Despite intrinsic ADCC potential, Vδ2^neg γδ T cells do not kill HCMV-infected fibroblasts treated with anti-HCMV hyperimmune sera. (A) PBMCs from 1 representative HCMV-infected KTR were cultured with anti-CD16 mAb or control mAb, and degranulation was determined by staining with anti-CD107a mAb. Cells were then stained with a combination of anti-CD3, anti-Vδ2, and anti-TCRγδ mAbs, and analyzed by flow cytometry. (B) The results from 6 HCMV-infected KTRs are presented (P = .03 between control and anti-CD16 activation). (C) CD16^pos and CD16^neg Vδ2^neg γδ T-cell lines were activated with an anti-CD16 agonist mAb and/or an anti-CD3 mAb, at optimal (both at 10 μg/mL) or suboptimal doses (500 ng/mL for anti-CD16 and 250 ng/mL for anti-CD3). The cytotoxic potential of Vδ2^neg γδ T cells was measured by the flow cytometric CD107a assay. Data are representative of 3 different experiments. (D) Primary FSF cultures were infected or not with HCMV for 5 days, and then cells were harvested and incubated with anti-HCMV IgGs or control IgGs at the indicated concentrations. The binding of specific antibodies was revealed by flow cytometry using a fluorescent goat anti–human Ab. (E) The Daudi lymphoma and the A431 skin carcinoma cell lines were, respectively, incubated with anti-CD20 Rituximab and anti-EGFR Cetuximab (both at 10μg/mL). (F) The cytolytic activity of the CD16^pos Vδ2^neg γδ T-cell line against HCMV-infected FSF and tumor cells (Daudi and A431 cell lines) labeled with ⁵¹Cr and preincubated with polyclonal anti-HCMV IgGs, anti-CD20 Rituximab, and anti-EGFR Cetuximab, respectively, was measured after 4 hours at 37°C by analyzing the amount of ⁵¹Cr released in the supernatant. Data are representative of 3 different experiments.