Figure 1.

Identification of T-cell subsets. (a) Gating strategy to identify T cells, based on expression of CD3, CD8α, CD8β and CD4. (b) T-cell frequencies. CD8αα⁺, CD4⁺ CD8αα⁺ and CD4⁺ CD8αβ⁺ T-cell frequencies were statistically higher in non-human primates. P <0·001 (Mann–Whitney U-test).