Activated NK cells kill activated, but not resting, CD4⁺ T cells.

Abstract

<p>(A) Representative gating strategy. NK cells were defined as viable, CD3⁻ singlets. NK cell subsets were defined based on expression of CD16 and CD56. (B) Activation of CD4⁺ T cells was confirmed by CD69 upregulation. CD4⁺ T cells were activated for 4 days with anti-CD3+anti-CD28 Dynabeads (propionate was added on day 3). Resting CD4⁺ T cells were unstimulated in media for 4 days. (C–D) NK cells were cultured for 4 days in IL-2, and CD4⁺ T cells were activated as described. Resting CD4⁺ T cells were unstimulated for 4 days in culture. Autologous NK cells and CD4⁺ T cells were co-cultured at an E∶T ratio of 1∶1 for 4 hours with FITC-conjugated anti-CD107a+anti-CD107b mAb. Flow cytometry was performed to determine CD107a/b expression on NK cell subsets. Data shown in (C) are for a representative donor, (D) are for n = 9. Data represent mean ± SEM. * <i>P</i><0.05; *** <i>P</i><0.001. (E) Sorted CD56^dim (□/▪) and CD56^bright (○/•) NK cells were cultured in media (□/○) or IL-2 (▪/•) for 4 days, and co-cultured with ⁵¹Cr-labeled activated CD4⁺ T cells in a ⁵¹Cr-release assay. Experiment shown is representative of n = 3.</p