Table I. Induction of NO production by IL-12 in BV-2 glial cells.

BV-2 glial cells were cultured for 24 h in serum-free DMEM/F-12 with the listed reagents, and nitrite concentration in the supernatants was measured as described under “Materials and Methods.” Arginase (100 units/ml), L-NMA (0.1 mM), and D-NMA (0.1 mM) were added to the cells together with IL-12. Data are mean ± S.D. of three different experiments.

Treatments	Nitrite
	nmol/mg/24 h
Control	4.3 ± 0.5
IL-12 (1 ng/ml)	35.6 ± 4.1
IL-12 (2 ng/ml)	66.3 ± 7.1
IL-12 (5 ng/ml)	85.5 ± 9.8
IL-12 (10 ng/ml)	86.3 ± 8.7
IL-12 (5 ng/ml) + Arginase	8.4 ± 1.0
IL-12 (5 ng/ml) + L-NMA	12.9 ± 1.5
IL-12 (5 ng/ml) + D-NMA	83.7 ± 7.5