Peptidoglycan Recognition Protein 1 (PGLYRP1) is a member of a family of proteins that recognize and bind to peptidoglycan, a major component of bacterial cell walls. PGLYRP1 helps defend against bacterial infections by recognizing peptidoglycans and participating in the host's immune response. It plays an important role in the immune system, activating immune cells, promoting inflammatory responses, and directly destroying bacterial cell walls. Besides, Lactoferrin (LTF) has been identified as an interactor of PGLYRP1, thus a functional binding ELISA assay was conducted to detect the interaction of recombinant human PGLYRP1 and recombinant human LTF. Briefly, PGLYRP1 was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to LTF-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-PGLYRP1 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 450/630 nm immediately. The binding activity of recombinant human PGLYRP1 and recombinant human LTF was shown in Figure 1, the EC50?for this effect is 0.61 ug/mL.