Primary NK cells were co-cultured with the lymphoma lines or the HLA-I-deficient cell line 721.221 (221) and then stained with an antibody panel that could distinguish between three populations of KIR2D-expressing cells; KIR2DL1/S1, KIR2DL1−KIR2DL2/S2+KIR2DL3−(KIR2DL2/S2+) or KIR2DL1−KIR2DL2−KIR2DL3+ (KIR2DL3+) (Fig. 5b and Supplementary Fig. 7). This evidence concerns the gene KIR2DL1 and lymphoma.