Inhibition of the antitumor immune response by type II NKT cells in tumor-bearing mice. NS0-V or NS0-CD1 cells (10⁷) were injected intraperitoneally into BALB/c wildtype (), CD1KO (◇) and Jα18KO (♦) mice. On days −1, 5, 10, 20, 30, 40, and 50, the mice were injected intraperitoneally with 50 μg of isotype control antibody (A) or the anti-mouse CD1d antibody 1H6 (B). Tumor growth was monitored for 100 days. The results shown are pooled data from 2 independent experiments (4 mice/experiment; n = 8).