Fig. 5. Early CD8 responses to MVA are attenuated in old monkeys.

(A) The frequency of IFNγ responders in CD28⁺ and CD28⁻ subsets of individual adult monkeys at day 7 post vaccination was pairwise compared by Wilcoxon signed rank test and p value is shown. Similar results (p=0.0039) were observed in old animals (not shown). (B) In vitro VACV stimulation was followed by FCM as in figure 1B. The frequency of CD28⁺ and CD28⁻ cells in CD62L⁻ IFNγ responders was calculated for each individual adult monkey and time point (see supportive figure 3 for gating). Means and SEM for each time point are shown. (C) The frequency of IFNγ responders in CD28⁺ subsets of adult or old animals was compared by Mann-Whitney test and p value is shown. Symbols indicate values relative to individual monkeys, horizontal bars indicate means. (D) Frequency of naïve CD8 lymphocytes prior to MVA immunization (x-axis) was correlated to IFNγ responses in CD62L⁻CD28⁺ cells at day 7 following infection (y-axis) in animals with less than 20% of naïve CD8 cells prior to vaccination. Symbols show values in individual adult (●) or old monkeys (△), the line shows the linear regression curve. (E) Naïve CD8 counts per ml blood prior to MVA immunization (x axis) was correlated to IFNγ responses in CD62L⁻CD28⁺ cells at day 7 following infection (y-axis) in animals old animals. Symbols show values in individual animals, the line shows the linear regression curve. (F) Immediate CD28⁺CD62L⁻ CD8⁺ T-cell IFNγ responses from Figure 2, panel C (x-axis) were correlated to antibody titers at day 14 post boost (y-axis). Values for individual adult (●) or old (△) animals, and the linear regression curve for combined datasets are shown.