Characterization of murine MGL1 and MGL2 C-type lectins: distinct glycan specificities and tumor binding properties.

Antigen presenting cells (APC) express a variety of pattern recognition receptors, including the C-type lectin receptors (CLR) that specifically recognize carbohydrate structures expressed on self-tissue and pathogens. The CLR play an important role in antigen uptake and presentation and have been shown to mediate cellular interactions. The ligand specificity of the human macrophage galactose-type lectin (MGL) has been characterized extensively. Here, we set out to determine the glycan specificity of the murine homologues, MGL1 and MGL2, using a glycan array. Murine MGL1 was found to be highly specific for Lewis X and Lewis A structures, whereas mMGL2, more similar to the human MGL, recognized N-acetylgalactosamine (GalNAc) and galactose, including the O-linked Tn-antigen, TF-antigen and core 2. The generation of MGL1 and MGL2-Fc proteins allowed us to identify ligands in lymph nodes, and MGL1-Fc additionally recognized high endothelial venules. Strikingly, MGL2 interacted strongly to adenocarcinoma cells, suggesting a potential role in tumor immunity.