FIG. 3.

(A) Percentage of CD45RB^lo CD8⁺ peripheral blood lymphocytes in vaccinated and unvaccinated CD4-deficient and control B6 mice. Groups of five B6 or CD4-deficient male mice were vaccinated i.p. with 2 × 10⁴ ts-4 tachyzoites and bled 8 weeks later. Peripheral blood leukocytes were isolated and analyzed by flow cytometry. Bars show the percentages of CD8⁺ lymphocytes that exhibited the CD45RB^lo phenotype. These percentages were not significantly different between vaccinated CD4-deficient mice and B6 controls but were significantly greater in vaccinated mice of each strain than in corresponding unvaccinated controls (P < 0.05). (B) Numbers of CD45RB^lo CD8⁺ splenic lymphocytes in ts-4-vaccinated and unvaccinated CD4-deficient and control B6 mice. Groups of four B6 or CD4-deficient mice were vaccinated with 2 × 10⁴ ts-4 tachyzoites i.p., and their spleens were harvested 8 weeks later and analyzed by flow cytometry. Numbers of activated CD8⁺ splenic lymphocytes were not significantly different between vaccinated B6 and CD4-deficient mice, but numbers of those cells were significantly greater in spleens of vaccinated mice than in those of corresponding unvaccinated controls (P < 0.05).