Interleukin-2 (IL-2) is an interleukin, a type of cytokine signaling molecule in the immune system. IL-2 has essential roles in key functions of the immune system, tolerance and immunity, primarily via its direct effects on T cells. In the thymus, where T cells mature, it prevents autoimmune diseases by promoting the differentiation of certain immature T cells into regulatory T cells, which suppress other T cells that are otherwise primed to attack normal healthy cells in the body. IL-2 also promotes the differentiation of T cells into effector T cells and into memory T cells when the initial T cell is also stimulated by an antigen, thus helping the body fight off infections. To measure the effect of IL-2 on cell proliferation, CTLL-2 cells were seeded into triplicate wells of 96-well plates at a density of 2,000 cells/well with 2% serum standard 1640 contain various concentrations of recombinant human IL-2. After incubated for 96h, 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℃. Proliferation of CTLL-2 cells after incubation with IL-2 for 96h observed by inverted microscope was shown in Figure 1. Cell viability was assessed by CCK-8 assay after incubation with recombinant IL-2 for 96h. The result was shown in Figure 1. It was obvious that IL-2 significantly increased cell viability of CTLL-2 cells.
(A) CTLL-2 cells cultured in 1640, stimulated with 10ng/mL IL-2 for 96h;
(B) Unstimulated CTLL-2 cells cultured in 1640 for 96h.
Figure. Cell proliferation of CTLL-2 cells after stimulated with IL-2.

Figure. Cell proliferation of CTLL-2 cells after stimulated with IL-2.