Results obtained from 2 independent experiments were pooled. Statistical test: Mann–Whitney; NS: not significant. We next addressed the question of whether

CpG motifs have the same antitumor effect in cerebral lymphomas. Imaging analysis showed two different profiles. Some mice did not respond to in situ CpG-ODN treatment, and the lymphoma developed in the brain and even developed in lymph nodes at day 21; this timing was nonetheless later than in the control group (Figure 2C – Example 1). Some mice did respond to the treatment; the tumor grew from day 0 to day 7 after treatment, and then decreased until it was undetectable (Figure 2C click here – Example 2). We also examined the percentage of CD19+GFP+ cells in the group treated by CpG-ODNs, compared it with the control group and observed a significant

decrease in the proportion of tumor cells (Figure 2D). Next we investigated the antitumor effect of CpG-ODNs on PIOL mice that had a tumor implanted in the right eye only and were then treated with CpG-ODNs (20 μg/2μL) or control ODNs (20 μg/μL). As shown in Figure 2E, CpG-ODNs seem to have had no detectable see more effects on the primary eye tumor. Nevertheless, they appeared to prevent lymph node invasion at day 27 (Figure 2E). Flow cytometric analysis showed no significant difference in tumor growth between CpG ODN-treated and control (PBS 1X) treated eyes (Figure 2F). These results suggest that the behavior of tumors in the eye is different from that of systemic lymphomas, but also from that of cerebral lymphoma, and thus, that tumor cells responsiveness to Go6983 CpG-DNA depend on the tissue microenvironment. Soluble molecules from the PIOL microenvironment counteract the antiproliferative

effect of CpG-ODNs on malignant Baf-A1 B-cells in a dose-dependent-manner As described above, in vivo experiments showed that the responsiveness of lymphoma B cells to CpG-ODN administration was tissue-dependent. To confirm that the blockade of CpG-ODN antitumor effects was due to the PIOL molecular microenvironment, we tested whether supernatant from PIOL could counteract the inhibitory effect of CpG-ODNs on the proliferation of A20.IIA cells in vitro. A [3H] thymidine incorporation assay was performed as described above, with the addition of supernatant obtained from PBS-injected eyes (PIE) (as control), or from the mouse model SCL, PCL, and PIOL. As shown in Figure 3, the addition of PIE (Figure 3A) and SCL (Figure 3B) supernatants did not modify the ability of CpG-ODN treatment to inhibit tumor growth. PCL supernatant (Figure 3C) increased proliferation, but CpG-ODNs were still active at doses of 30 and 60 μg/mL. In contrast, CpG-ODNs were unable to inhibit tumor cell proliferation after incubation with PIOL supernatant (Figure 3D) and to induce apoptosis (data not shown).