Table 2.

Synergy between NPs and endotoxin in causing biological effects in human primary monocytes

		Gene expression (AU)b
Treatmenta		IL-18		IL-18Rα
		no NPs	AgO NPs	no NPs	AgO NPs
4 h	medium	0.77 ± 0.40	0.98 ± 0.20 n.s.	0.49 ± 0.04	0.47 ± 0.13 n.s.
	endotoxin	3.57 ± 0.80	3.04 ± 0.03 n.s.	0.65 ± 0.16	1.78 ± 0.37*
24 h	medium	0.92 ± 0.11	0.92 ± 0.25 n.s.	0.27 ± 0.12	0.82 ± 0.56 n.s.
	endotoxin	0.31 ± 0.05	0.17 ± 0.05 n.s.	18.56 ± 1.86	10.17 ± 2.01*

^a Human monocytes were exposed for 4 and 24 h to culture medium alone or to medium containing 50 EU/ml endotoxin. At the beginning of the incubation, cells were exposed to endotoxin-free AgO NPs (4.9 μg/ml, corresponding to a dilution at 4.55% v/v). Controls were cells exposed to culture medium alone or to a 4.55% dilution of the solvent (no detectable difference).

^b Gene expression was assessed by real-time PCR, using β-actin as housekeeping gene. Data are mean ± SD of replicate experiments.

* p < 0.05 vs. corresponding treatment in the absence of NPs; n.s. not significant vs. corresponding treatment in the absence of NPs