Exemplary cytokine profiles obtained with 2 DNAM-1-positive (UPN34 and UPN20) and 1 negative specimen (UPN18) as control are shown in Fig. 2A. Treatment with DNAM-1 ligands potently stimulated cytokine release in the positive samples, whereas no effect was observed with DNAM-1-negative leukemia. This evidence concerns the gene CD226 and leukemia.