Target cell–induced IFNγ production, but not CD107a expression, is decreased after allogeneic transplant. PBMCs from healthy donors and recipients 3 months after T-cell replete, T-cell deplete, and UCB HCT were incubated with media alone, K562 cells, or IL-12/IL-18. CD107a expression and IFNγ production were measured on CD56⁺CD3⁻–gated NK cells. Representative FACS plots are shown. The numbers in each quadrant are the percentages based on total CD56⁺CD3⁻ NK cells.