Cytotoxicity assay using a mixture of target cells with and without

PIG-A mutation. In the coexistence ofPIG-A mutant and control cells, NK cells preferably killed control cells than the mutant cells. Columns 1 and 2, control (GPI⁺) and PIG-A mutant (GPI⁻) K562 cells, respectively; columns 3 and 4, mixtures of the same number of control and the mutant cells. In the mixtures, only GPI⁺cells (column 3) and GPI⁻ cells (column 4) were distinctively labeled with ⁵¹Cr. The target cells were then cocultured with NK cells (2E3) at E/T ratio (2:1). Each value represents the mean (± SD) of triplicate assays.