Donor-derived IL-15 is necessary for optimal IFN-γ production and CXCR3 expression by T cells in acute GVHD. (A) Wild-type B6D2F1 mice were lethally irradiated and underwent transplantation with 5 × 106 wt B6 splenic T cells and 1 × 107 TCD BM cells from either wt B6 or IL-15–/– B6 mice. Mice were killed 12 days after transplantation, serum harvested, and IFN-γ concentrations measured by cytometric bead array. Data represent mean plus or minus SEM from 1 of 2 similar experiments with a total of n = 8 mice per group. (B) Splenocytes were harvested from recipients of wt B6 or IL-15–/– B6 BM cells 5 days after transplantation, gated on CD4+ donor-derived (H-2Dd–) cells and costained for cell-surface expression of CXCR3. Data represent average (mean ± SEM) mean fluorescence intensity (MFI) values from n = 3 mice per group. The experiment was performed twice with similar results. (C) Representative flow cytometric plots from allogeneic or syngeneic recipients of wt B6 splenic T cells and either wt B6 BM cells or IL-15–/– B6 BM cells are shown.
