The core fucose on an IgG antibody is an endogenous ligand of Dectin‐1

The core fucose, a major modification of N -glycans, is implicated in immune regulation, such as the attenuation of the antibody-dependent cell-mediated cytotoxicity of antibody drugs and the inhibition of anti-tumor responses via promotion of PD-1 expression on T cells. Although the core fucose regulates many biological processes, no core fucose recognition molecule has been identified in mammals. In the present study, we discovered that Dectin-1, a known anti- b -glucan lectin, recognizes the core fucose on IgGs. A combination of biophysical experiments further suggested that Dectin-1 recognizes aromatic amino acids adjacent to the N -terminal asparagine residue at the glycosylation site as well as core fucose residue. Thus, Dectin-1 appears to be the first lectin-like molecule involved in the hetero-valent and specific recognition of characteristic N -glycans on antibodies.