Figure 1. Overexpression of PD-1 decoy increases IFN-γ secretion from T cells. Activated B6 splenic T cells were transduced with retrovirus carrying either a control vector (pMIG-w) or PD-1 decoy and rested for 3 days in the absence of stimulation. (A) Retroviral transduction efficiency was measured by flow cytometry using GFP. The GFP positive populations were gated and the expression levels of PD-1 were analyzed. PD-1 expression in the control represents the levels of endogenous PD-1, while the PD-1 decoy sample shows the levels of both endogenous and the decoy receptor. (Filled gray area: Isotype control, Percentage of GFP positive cells indicated inside histograms) (B) GFP positive T cells were sorted and stimulated with anti-CD3 in the presence of irradiated splenocytes for 48 hours. IFN-γ in the cultured supernatants was measured by ELISA (Student's t-test, ^*p<0.05, ^**p<0.01). Results are representative of 3 independent experiments.