Ultrastructural demonstration of Maclura pomifera agglutinin binding sites in the membranocystic lesions of membranous lipodystrophy (Nasu-Hakola disease)

This paper reports three cases of membranous lipodystrophy (Nasu-Hakola disease) in two families and studies the carbohydrate components of membranocystic lesions in all three cases, using twelve kinds of lectins labelled by horseradish peroxidase (HRP). Maclura pomifera agglutinin (MPA), which specifically binds α-D-galactose residues, strongly stained typical membranocystic lesions, whereas the other lectins did not. However, Helix pomatia agglutinin (HPA), which specifically binds to N-acetyl-D-galactosamine (GalNAc), stained the membranes of degenerated adipose cells. These were thought to appear during the initial or early stage of the membranocystic lesions. This suggests that a change of carbohydrate residues occurs during the formation of the membranocystic lesions. We also investigated the lectin binding sites at the ultrastructural level using MPA-HRP colloidal gold (CG) conjugate. In the well developed membrane, CG particles were arranged regularly along the minute tubular structures. On the other hand, there were a few irregularly spaced CG particles on the thinner membranes and also on the membranes of the degenerating adipose cells. No CG particles labelled the cell membranes of normal adipose cells. The presence of α-D-galactose residues in the membranocystic lesions is demonstrated for the first time at the electron microscopic level.