KIR3DL1*009 segregates to a low density population on primary NK cells. A, Representative KIR3DL1 surface expression on the surface of primary NK cells (CD56+, CD3−) from a heterozygous KIR3DL1*001/*009 positive individual as detected by DX9 and Z27. B, RT-PCR amplification of KIR3DL1*001 (left panel) and KIR3DL1*009 (right panel) from sorted KIR3DL1 negative, low density, and high density populations. The lower and higher bands are the control and KIR specific amplicons, respectively. Representative flow cytometry histogram of KIR3DL1 surface expression on NK cells from individuals who express KIR3DL1*001 and KIR3DL1*009 (black, n=2), KIR3DL1*001 only (dashed, n=3), or KIR3DL1*005 only (grey, n=3).