TABLE 3.

Increased resistance of Csf1^op/Csf1^op mice to L. monocytogenes following CSF-1, IFN-γ, or IL-6 administration

Cytokine treatment	Mean (±SEM) CFU of L. monocytogenes ind:
	Spleen	Liver
CSF-1a
No CSF-1	4.5 × 105 ± 8.9 × 104	2.6 × 106 ± 4.6 × 105
CSF-1	3.2 × 104 ± 3.4 × 103*	7.9 × 104 ± 1.0 × 104*
IFN-γb
No IFN-γ	3.3 × 106 ± 3.9 × 105	1.0 × 106 ± 5.0 × 104
IFN-γ	4.1 × 105 ± 7.9 × 104*	1.2 × 105 ± 2.9 × 104*
IL-6c
No IL-6	Not done	2.0 × 107 ± 3.0 × 106
IL-6	Not done	4.1 × 105 ± 6.8 × 104*

^aCsf1^op/Csf1^op mice (six per group) were given CSF-1 for 3 days before infection with 10⁴ L. monocytogenes. At 48 h. p.i., mice were sacrificed and CFU recovered from liver and spleen were enumerated. 

^bMice were given IFN-γ in a single injection (10⁴ IU) i.v. 2 h before infection with 10⁴ L. monocytogenes. Mice were grouped as in a above. CFU enumeration was performed as for the CSF-1 group. 

^cMice were injected with rIL-6 at day −1, 0, and +1 p.i., and CFU recovered from liver were enumerated 48 h p.i. The experiment was repeated once with similar results. 

^d∗, P < 0.001, Student's t test;Not done, spleens were used for in vitro studies.