Pandemic H1N1 vaccination induced CD8
T cell proliferation to pandemic H1N1, seasonal H1N1 and H3N2 peptides. CFSE-labeled PBMCs (1 × 106) were stimulated with 10 μg/ml of the pandemic H1N1 and seasonal H1N1 and H3N2 peptides for 7 days. The cells were harvested and stained with anti-human CD3PE-Texas Red and CD8PE-Cy7 and analyzed using flow cytometry. (a) Percentages of the CD8+ T cell proliferation pre-vaccination and post-vaccination in response to seasonal H1N1 and H3N2 peptides. The means and standard errors are shown, with p ≤ 0.05 pre-vaccination vs. post-vaccination, according to the Wilcoxon matched-pairs signed rank test. (b) Percentages of positive subjects responding to the pandemic H1N1 peptides 1 and 2 (p < 0.05) and the seasonal influenza A H1N1 (p < 0.05) and H3N2 serotypes post-vaccination (p > 0.05).