Abstract
The effects of recombinant interleukin 2 (re-IL2) and interferonγ (re-IFNγ) on the natural killer (NK) cell activity were studied, special cares being paid to elucidate the interrelationship between these lymphokines. Peripheral blood lymphocytes from normal volunteers and gastrointestinal cancer patients were obtained by Ficoll-Urografin sedimentation. Augmentation of NK cell activity was induced after incubating the cells with various doses of re-IL2 or re-IFNγ for 18 hours. NK cell activity was measured by the 4.5hr 51Cr-release assay using K-562 cells as a target. The NK cell activity from both normal donors and cancer patients was greatly enhanced by re-IL2. This augmentation of NK cell activity by re-IL2 was dose dependent and even as small dose as 10u/ml of re-IL2 was able to augment NK cell activity significantly. On the other hand, augmentation of NK cell activity by re-IFNγ (range-8.8 to 19.6% at 1, 000u/ml) was much less, although significant, than that induced by re-IL2 (19.1 to 65.7% at 100u/ml). These results indicate that re-IL2 much more effective than re-IFNγ in the augmentation of NK cell activity in vitro. No significant differences were observed in the augmentation ratios of NK cell activity by either re-IL2 or re-IFNγ among the different cancer stages. Although re-IL2 could augment NK cell activity regardless the donors conditions, healthy or cancerous, it did not necessarily always induce IFNγ activity. Hence, we speculate that re-IL2 might work directly on NK cells without mediating IFNγ induction.
