A new phosphoglycerolipid, 'phosphatidylglucose', found in human cord red cells by multi-reactive monoclonal anti-i cold agglutinin, mAb GL-1/GL-2.

Cord red cell membranes express many differentiation-related molecules. To study such molecules, we have established human cell lines, termed GL-1 and GL-2, by the Epstein-Barr virus transformation method, both of which produce monoclonal anti-i cold agglutinin [Y. Nagatsuka et al., Immunol. Lett. 46 (1995) 93-100]. Thin layer chromatography immunoblotting analysis revealed that these antibodies had broad specificities reacting with a variety of glycolipid antigens. Of the immunoreactive lipid antigens, a new phosphoglycerolipid containing glucose from human cord red cells was found. The isolated lipid was unstable to alkaline hydrolysis and contained glucose as a sole sugar. Secondary ion mass spectrum-collision-induced dissociation mass spectrometric analysis of this lipid gave the main molecular ion peak at m/z 885 corresponding to phosphatidylhexose. This antigen was susceptible to phospholipases A2, C and D but resistant to phosphatidylinositol-specific phospholipase C. Two-dimensional nuclear magnetic resonance spectroscopy confirmed that glucose is linked to the sn-glycerol 3-phosphate residue with a beta-anomeric configuration. Based upon these combined results, we identified this lipid as phosphatidyl-beta-D-glucose. This is the first report showing the presence of the glucosylated glycerophospholipid in mammalian sources.