CD1D and neoplasm: iNKT cells treated with the 6B11 mAb degranulated toward CD1d-negative Daudi and CD1d+ U937 cells, but not toward CD1d-negative A549, CD1d-negative PC13, or CD1d+ Jurkat cells, indicating that CD1d expression on tumor cells was not required for this antitumor activity of iNKT cells induced by 6B11 mAb treatment (Fig. 3B).