyzed for the production of IL-1β (A), TNF-α (C), and IL-6 (B and D) by ELISAs. Values that were significantly different from the control value (no pretreatment) are indicated as follows: *, P < 0.05; **, P < 0.01. Results are shown as the means plus standard deviations (error bars) of triplicate samples. The results of this experiment are representative of those of five independent experiments. 1° Tx, first treatment; 2° tx, second treatment.