FIG. 5.

Vaccination with pCIOmp31 elicit CD8⁺- and CD4⁺-specific T cells that lyse Brucella-infected macrophages in vitro. Cytotoxicity was detected in a standard 6-h ⁵¹Cr release assay. The effector/target cell ratio was 100:1. A. Target cells were A20J, A20JOmp31, J774, or J774 B. ovis. Effector cells were the splenocytes from pCIOmp31- or pCI-immunized mice previously cultured for 5 days with mitomycin C-treated A20JOmp31. Each value represents the mean ± SD of the responses of spleen cells from five individual mice. Data are representative of two separate experiments. ★, significantly different from pCI-immunized mice (P < 0.05). B. Target cells were J774 B. ovis. Effector cells from pCIOmp31-immunized mice were depleted of CD4⁺ T cells (−CD4⁺) or CD8⁺ T cells (−CD8⁺) or were not depleted (total cells) as indicated in Fig. 4. Depleted and nondepleted effector cells were preincubated for 2 h with RPMI (-), BFA, or CCA. Each value represents the mean of triplicates ± SD of the response of a pool of spleen cells from five mice. Data are representative of three separate experiments.