rIL-2 and rIL-15 enhance the conversion of peripheral CD4⁺ T cells to CD4⁻ cells via allogeneic mature BM DC stimulation. (A) Flow cytometry of CFSE-labeled T-cell proliferation induced by allogeneic mDCs and cytokines. CD4⁺CD25⁻ (CD4⁺CD25⁻) and CD4⁺CD25⁺ (Treg) T cells from C57BL/6 mice were stimulated with mature DBA/2 DCs plus rIL-2 or rIL-15 for 5 days. CD3⁺ T cells were gated and used for CFSE analysis. (B) Flow cytometry of CD4⁻ cells converted from C57BL/6 CD4⁺ T cells via mature DBA/2 DC stimulation. Numbers beside outlined areas indicate the percentage of cells in the designated gate. (C) CD4⁻ cells appeared only after several cycles of cell proliferation induced by allogeneic mDCs. (D) At equivalent concentration to support alloantigen-triggered CD4⁺ T-cell proliferation, rIL-2 and rIL-15 exert similar potency to enhance the conversion of CD4⁺ into CD4⁻ T cells. The horizontal bars gate the nondividing cells, and the numbers refer to the percentage of these cells.