TABLE 3.

Production of superoxide and nitric oxide by bovine macrophages incubated for 24 h with M. avium subsp. paratuberculosis or M. avium subsp. avium organisms (10 organisms/macrophage) with or without IFN-γ^a

Organism	Treatment	Mean superoxide production (nmol/mg of protein) ± SD	Mean nitric oxide production (μM) ± SD
Uninfected control	None	45 ± 1	0
M. avium subsp. paratuberculosis	None	42 ± 8	2.0 ± 0.3
	IFN-γ	19 ± 3*	6.9 ± 0.5*
M. avium subsp. avium	None	41 ± 5	2.5 ± 0.3
	IFN-γ	23 ± 3*	7.8 ± 0.6*

^aValues represent means for three cows. *, statistically significant (P < 0.05) compared to addition of organism alone.