This might have direct implication for all those clinical conditions relying on T-cell detection for diagnosis and prognosis. Furthermore, the finding that IL-7 elicits the expansion of tumour-specific T cells, in the absence of exogenous Ag provision provides a suitable alternative for all those situations for which the Ag remains to be identified. In the model system adopted in

this study, IL-7-expanded CD4+ T cells were capable of supporting the development of protective anti-tumour immunity, while IL-2 cultured cells were not. To date, GPCR Compound Library screening the clinical efficacy of ACT, although proven in recent clinical trails 1, remains limited to a fraction of the patients. This might be due to limitations imposed by current strategies Trichostatin A chemical structure used to isolate tumour-specific lymphocytes,

and insufficient CD4+ T-cell help. Indeed, present ACT strategies mostly exploit Ag in combination with IL-2-driven T-cell stimulation, which favor production of effector CD8+ T cells lacking long-term survival 36, 50. In agreement, we found that IL-2, although capable of sustaining the proliferation/accumulation of in vivo Ag-sensitized CD4+ T cells without the need of exogenous Ag provision, did not promote viability/survival and LN homing to similar extents as IL-7. Alongside with effector cytokine production (IL-2 and IFN-γ secretion), IL-7-cultured CD4+ T cells maintained a less differentiated phenotype than IL-2 cultured CD4+ T cells, allowing superior persistence and LN homing when infused in tumour-bearing hosts. We found that replenishing the cultures with IL-7 after 7 days further promoted the accumulation of tumour-specific T cells (data not shown). At present it remains to be determined whether longer cultures will also preserve the poorly differentiated state of the cells, which might be critical for the in vivo efficacy. Most recently, IL-7 was also shown to promote the ex vivo expansion of CD8+ T cells 51, 52. This together with the notion that less differentiated T-cell subsets might be more potent than fully differentiated effector cells 53, suggest that

IL-7 should be preferred Sitaxentan to IL-2 when attempting the ex vivo expansion of CD4+ and CD8+ T cells to be used in anti-tumour ACT. TS/A-LACK cells do not express MHC class II molecules, and their parental cell line TS/A relies on CD8+ T cells to be rejected 47. We speculate that IL-7-expanded cells following ACT by migrating to T-dLN and to the tumour might provide help to CD8+ T cells and other immune effectors and by that favor tumour rejection. Thus, together with the finding that IL-7 and IL-15 drives the in vitro generation of self-renewing central memory human T lymphocytes 54, our data support the use of IL-7 for the identification and the expansion of clinically relevant T-cell subsets. Eight-week-old BALB/c mice were purchased from Charles River (Charles River Italia, Milan, Italy). 16.