TABLE 2.

Nitrite concentrations in culture supernatants of S. flexneri-infected J774 macrophage cells, L2 fibroblast cells, and bone marrow macrophages from either C57BL/6 or NOS2^−/− mice^a

Activator (concn)	Nitrite concn (μM)
	J774 cells	L2 cells	Bone marrow macrophages
			C57BL/6	NOS2−/−
None	<1.6b	<1.6	<1.6	<1.6
IFN-γ (100 U/ml)	1.6	<1.6	4.6	<1.6
IFN-γ + aminoguanidine (2 mM)	<1.6	<1.6	NDc	ND

^aNitrite concentrations were evaluated 4.5, 24, and 6 h postinfection for J774 cells, L2 cells, and bone marrow macrophages, respectively. 

^b<1.6 μM, below the limits of detection. 

^cND, not determined.