IL-17⁺ Vγ9Vδ2 T cells promote IL-17–dependent production of β-defensin by epithelial cells. HT29 epithelial cells were incubated with IL-17⁺ Vγ9Vδ2 T cells in the presence or absence of IPP. In some experiments, neutralizing mAbs to IL-17 or isotype control mAbs were added to cultures. After 24 hours, supernatants were collected and β-defensins quantitated by commercially available ELISA. *P < .005 compared with all other groups.