Purification of viable IFN-γ–secreting CD8⁺ T cells by FACSort.

Cells were prepared and stained as described in “Materials and methods.” (A) Nonstimulated control cells. (B) CD8⁺IFN-γ⁺ and CD8⁺IFN-γ⁻ cell subpopulations before sorting. (C) Purified CD8⁺IFN-γ⁺ and (D) purified CD8⁺IFN-γ⁻ cell populations. Both subpopulations were separately used for subsequent cytotoxicity assays. CD4⁺IFN-γ⁺ and CD4⁺IFN-γ⁻ cell subpopulations were purified accordingly.