Detection of donor-versus-recipient alloreactive NK-cell repertoires after NK-cell infusion. (A) Time kinetics of KIR2DL2/3/S2⁺/NKG2A⁻ NK cells from 7 HLA-C1–positive donors infused into HLA-C1–negative recipients. Such cells are potentially alloreactive because they contain KIR2DL2/3⁺ only NK cells (which are alloreactive against C1-negative recipients). (B) Time kinetics of KIR2DL1/S1⁺/NKG2A⁻ NK cells from 5 HLA-C2–positive donors infused into HLA-C2–negative recipients. Such cells are potentially alloreactive because they contain KIR2DL1⁺ only NK cells (which are alloreactive against C2-negative recipients). (C-D) After the NK-cell infusion, NK-cell clones were obtained from patients who received an infusion of NK cells (see “Methods”), and their alloreactivity against recipient PHA blasts was determined in a ⁵¹Cr-release assay. Each bar represents the degree of alloreactivity (percentage of specific lysis against recipient PHA blasts) exerted by one individual clone. All alloreactive clones, exhibiting ≥ 30% specific lysis, obtained from all patients are shown. (C) NK clones detected in 5 HLA-C1–negative recipients after NK-cell infusion from HLA-C1–positive donors. (D) NK clones detected in 3 HLA-C2–negative recipients after NK-cell infusion from HLA-C2–positive donors.