IL25 (Interleukin-25), also known as IL17E, is reported to induce NF-κB activation, and stimulate the production of IL-8. Besides, this cytokine shares the sequence similarity with IL17, which is considered as a ligand for IL17RA. Thus, a binding ELISA assay was conducted to detect the association of recombinant human IL25 with IL17RA. Briefly, IL25 were diluted serially in PBS with 0.1%BSA (pH 7.4). Duplicate samples of 100uL were then transferred to IL17RA-coated microtiter wells and incubated for 2h at 37°C. Wells were washed with PBST and incubated for 1h with anti-IL25 pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody, wells were aspirated and washed 3 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37°C. Finally, add 50μL stop solution to the wells and read at 450nm immediately. The binding activity of IL25 with IL17RA was shown in Figure 1 and this effect was in a dose dependent manner.