FIG. 5.
Apoptotic cell death is reduced in IL-18ko/ko mice. C57BL/6 and IL-18ko/ko mice were infected with 50,000 listeriae. Spleens were collected at different time points, and the degree of apoptosis was determined by TUNEL staining as described in Materials and Methods. TUNEL-positive cells stain dark brown. Spleens were collected 24 h (A and B), 48 h (C and D), and 72 h (E and F) after infection with L. monocytogenes. Bar, 100 μm. (G) C57BL/6 or IL-18ko/ko mice were infected with 5,000 listeriae, and spleens were taken at the indicated time points after infection. Mice without (w/o) infection were used as controls. RNA was isolated, and IFN-β levels were determined in triplicate using quantitative reverse transcriptase PCR. Relative expression is shown using glyceraldehyde-3-phosphate dehydrogenase as a standard. Data are derived from three mice per group.