Macrophage Inflammatory Protein 1 Beta (MIP1b), also known as CCL4, is a cytokine belonging to the CC chemokine family that is secreted at sites of inflammation by activated leukocytes, lymphocytes, vascular endothelial cells, and pulmonary smooth muscle cells. As a chemokine, MIP1b binds to the G-protein-coupled receptors CCR5 and CCR8, acting as a chemical attractant for natural killer cells, monocytes, and various other immune cells at sites of inflected or damaged tissue. At the same time, MIP1b can also retain the abilities to induce down-modulation of surface expression of the chemokine receptor CCR5 and to inhibit the CCR5-mediated entry of HIV-1 in T-cells. Chemokine C-C-Motif Receptor 7 (CCR7) can interact with MIP1b.Thus a functional binding ELISA assay was conducted to detect the interaction of recombinant human MIP1b and recombinant mouse CCR7. Briefly, biotin-linked MIP1b were diluted serially in PBS, with 0.01% BSA (pH 7.4). Duplicate samples of 100 ul were then transferred to CCR7-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 450/630 nm immediately. The binding activity of recombinant human MIP1b and recombinant mouse CCR7 was shown in Figure 1, the EC50 for this effect is 1.17 ug/mL.