Protective antitumor immune response mediated by type I NKT cells to a murine B-cell lymphoma. (A) BALB/c wildtype (), CD1KO (◇), and Jα18KO (♦) mice were inoculated with 10⁷ NS0-V or NS0-CD1 cells. The results consist of the pooled data from 3 independent experiments (n = 20). The log-rank test was used to determine P values. Tumor incidence in mice inoculated with NS0-V cells compared with NS0-CD1 cells: wildtype, P = .537; in CD1KO, P = .6560; and in Jα18KO mice, P = .015. (B) BALB/c Jα18KO mice were inoculated with tumors as above and on days 0, 10, and 20, the mice received 2.5 × 10⁵ electronically-sorted type I NKT cells by adoptive transfer or sham, intravenously. The results shown are pooled data (4 mice/experiment; n = 8). The log-rank test was used to determine P values for tumor-bearing mice receiving sham treatment (●) or NKT cells (◇) and NS0-V (P = .6130) or NS0-CD1 cells (P = .0163).