(A) Jurkat cells cultured in RPMI-1640, stimulated with 1ng/mL IL15 72h; (B) Unstimulated Jurkat cells cultured in RPMI-1640 for 72h.

Interleukin 15 (IL15) is a widely expressed cytokine that is structurally and functionally related to IL2, which plays an important role in many immunological diseases. IL15 also regulates T and natural killer (NK) cell activation and proliferation. To test the effect of IL15 on cells proliferation of human T lymph°Cyte cells, Jurkat cells were seeded into triplicate wells of 96-well plates at a density of 10, 000 cells/well in RPMI-1640 with the addition of various concentrations of IL15. After incubated for 72h, cells were observed by inverted microscope and cell proliferation was measured by Cell Counting Kit-8 (CCK-8). Briefly, 10µL of CCK-8 solution was added to each well of the plate, then the absorbance at 450nm was measured using a microplate reader after incubating the plate for 1-4 hours at 37°C. Cell proliferation of Jurkat cells after incubation with IL15 for 72h observed by inverted microscope was shown in Figure 1. The dose-effect curve of IL15 was shown in Figure 2. It was obvious that IL15 significantly promoted cell proliferation of Jurkat cells. The ED50 for this effect is typically 0.7240 to 5.206ng/mL.