Fc receptor with low affinity for IgG (Fc gamma RIII, CD16) is encoded by two nearly identical genes, Fc gamma RIII-A and Fc gamma RIII-B, resulting in tissue-specific expression of alternative membrane-anchored isoforms. FcgR3A is expressed in almost all white blood cells and is primarily responsible for the ADCC action of NK cells and the clearance of antibody-antigen immune complexes by macrophages. FcgR3B is mainly expressed in neutrophils and can stimulate the release of superoxide in neutrophils. A functional binding ELISA assay was conducted to detect the interaction of recombinant mouse FcgR3A and mouse IgG. Briefly, biotin-linked FcgR3A were diluted serially in PBS, with 0.01% BSA (pH 7.4). Duplicate samples of 100 ul were then transferred to IgG-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 nm immediately. The binding activity of recombinant mouse FcgR3A and mouse IgG was shown in Figure 1, the EC50 for this effect is 0.26 ug/mL.