NKp80-mediated recognition and lysis of monokine-activated NK cells by autologous NK cells. (A-B) NK cells were purified from freshly isolated PBMC and cultivated in parallel for 2 days in the presence of IL-2, IL-12 and IL-18 (activated NK cells) or without cytokines (resting NK cells), respectively. Subsequently, activated NK cells were labeled with CFSE and cocultured with resting NK cells of the same donor in the presence of blocking F(ab)2 fragments of mAb 5D12 (anti-NKp80) or of an isotype-matched IgG1 control. Subsequently, cultures were analyzed by flow cytometry for degranulation (CD107a+ cells) and production of IFN-γ or TNF. (A) Representative dot plots of resting (CFSE−) NK cells stained for CD107a, IFN-γ, or TNF, after coculture with autologous monokine-activated NK cells or, for control, without coculture. (B) Compiled data from independent experiments of TNF responses or degranulation of resting (CFSE−) NK cells after coculture with activated autologous NK cells or, for control, without coculture. Each value represents the mean of triplicates from a single experiment. P values were determined using the Wilcoxon signed-rank test. (C-D) Monokine-activated NK cells are lysed by autologous resting NK cells in an NKp80-dependent manner. Activated NK cells were labeled with 51Cr (target cells, T) and incubated with resting NK cells of the same donor (effector cells, E) that had been preincubated with blocking F(ab)2 fragments of mAb 5D12 (anti-NKp80) or of an isotype-matched IgG1 control. (C) Representative cytolysis data for 2 donors. Means of triplicates are shown with standard deviations. (D) Compiled cytolysis data for 6 different donors at an E:T ratio of 20:1.
