KIR-KIRL mismatch constellations boost the capacity for degranulation and cytokine synthesis of KIR⁺ NK cells toward pediatric BCP-ALL. Sorted KIR⁺ and KIR⁻ NK cells of the donors SNK13-15B and SNK20B (donor group “mismatch”) were cocultured with NALM-16 or K562 cells as a control to determine the functional response in terms of degranulation and cytokine synthesis. Pooled data of the intracellular staining showing mean ± SEM. Given are the percentages of the respective CD107a⁺, perforin⁺, TNF⁺, and IFN-γ⁺ NK-cell subpopulation, normalized to the corresponding baseline levels of NKAES cells cultured in control medium only. Note that due to the genuinely higher response, the y-axis is differently scaled in K562 experiments. The negative bars indicate the decline in perforin levels that accompanies NK-cell degranulation.