Interleukin 7 Receptor (IL7R), also known as CD127, is a 75 kDa hematopoietin receptor superfamily member that plays an important role in lymphocyte differentiation, proliferation and survival. Besides, IL7R?is involved in the pathogenesis of neurodegenerative disorders, such as multiple sclerosis. Thymic Stromal Lymphopoietin (TSLP) has been identified as an interactor of IL7R, thus a functional binding ELISA assay was conducted to detect the interaction of recombinant human IL7R and recombinant human TSLP. Briefly, biotin-linked IL7R were diluted serially in PBS, with 0.01% BSA (pH 7.4). Duplicate samples of 100 ul were then transferred to TSLP-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST 3 times and incubation with Streptavidin-HRP for 30min, then wells were aspirated and washed 5 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37℃. Finally, add 50 μl stop solution to the wells and read at 450 nm immediately. The binding activity of IL7R and TSLP was shown in Figure 1, the EC50?for this effect is 0.956 ug/mL.