Figure 1. IFN-γ production by Vγ9Vδ2 T cells is induced by Brucella-infected DCs and required cell-cell contact.

A/ Correlation between the MOI used to infected DCs and IFNγ production by Vγ9Vδ2 T cells. DCs infected or not with different MOI (2, 5, 20, and 50) were cultured alone or in the presence of Vγ9Vδ2 T cells. At 24 h and 48 h p.i., supernatants were collected and the concentration of IFN-γ was assayed by ELISA test. A significant difference between infected DCs in the presence or not of Vγ9Vδ2 T cells was calculated by using a Student’s t test and is indicated by (*) where p<0.05 and (**) where p<0.01. Data shown are the mean +/− SD of triplicates and are representative of three experiments performed with cells from different donors. B/ Intracellular accumulation of IFN-γ in Vγ9Vδ2 T cells. Untreated or stimulated (0.2 nM HMB-PP) Vγ9Vγ2 T cells were cocultured with non- or Brucella-infected DCs (MOI = 20). At 24 h p.i., intracellular IFN-γ was analyzed in Vγ9Vδ2 T cells by flow cytometry. The Student’s t test was used to calculate significant differences between: 1- infected DCs in the presence or not of Vγ9Vδ2 T cells and were indicated by (*) where p<0.05 and (**) where p<0.01 and 2- untreated or HMB-stimulated Vγ9Vδ2 T cells and were directly indicated on the graph. Data shown are the mean +/− SD of three independent experiments. C/ IFN-γ production requires cell-cell contacts between infected DCs and Vγ9Vδ2 T cells. Brucella-infected DCs (MOI = 20) were cocultured with Vγ9Vδ2 T cells in contact or separated by a trans-well chamber system (insert). At 48 h p.i., supernatants were collected and IFN-γ was measured by ELISA. The Student’s t test was used to calculate significant differences between: 1- infected DCs in the presence or not of Vγ9Vδ2 T cells and was indicated by (**) where p<0.01 and 2- Vγ9Vδ2 T cells in contact or not with infected DCs was directly indicated on the graph. Data shown are the mean +/− SD of triplicates and are representative of three independent experiments.