Figure 1. CD4⁺ CD28⁺ T_EM subset exhibits high proliferative capacity and cytokine functionality and low frequencies of apoptotic cells following stimulation with alloantigen.

Responder PBMCs were stimulated in the presence or absence of irradiated, CTV labeled, allogeneic stimulator PBMCs. Risky memory T cell subsets were defined by the following gating strategy: CD4⁺ CD28⁺ T_EM, CD3⁺ CD4⁺ CCR7⁻ CD45RA⁻ CD28⁺; CD8⁺ CD28^null, CD3⁺ CD8⁺ CD28⁻; CD4⁺ CD57⁺ PD1⁻, CD3⁺ CD4⁺ CD57⁺ PD1⁻. (A) Representative flow plots and summary data of frequencies of Ki-67⁺ proliferating cells within risky memory T cell subsets in the presence or absence of allogeneic stimulation. (*, p < 0.05; data depicted are from six independent stimulator/responder pairs). (B) Representative flow plots and summary data of frequencies of Caspase3/7⁺ 7-AAD⁺ apoptotic cells within risky memory T cell subsets in the presence or absence of allogeneic stimulation (**, p < 0.01; *, p < 0.05; data depicted are from eight independent stimulator/responder pairs). (C) Representative flow plots and summary data of frequencies of TNF-, and IFN-γ-secreting cells within risky memory T cell subsets in the presence or absence of allogeneic stimulation (*, p < 0.05; data depicted are from six independent stimulator/responder pairs).