The development of human CD8⁺ T_EM and T_CM cells is regulated by both cytokine signaling and strength of primary activation. CD8⁺ CD45RA⁺ sorted cells were labeled with PBSE and polarized under neutralizing or IL-12 + IFN-α conditions with 1 μg/mL, 2.5 μg/mL, or 5 μg/mL anti–human CD3 and anti–human CD28 for 5 days. Cells were assessed for expression of IL-12Rβ2 (A) or IFNAR2 (B) as a function of division. Quantification of mean fluorescence intensity is displayed as a function of division for IL-12Rβ2 (A right panels) or IFNAR2 (B right panels) in neutralized (top panels) or IL-12 + IFN-α (bottom panels) cells.