Protective immunity from naive CD8(+) T cells activated in vitro with MHC class I binding immunogenic peptides and IL-2 in the absence of specializedAPCs

Ag-specific CTL can protect against tumors and some viral infections and ma y be useful for adoptive immunotherapy, Here, we show that purified CD8(+) T cells from naive C57BL/6 mice can be primed in vitro with different immun ogenic peptides, which bind to MHC class I gene products, and IL-2 to exhib it specific and MHC-restricted effector function in vitro and in vivo prote ction against lymphocytic choriomeningitis virus infection and B16.F10 mela noma lung metastases. Limiting dilution assays in the absence of feeder cel ls with highly purified CD8(+) T cells from two transgenic mice strains, ea ch expressing a different MHC class I-restricted TCR, indicated that only p eptide and IL-2, but not TCR- cells, were required for the growth of naive CD8(+) T cells. These alternative minimal requirements for the activation a nd expansion of specific CD8(+) T lymphocytes, without the need for profess ional APC, may be exploited for adoptive immunotherapy.