IL2 and neoplasm: To establish if systemic immunological memory responses to tumour cells had been established, tumour-free mice (n=7 from Neuro-IL2/IL12 and n=9 from AJ-IL2/IL12 groups) were rechallenged 3 months after the initial vaccine with 106 wild-type Neuro-2A cells in the opposite flank to the original injection, with no further vaccination.