Proliferative response of iNKT cells to IL-15. (A) CD8-depleted thymocytes, CB cells, or PBMCs were stained with CFSE and cultured for 7 days in the presence of IL-15 and anti-CD1d blocking mAb (left) or 6B11-coated plates plus IL-15 (right). iNKT cells were identified with PE-6B11 and plotted against CFSE-fluorescence. (B) Distribution of CFSE-fluorescence in CD4⁺ versus CD4^- subsets of iNKT cells from adult PBMCs cultured with IL-15 + anti-CD1d mAb. Representative diagrams from 8 independent experiments are shown.