Defensin Alpha 6, Paneth Cell Specific (DEFa6) is a member of the alpha defensin family , whose members are primarily involved in the host's immune response. The DEFa6 protein plays a role in the defense mechanisms of the skin and mucous membranes, especially in fighting bacterial and fungal infections. It helps defend against invasion by pathogens by forming antimicrobial peptides that destroy the cell membranes of microorganisms.Besides,Defensin Alpha 5, Paneth Cell Specific (DEFa5) has been identified as an interactor of DEFa6, thus a functional binding ELISA assay was conducted to detect the interaction of recombinant human DEFa6 and recombinant human DEFa5. Briefly, DEFa6 was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to DEFa5-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-DEFa6 pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody for 1h at 37℃, 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 450/630nm immediately. The binding activity of recombinant rat DEFa6 and recombinant human DEFa5 was shown in Figure 1, the EC50?for this effect is 0.039ug/mL.