Serum Amyloid A2 (SAA2) is a multifunctional apolipoprotein that belongs to SAA family. SAA2 is produced by hepatocytes in response to pro-inflammatory cytokines and is the most prominent members of the acute phase response (APR) during which their serum levels rise dramatically after trauma, infection and other stimuli. Besides, Apolipoprotein C3 (APOC3) has been identified as an interactor of SAA2, thus a functional binding ELISA assay was conducted to detect the interaction of recombinant human SAA2 and recombinant human APOC3. Briefly, SAA2 were diluted serially in PBS, with 0.01% BSA (pH 7.4). Duplicate samples of 100 ul were then transferred to APOC3-coated microtiter wells and incubated for 2h at 37℃. Wells were washed with PBST and incubated for 1h with anti-SAA2 pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody, 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 recombinant human SAA2 and recombinant human APOC3 was shown in Figure 1, and this effect was in a dose dependent manner.