TABLE 2.

Effects of exogenous IL-1β and IL-18 on antibacterial host defense in cas-1^−/− mice^a

Treatment	Dose	No. of mice that died/total no. (% mortality)
Salinec		6/6 (100)
IL-1βd	500 IU	1/7 (14)b
IL-18d	10 ng	0/3 (0)b

^acas-1^−/− mice were treated with recombinant mIL-1β (500 IU/mouse) or mIL-18 (10 ng/ml) 2 h prior to infecting them with 12,000 CFU of E. coli (Bort) per mouse and observed for mortality.

^bSignificantly different from saline-treated cas-1^−/− mice: P = 0.0047 for IL-1β treatment and P = 0.0119 for IL-18 treatment by Fisher exact test.

^cTwo of two cas-1^−/− mice pretreated with heat-inactivated IL-18 prior to infection with 12,000 CFU of E. coli died by 48 h.

^dIL-18 and IL-1β contained <1 ng of endotoxin/μg as measured by Limulus amebocyte lysate assay (Associates of Cape Cod, Falmouth, Mass.).