Transduction of an IL-2 gene into human melanoma-reactive lymphocytes results in their continued growth in the absence of exogenous IL-2 and maintenance of specific antitumor activity

IL-2-dependent activated cells undergo apoptotic death when IL-2 is withdrawn either in vitro or after in vivo cell transfer. To attempt to sustain their survival after IL-2 withdrawal, melanoma reactive human T lymphocytes were retrovirally transduced with an exogenous human IL-2 gene. Transduced PBMC and cloned CD8(+) T cells produced IL-2 and maintained viability after IL-2 withdrawal. Upon restimulation, IL-2 transductants proliferated in the absence of exogenous IL-2 and could be actively grown, and their survival could be maintained without added IL-2 for over 8 wk. PBMCs similarly transduced with a control vector did not produce IL-2 and failed to proliferate in the absence of IL-2. A CD8(+) T cell clone, when transduced with an IL-2 gene, manifested the same phenotypes as PBMCs in the absence of exogenous IL-2. Furthermore, an Ab reactive with the alpha -chain of IL-2R complex reduced the viability mediated by IL-2 secretion of the IL-2 transductants. Moreover, transduction of an IL-2 gene did not affect the high degree of recognition and specificity of transductants against melanoma targets. These tumor-reactive IL-2 transductants may be valuable for in vitro studies and for improved adoptive transfer therapies for patients with metastatic melanoma.