Interferon-alpha (IFN-α), also known as leukocyte interferon, represents a group of related but distinct proteins that share over 95% amino acid sequence homology. They are members of the type I interferon family which share a common cell surface receptor composed of two subunits. IFN-α has both anti-viral and immunomodulatory activities on target cells. To test the effect of IFN-α on cell apoptosis, A549 cells were seeded into 96-well plates at a density of 3,000 cells/well with 1% serum standard DMEM including various concentrations of recombinant human IFN-α. After incubated for 48h, cells were observed by inverted microscope and cell proliferation was measured by Cell Counting Kit-8 (CCK-8). Briefly, 10 µL of CCK-8 solution was added to each well of the plate, then the absorbance at 450 nm was measured using a microplate reader after incubating the plate for 2 hours at 37℃. Proliferation of A549 cells after incubation with IFN-α for 48h observed by inverted microscope was shown in Figure 1. Cell viability was assessed by CCK-8 (Cell Counting Kit-8 ) assay after incubation with recombinant human IFN-α for 48h. The result was shown in Figure 2. It was obvious that IFN-α significantly inhibit cell viability of A549 cells. The ED50 is 3.4 µg/mL.
(A) A549 cells cultured in DMEM, stimulated with 10µg/mL IFN-α for 48h;
(B) Unstimulated A549 cells cultured in DMEM for 48h.
Figure 1. Inhibition of A549 cells proliferation after stimulated with IFN-α

Figure 2. Inhibition of A549 cells proliferation after stimulated with IFN-α.