Presence of an alpha-galactolipid on the cell surfaces of endothelial cells of human kidney.

The presence of an alpha-galactolipid was investigated with a peroxidase-labelled lectin from Griffonia simplicifolia (GSA-I) with specific binding for terminal alpha-D-galactose residues. Normal kidney tissue was obtained from patients undergoing nephrectomy for renal neoplasms. For light microscopy, tissue was snap-frozen; 4 microns-thick sections were briefly fixed in paraformaldehyde and incubated with GSA (0.025 mg ml-1). The peroxidase activity was developed with 3-amino-9-ethylcarbazole. Adjacent sections were stained at the same time after lipid extraction with 3:1 (v/v) chloroform/methanol. For electron microscopy, 0.2-0.5 mm-thick paraformaldehyde-fixed blocks, with or without lipid extraction, were stained with peroxidase-labelled GSA. The label was developed with diaminobenzidine and osmium tetroxide. Some structures, such as tubular epithelia, stained both in lipid-extracted and non-extracted tissues, suggesting that glycoproteins were most likely involved. In addition, tissue stained immediately after fixation showed GSA reactivity on endothelial cell surfaces of intertubular capillaries and larger vessels. In lipid-extracted tissues, however, tubular epithelium was still positive for GSA but endothelial cells failed to stain. These findings suggest that a glycolipid, bearing a terminal alpha-galactose residue, is present on the endothelial cells in human kidney and possibly on tubular epithelia. Our data may explain the preferential storage of alpha-galactolipid in endothelial cells of patients with Fabry's disease and other biological phenomena such as Escherichia coli adhesion.