Figure 4.

CD8⁺ T lymphocyte protective secondary responses are impaired in N-ras–deficient mice. (A) WT and N-ras^−/− mice were injected with unpulsed mDC or mDC pulsed with B8R and OVA peptides. On day 35, mice were infected i.p. with rVACV-OVA and, 5 d later, IFN-γ production by B8R- and OVA-specific splenic and PEC CD8⁺ T lymphocytes was determined ex vivo (n = 4, two experiments). ***, P < 0.0005. (B) Mice primed with B8R-pulsed mDC were challenged with VACV intradermally in both ear pinnae on day 35. On indicated days after challenge infection, lesion diameter was determined with a digital caliper (n = 6 for unprimed mice, n = 8 for B8R-loaded mDC-primed mice; two experiments). Results in A and B are expressed as mean ± SEM. Statistics was performed comparing unprimed versus primed mice for either WT or N-ras^−/− mice. (C) Infectious virus titers in the ears and frequency of B8R-specific T lymphocytes within the CD8⁺ population in the draining retromaxillar lymph nodes (bottom dot plots) were determined 6 d p.i. (n = 6 for mDC-injected mice, n = 12 for B8R-loaded mDC-primed mice, two experiments). Horizontal bars show the mean values. ***, P < 0.0005.