Percentages (A) and absolute numbers (B) of relevant immune cell populations before (Wk 0) and up to 8 weeks after TT booster vaccination.

<p>(A) Percentages of CD3⁺, CD3⁺CD4⁺, CD3⁺CD8⁺ and CD3⁺CD4^-CD8^- cells were determined on viable PBMNC prior to cell culture by flow cytometry, gating on singlets first, and then on the lymphocyte population. A minimum of 100000 events were acquired. Combined staining for CD45RA and CCR7 allowed discrimination of Naïve (CD45RA⁺ CCR7⁺), Memory (CD45RA^-), central memory, T_CM (CD45RA^- CCR7⁺) and effector memory, T_EM (CD45RA^- CCR7^-) CD3⁺CD4⁺ cells. (B) The absolute number of cells was calculated from the blood lymphocyte counts available for subjects 1, 2 and 3 (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0136717#pone.0136717.t001" target="_blank">Table 1</a>), and the phenotypic data.