Figure 4.

Cytotoxic activity of VACV-specific CD8⁺ T cells is not affected by the absence of CD4 help. (a) In vivo cytotoxic activity. Target cells, B8R-pulsed (CFSE^hi) and-unpulsed (CFSE^lo) splenocytes (1∶1), were transferred to i.n. infected mice (10³ PFU) at d10 pi. Six hours later, spleens were harvested and CFSE-labeled cells were analyzed by flow cytometry. Representative FACS histograms of live target cells and percent specific lysis are shown. (b) Ex vivo cytotoxic activity. Effector cells (B8R-specific CD8⁺ T cells) were prepared from splenocytes of i.p. infected mice (10³ PFU) at d10 pi. Effector cells were cultured with target cells at 5∶1 ratio (normalized to same total number of B8R-specific CD8⁺ T cells) for 6 h, and CFSE-labeled target cells were analyzed. Percent specific lysis is shown. Data are representative of two independent experiments with three to four mice per group. i.n., intranasally; i.p., intraperitoneally; ns, not significant; pi, post infection; VACV, vaccinia virus.