Inhibition of B-LCL-induced activation of Vγ8Vδ3 T cells by ILT2-Fc molecules and mAbs specific for ILT2 or MHC class I molecules. (A) The 73R9 γδ T-cell clone (Vγ8Vδ3) was preincubated for 15 minutes with either isotypic control mAb (IgG2a) or α-MHC-I mAb (W6/32, 10 μg/mL, MHC-I) and next stained with soluble human recombinant ILT2-Fc molecules (30 μg/mL). Values for MFI of ILT2 staining measured by flow cytometry are indicated. Control indicates secondary mAb alone. (B) The 73R9 γδ T-cell clone (Vγ8Vδ3) was incubated for 4 hours with an ILT2⁺ B-cell line (721.221, clone 39). Control mAb (IgG1, IgG2a), ILT2-Fc molecules (30 μg/mL), α-MHC-I mAb (W6/32, 10 μg/mL), or α-ILT2 mAbs (256, GHI-75, HP-F1, 10 μg/mL) were preincubated with either effector (left) or target cells (right), as indicated. CD107a/b mobilization was measured by flow cytometry, and values for the percentage of CD107a/b⁺ γδ T cells are indicated in the quadrants. Data are representative of at least 3 independent experiments.