Mouse DCs from IL-15-deficient mice induce alloreactive T-cell activation. (A) DCs (5 × 10⁵) were stimulated with zymosan A in 24-well plates, and 1 × 10⁶ CSFE-labeled CD4⁺ or CD8⁺ allogeneic T cells were added to the culture. Cycling cells were analyzed at the indicated time points by FACS analysis. (B) Expression of the indicated molecules by unstimulated DCs (solid lines) or DCs that had been activated by zymosan A for 18 hours (dotted lines) were analyzed by flow cytometry. (C) After 48 hours of culture, CD69 expression was evaluated on small noncycling T lymphocytes (solid lines) and large T-cell blasts (dotted lines). This experiment represents 1 of 2 independent experiments with comparable results.