Table 3.

Effects of LPS, IFN-γ and TNF-α on L-KYN and QUIN production in different cell types.

Cell origin	L-KYN (μM)				QUIN (nM)
	Control	LPS	IFN-γ	TNF-α	Control	LPS	IFN-γ	TNF-α
Blood macrophages	1.1 ± 0.1	15 ± 1*	20 ± 1*	4.0 ± 0.6*	215 ± 25	4450 ± 90*	4620 ± 94*	405 ± 74*
THP-1 (monocyte)	0.2 ± 0.1	26 ± 2*	41 ± 4*	0.3 ± 0.1*	6 ± 1	261 ± 35*	333 ± 8*	8 ± 2
U363MG (astrocytoma)	0.3 ± 0.1	2.1 ± 0.3*	43 ± 1*	0.8 ± 0.1*	<0.2	<0.2	<0.2	<0.2
SK-HEP1 (liver)	0.3 ± 0.1	0.6 ± 0.1*	38 ± 1*	0.6 ± 0.1*	<0.2	10 ± 2	523 ± 22*	0.7 ± 0.3*
WIL-NS (B-lymphocyte)	<0.05	0.4 ± 0.1*	0.8 ± 0.1*	0.1 ± 0.1*	<0.2	<0.2	<0.2	<0.2
MRC-9 (lung)	<0.05	0.5 ± 0.1*	41 ± 1*	0.6 ± 0.1*	<0.2	<0.2	<0.2	<0.2

Notes: Cells were incubated with or without (control) LPS (1 μg/mL), IFN-γ (100 unit/mL) or TNF-α (100 unit/mL). L-KYN (μM) and QUIN (nM) concentrations after 48 h incubation are expressed as means ± SEM from at least five incubation wells per time. Baseline L-KYN levels in the serum added to the incubation media (approx. 0.05 μM) have been subtracted. The minimum detectable concentrations were: QUIN < 0.2 nmol/L, L-KYN < 0.05 μM. For statistical comparisons, non-detected metabolites were set at the minimum detectable values.

^*Significant differences from respective control by one-way ANOVA and Mann-Whitney test.¹⁶