Contrasting effects of interleukin-2 secretion by rat glioma cells contingent upon anatomical location: accelerated tumorigenesis in the central nervous system and complete rejection in the periphery.

Rat T9.F glioma cells were transduced with the interleukin (IL)-2 gene. Clone T9.F/IL2/#12 secreted a high level of IL-2 (15 ng/10(6) cells/48 h). Enhanced tumor progression and reduced survival was observed when T9.F/IL2/#12 cells were implanted intracranially. Subcutaneous injection of T9.F/IL2/#12 cells induced a palpable nodule, which regressed in approximately 15 days, resulting in tumor-specific protection. Lymphocytes from T9.F/IL2/#12 primed rats specifically respond to T9.F antigens but lacked cytotoxicity towards T9.F cells. Intracranial T9.F/IL2/#12 tumors were markedly infiltrated by CD4(+) and CD8(+) T cells, natural killer (NK)-T cells and myeloid progenitor cells, whereas subcutaneous T9.F/IL2/#12 tumors contained an elevated level of NK cells.