Figure 5.

Natural killer (NK) cells reduce the proportion of Th17 and Th1 cells in vitro. Memory CD4⁺ T cells and NK cells were isolated from healthy subject PBMC. Memory CD4⁺ T cells were CD3⁺CD4⁺CD45RO⁺CD45RA⁻ as shown in representative dot plots (A,B). NK cells were CD3⁻CD56⁺ as shown in a representative dot plot (C). Memory CD4⁺ T cells were cultured without (D,E), or with NK cells at a 1:1 ratio (F,G) for 4 days with anti-CD3, anti-CD28, and Th17 polarizing factors for 4 days. Plots are shown for CD4 × CD56, which was used to gate CD4⁺ helper T (Th) cells. Expression of IL-17 and IFN-γ by CD4⁺ T cells was assessed by intracellular flow cytometry (Th17 = CD3⁺CD4⁺IL-17A⁺IFN-γ⁻, Th1 = CD3⁺CD4⁺IL-17A⁻IFN-γ⁺, and Th1/17 = CD3⁺CD4⁺IL-17A⁺IFN-γ⁺). Data pooled from 12 experiments showing the proportion (H) and absolute number of Th cells (I). A time-course analysis for Th17 cells (J) and Th1 cells (K) was performed for 5 days using intracellular cytokine staining. Open diamond = T cells and closed square = T cells + NK cells.