The primary features of Alzheimer's disease (AD) are extracellular amyloid plaques consisting mainly of deposits of amyloid beta (A beta) peptides and intracellular neurofibrillary tangles (NFTs). Sets of evidence suggest that interleukin-5 (IL-5) is involved in the pathogenesis of AD. Herein, we investigated the protective role of IL-5 in PC12 cells, to provide new insights into understanding this disease. Western blot was employed to assess the protein levels of Bax and phospho-tau as well as phospho-JAK2; MTT assay was performed to decipher cell viability. Treatment of IL-5 decreased A beta(25-35)-induced tau phosphorylation and apoptosis, effects blunted by JAK2 inhibition. IL-5 prevents A beta(25-35)-evoked tau protein hyperphosphorylation and apoptosis through JAK2 signaling.