Figure 4.

Soluble IL-18 secreted by cancer cells and HCMV-infected cells enhances IFNγ production by human Vδ2^neg γδ T cells, in a TCR-dependent manner. (A) Conditioned culture supernatants of various cancer cell lines, or fresh media, were isolated after 48 h at 37°C, cleared by centrifugation, and incubated with a Vδ1 γδ T polyclonal cell line in the presence of various concentrations of coated anti-CD3 for 24 h at 37°C. IFNγ secretion was then measured by ELISA from cell culture supernatants (mean ± SD; n = 3). Results are normalized by the same amount of cells used for each cancer cell line. (B) Conditioned culture supernatants from various amounts of U373MG cancer cells, or fresh media, were isolated after 48 h at 37°C, cleared by centrifugation, and incubated with a Vδ1 γδ T polyclonal cell line in the presence of anti-CD3 for 24 h at 37°C. IFNγ secretion was then measured by ELISA from cell culture supernatants (mean ± SD; n = 3). (C) Conditioned culture supernatants of U373MG cancer cells, or HUVECs infected or not with HCMV (MOI 10), or fresh media, were isolated after 48 h at 37°C, cleared by centrifugation, and incubated with Vδ2^neg γδT cells in the presence of anti-CD3 with or without anti-IL-18 or control anti-IL-10 antibodies (10 μg/mL). After 24 h at 37°C, IFNγ secretion was measured by ELISA from cell culture supernatants (mean ± SD; n = 3). As indicated, Vγ2Vδ3 T cell clone, Vδ1, and Vδ1+3 polyclonal cell lines were tested. ^★, P < 0.05.