DC vaccines but not Flt3L administration generate an anti-AML memory cell response.
(A) A cohort of Flt3L-treated mice (dose and schedule as in Figure 2) that were challenged with C1498 cells on day 0 were rechallenged with the same dose of C1498 cells (2 × 105 per mouse) on day 60. As a control, a cohort of concurrent, nonmanipulated B6 controls (n = 10) were given C1498 AML cells (2 × 105 per mouse) on the same day used for rechallenge. There was no significant difference in these groups when comparing survival rates after day 60 (day of rechallenge). (B) In a separate experiment, recipients were vaccinated with C1498-lysate–pulsed DCs (as in Figure 2) or irradiated C1498 cellular vaccines (107 cells per mouse) given on days −14 and −7 or left untreated. On day 60, mice were challenged with C1498 cells (2 × 105). Mice given AML-lysate–loaded DC vaccines or irradiated whole cellular AML vaccines 71 days earlier had a memory cell response since 40% and 50% of mice challenged with a supralethal AML cell dose (2 × 105 cells) survived long term as compared with 0% of nonvaccinated controls (P = .00055; P = .00037 vs control, respectively). There was no significant difference (P = .32) between these 2 vaccination approaches in terms of anti-AML memory responses.
