Figure 1. Development of an assay of NK cell function.

(A) NK cell degranulation over time during incubation with different target cell lines at an effector:target ratio of 1∶5. The term ‘effector’ refers to the total number of peripheral blood mononuclear cells in the assay. (B) NK cell degranulation after 6 hr at effector:target ratios ranging from 5∶1 to 1∶40. (C and D). Reproducibility of the NK cell assay on different samples taken from individual healthy controls over several weeks (1–6) with a minimum interval of two weeks (individual circles). Closed and open circles on the left and right of each panel indicate values obtained when cells were incubated overnight prior to the assay in medium alone or medium plus IL-2 respectively. The data demonstrate the extent to which the assay is reproducible over time within an individual using a 6 hour incubation with K562 target cells and a 1∶5 effector:target ratio. Error bars represent standard deviations in all graphs in this figure.