Fig. 6.

Attenuation of lung and liver metastases (a), and of outgrowth of tumor cells cloned from DLN (b), in BALB/c mice receiving EMT6 tumor cells followed by surgical resection and immunization with EMT6 and CpG, along with adoptive transfer of splenocytes from “cured” CD200R1KO mice, is abolished by anti-CD4 (and less by anti-CD8) mAb. Groups of three mice received no cell transfer, or 30 × 10⁶ splenocytes intravenously in 300 μl PBS pooled from 5 CD200R1KO mice at 50 days post tumor resection, cells being given at 1 or 7 days post-immunization of the BALB/c mice. Mice subsequently received control Ig or anti-CD4/CD8 at 72 h intervals. All animals were sacrificed 28 days post tumor resection, and macroscopic tumor colonies counted (a). DLN cells were harvested from individual mice and cultured under limiting dilution for 3 weeks to assess the frequency of tumor cells (b). All data represent arithmetic means (±SD) for each group. *^,**p < 0.02, <0.05 relative to control with no cell transfer