Figure 1.

Identification of PD-1-expressing CD4⁺ and CD8⁺ T cells. (A) Gating strategy to identify CD4⁺ and CD8⁺ T cells. Lymphocytes were gated based on FSC/SSC profile. CD3+ T cells were identified within the lymphocyte gate to separate CD4⁺ T cells and CD8⁺ T cells. (B and C) Representative dot plots of PD-1 expression on CD8⁺ T cells (B) or CD4⁺ T cells (C) in medium condition and after stimulation of PBMCs with anti-CD3. CD3+ CD8⁺ T cells or CD3+ CD4⁺ T cells were analysed and frequency of PD-1⁺ CD8⁺ T cells (B) or PD-1⁺ CD4⁺ T cells (C) at day 2 and day 7 were compared with the frequency at baseline (day 0). Values in the upper right quadrant indicate the percentage of PD-1 positive cells within CD8⁺ or CD4⁺ T cells.