Analysis of degranulation capacity in NKp46-defined NK-cell subsets in blood. The cytolytic capacity of NKp46-defined NK-cell subsets (CD8α+NKp46-: blue, CD8α+NKp46+: green) isolated from blood was analysed after receptor triggering. Cells were stimulated with rhIL-2 and rpIL-15 overnight. Triggering of NK-receptors was performed by using monoclonal antibodies against NKp46, CD16 or a combination of both. Irrelevant isotype-matched antibody served as negative control. NK-cell receptor mediated degranulation was assessed by measuring the expression of CD107a on the cell surface by four-colour flow cytometry after one hour incubation. CD107a expression was measured on CD3- lymphocytes (not shown), followed by gating on the respective NKp46-defined NK subsets. (A) Numbers indicate the percentage of CD107a+ cells and the mean fluorescence intensity of CD107a within respective NKp46-gates. Results are representative of experiments with five different animals. (B) CD107a expression analyses of five animals analysed. The proportion of CD107a+ cells within the different NKp46-defined subsets is shown in the upper graphs. Percentage of CD107a+ NK cells was calculated by subtracting spontaneous degranulation observed in cultures stimulated with isotype-control antibodies from the frequency of CD107a+ cells in cultures stimulated with NKp46 and/or CD16 mAbs. The lower graphs show the mean fluorescence intensity of CD107a within the respective subsets. Mean values are represented by a black bar. Significant differences between the subsets are indicated (* = p < 0.05, ** = p < 0.01).