Fig. 2.

Time course of IL-6 secretion and mRNA expression by RAW 264.7 cells treated with LPS, PA, or both LPS and PA. A and B: RAW 264.7 cells were treated with 1 ng/ml LPS, 100 μM PA, or both LPS and PA for different times as indicated. At each time point, culture medium was collected and RNA isolated from cells. IL-6 in culture medium (A) and IL-6 mRNA (B) in cells were quantified using ELISA and real-time PCR, respectively. The presented data (means ± SD) were from 1 of 3 experiments with similar results. The lack of bars (SD) on some points is due to the fact that the SD was too small to be shown on the figure. C: the effect of LPS or the combination of LPS and PA on IL-6 mRNA stability. RAW 264.7 cells were treated with 1 ng/ml LPS or 1 ng/ml LPS + 100 μM PA for 12 h, followed by addition of 10 μg/ml actinomycin D. The cells were harvested 2 h after the addition of actinomycin D, and IL-6 mRNA was quantified using real-time PCR. The data presented (means ± SD) were from 1 of 2 experiments with similar results. + and *P < 0.01; * and **P > 0.05. Different symbols represent significantly different values.