DCs derived from NK-cell–primed monocytes through cell-to-cell contact via NKp30 promote CD8⁺T-cell activation and proliferation. Untreated and TNF-α–treated iDCs derived from NK-cell primed monocytes (NK-iDCs) were cocultured with purified, CFSE-stained naive allogeneic T cells for 5 days. DCs derived from monocytes alone (iDCs) or primed by NK cells through a Transwell membrane (NK//iDCs) were used as controls. By the fifth day of coculture, the phenotypical and functional profiles of T cells were assessed by flow cytometry. (A) Frequency of proliferating (CFSE^low) CD4⁺ T cells and CD8⁺ T cells stimulated by DCs at different conditions. (B) Frequency of proliferating (CFSE^low) CD8⁺ T cells stimulated by DCs derived from monocytes primed by NK cells in the presence of anti-NKp30 (α-NKp30) or IgG1,κ isotype control (IgG1,κ). (C) Frequency of proliferating (CD3⁺CFSE^low) CD45RO⁺CD4⁺ T cells and CD8⁺ T cells stimulated by DCs at different conditions. (D) Expression (MFI) of CTLA-4 and CD28 by proliferating (CFSE^low) CD4⁺ T cells and CD8⁺ T cells stimulated by DCs at different conditions. (E) Expression (MFI) of CD28 by proliferating (CFSE^lo) CD8⁺ T cells stimulated by DCs derived from monocytes primed by NK cells in the presence of anti-NKp30 (α-NKp30) or IgG1,κ isotype control (IgG1,κ). Error bars represent standard deviation. Data are representative of at least 2 or more independent experiments combined; n = 2-3 HDs per experiment. Statistical comparisons were performed with the unpaired Student t test with Welch correction. *P < .05, **P < .01, ***P < .001.