Isolation and characterization of the potential receptor for wheat germ agglutinin from human neutrophils
Neutrophils participate in host protection and central to this process is the regulation of oxidative mechanisms. We purified by affinity chromatography the receptor for the GlcNAc-specific WGA from CD14+CD16+ cell lysates (WGAr). The receptor is a 141 kDa glycoprotein constituted by two subunits of 78 and 63 kDa. It is mainly composed of Ser, Asx, and Gly, and, in a minor proportion, His, Cys, and Pro. Its glycan portion contains GlcNAc, Gal, and Man; NeuAc and GalNAc were identified in a minor proportion. The amino acid sequence of the WGA receptor was predicted from tryptic peptides by MALDI-TOF, both subunits showed homology with cytokeratin type II (26 and 29% for the 78 and 63 kDa subunits, respectively); the 78 kDa subunit showed also homology with the human transferrin receptor (24%). Antibodies against WGAr induce higher oxidative burst than WGA, determined by NBT reduction; however, this effect was inhibited (p<0.05) with GlcNAc suggesting that WGAr participates as mediator in signal transduction in neutrophils.