TABLE 2.

Downregulation of the DNA-binding activity of the p65 subunit of NF-κB in FimA tolerance in THP-1 cells^a

Cell stimulation (primary/secondary)	NF-κB subunit activation (OD450)
	p50	p65
Medium/medium (baseline control)	0.187 ± 0.068	0.052 ± 0.019
Medium/native fimbriae	2.124 ± 0.548	1.378 ± 0.279
Native fimbriae/medium	1.779 ± 0.354	0.176 ± 0.035*
Native fimbriae/native fimbriae	2.007 ± 0.432	0.389 ± 0.072*
Medium/rFimA	1.693 ± 0.267	1.401 ± 0.321
rFimA/Medium	1.382 ± 0.298	0.209 ± 0.039*
rFimA/rFimA	1.538 ± 0.403	0.432 ± 0.090*

^aTHP-1 cells were pretreated for 20 h with medium only or with 1 μg of native fimbriae or rFimA per ml. Subsequently, the cells were washed, rested for 2 h, and restimulated for 1 h as indicated with the stimuli at the same concentration as in pretreatment. NF-κB activation in cellular extracts was analyzed with an NF-κB p50/p65 ELISA-based kit. OD₄₅₀, optical density at 450 nm. The results are shown are means ± standard deviations (n = 3). Asterisks indicate statistically significant (P < 0.05) inhibition of the DNA-binding activity of NF-κB subunits in tolerant cells with or without restimulation.