Interleukin 10 (IL-10), also known as human cytokine synthesis inhibitory factor (CSIF), is an anti-inflammatory cytokine. IL-10 is a cytokine with multiple, pleiotropic, effects in immunoregulation and inflammation. It downregulates the expression of Th1 cytokines, MHC class II antigens, and co-stimulatory molecules on macrophages. It also enhances B cell survival, proliferation, and antibody production. IL-10 can bl°Ck NF-κB activity, and is involved in the regulation of the JAK-STAT signaling pathway. Besides, Interleukin 10 Receptor Alpha (IL10Ra) has been identified as an interactor of IL-10, thus a binding ELISA assay was conducted to detect the interaction of recombinant mouse IL-10 and recombinant mouse IL10Ra. Briefly, IL-10 were diluted serially in PBS, with 0.01% BSA (pH 7.4). Duplicate samples of 100μL were then transferred to IL10Ra-coated microtiter wells and incubated for 2h at 37°C. Wells were washed with PBST and incubated for 1h with anti-IL-10 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 IL-10 and IL10Ra was shown in Figure 1, and this effect was in a dose dependent manner.