To clarify the role of Ctenopharyngodon idella allograft inflammatory factor-1 (AIF-1) in host immune response, AIF-1 expression profile in peripheral blood leukocytes was investigated with lipopolysaccharide exposure using western blot. Then, the effect of AIF-1 on cell viability was assayed with a CCK-8 kit, cell apoptosis was detected by flow cytometer, ATP production, mitochondrial membrane potential, reactive oxygen species and nitric oxide were determined with the corresponding kit. Finally, the levels of inflammatory cytokine tumor necrosis factor-alpha (TNF-α), interleukin 1β (IL1β), interleukin 6 (IL6) were measured using ELISA kits. The results shown that lipopolysaccharide stimulated AIF-1 secretion from leukocytes. Furthermore, C. idella AIF-1 induced leukocyte proliferation, and increased mitochondrial membrane potential, subsequently promoted ATP production, prevented leukocyte apoptosis. In addition, it provoked inflammatory mediator reactive oxygen species, nitric oxide, inflammatory cytokine TNF-α, IL1β, IL6 released from leukocytes. These results indicated AIF-1 was a potential stimulator for leukocyte viability and associated with C. idella immune response.