Detection of the KIR2DS1⁺ NK-cell subset in a C1/C1 donor. Double fluorescence analysis was performed using purified peripheral blood NK cells derived from the C1/C1 Bw4/Bw4 donor P61. For staining, the following mAbs were used in combination: anti-KIR2DL1/S1-FITC (clone 11PB6) and anti-KIR2DL1-PE (clone143211). (A); anti-KIR2DL1/S1-FITC (clone 11PB6) and a mixture of anti-KIR2DL2/L3/S2 (Y249), anti-KIR3DL1/L2/S1 (AZ158), anti-NKG2A (Z199) followed by PE isotype-specific secondary reagents and anti-KIR2DL1-PE (clone 143211). (B). Numbers in upper quadrants indicate the percent of positive cells.