Induction of cytolytic cells by pure recombinant human interleukin 2

Purified recombinant human interleukin 2, produced in Escherichia coli, was sufficient to generate cytolytic cells in concanavalin A-stimulated, T helper cell-depleted (Lyt-1.1-) or accessory cell-depleted (Ia-) murine spleen cell cultures. Moreover, recombinant interleukin 2 (rIL2) was able (even at 0.5 ng/ml) to induce cytolytic cells in undepleted murine spleen cell cultures and undepleted human peripheral blood lymphocyte cultures in the absence of a mitogen. Purified recombinant human interferon-gamma, produced in Chinese hamster ovary cells, did not induce either cytolytic activity or IL2 responsiveness in human peripheral blood lymphocyte cultures. Possibly, the rIL2-induced cytolytic cells are formed as a result of nonspecific secondary cytotoxic T lymphocyte activation.