CpG 2006 treatment prolongs the survival of syngenic BMT recipients challenged with AML cells 2.5 months after BMT but does not induce a memory cell response.
Lethally irradiated B6 recipients were reconstituted with B6 bone marrow cells (n = 10 per group). Cohorts of mice, as indicated, received CpG 1585 or 2006 ODNs beginning on day 64 and continuing through day 90 (CpG 1585) or day 92 (CpG 2006) after BMT. A separate cohort received irradiated tumor vaccines (termed C1498x) given subcutaneously on days 66 and 73 after BMT. Mice were challenged with C1498 (105/mouse) or, as indicated, no C1498 cells or C1498 (104/mouse). All surviving mice in the indicated groups were challenged with C1498 cells (105/mouse) on day 219 after BMT to assess memory cell response. (A) Although CpG 1585-treated recipients did not protect mice against C1498 challenge (P = .21 versus control), CpG 2006 was effective (P = .00053 versus control), resulting in more than a 10-fold reduction in tumorigenicity when comparing outcome to recipients of C1498 at a dose of 104 cells/mouse (P = .00074). (B) C1498x but not CpG 2006 induced a memory cell response as compared with control BMT recipients not previously challenged with C1498 cells (P = .00015 and .46, respectively).
