Figure 2. Ty21a elicited Salmonella-specific functional CD4+ T_EM cells.

Post-vaccination peak increases in functional CD4 T_EM (CD45RA−CD62L−) cells obtained from Ty21a immunized volunteers (n=16) that produced cytokines (i.e., IFN-γ, TNF-α, IL-2) or expressed CD107a in response to S. Typhi (A), S. Paratyphi A (B) and S. Paratyphi B (C)–infected targets were measured as described in the text. These functional cells were segregated into Single+ cells (S+; producing only one cytokine or expressing just CD107a [107a]) and multifunctional (MF; simultaneously producing two (2+), three (3+) or four (4+) cytokines and/or expressing CD107a. Bar graphs represent the mean+SE (error bar) of percentages of total functional cell for each of the subsets ( [subset]/[sum of S+ and MF cells] X100). Post-vaccination peak increases were calculated as peak levels at days 42 or 84 post-vaccination minus the corresponding pre-vaccination levels. Statistical analysis:

***: p<0.001, **: p<0.01, *: p<0.05, #: p=0.06 by Wilcoxon paired t-test, 2 tail