BTLA-HVEM interaction inhibited γδ T-cell proliferation. (A) Circulating γδ cells from HV were purified and cultured with IL-2±25 to 1000 nM BrHPP during 5 days (n = 3). Proliferation was quantified by CFSE dilution and represented as the percentage of divided cells among γδ T cells. (B) Characterization of HVEM mAbs. Stable transfectants LTK-HVEM were pre-incubated for 1 hour with the indicated concentrations of anti-HVEM (HVEM 11.8 and HVEM 18.10), followed by the addition of human BTLA-Fc (10 µg/mL). Then transfectants were incubated for 30 minutes with GAH-PE (IM1626 Immunotech 1/100). PD1-3 mAb was included in the same conditions as the nonblocking control. Results were normalized by dividing MFI of HVEM mAbs by MFI of PD1-3.1 mAb (baseline level). (C-D) CellTrace dilution in purified-γδ T cells from 4 HV stimulated 5 days with or without low-dose BrHPP (50 nM) with specified mAb or Fc proteins. Results were expressed as mean ± SEM, and statistical significance was established using the nonparametric paired Wilcoxon U test. *P < .05; **0.001 < P < .01; ***P < .001.