FIG 3 .

Phenotype and functional characterization of influenza virus-specific T cells. (A) Frequencies of influenza virus-specific T cells were determined via IFN-γ staining using ICS assays. (B) The memory phenotype of influenza virus-specific T cells was determined by the use of CD62L and CD45RA after stimulation with pH1N1 live virus, the M1 peptide pool, and the NP peptide pool of pH1N1. Characteristics of the virus-specific CD8⁺ T cells are shown on the first row in panel B, and those of virus-specific CD4⁺ T cells are shown on the second row in panel B. The cross-quadrant gate on the virus-specific T cells was determined by the gate of the PBMCs, shown on the third row in panel B. (C and D) The median ratios of each phenotype of the IFN-γ-secreting CD8⁺ T cells (C) and CD4⁺ T cells (D) from six individuals are shown in the pie graphs.