DIFFERENCES IN MONOSACCHARIDE COMPOSITION OF MEMBRANE GLYCOPEPTIDES FROM CYSTIC FIBROSIS AND CONTROL SKIN FIBROBLASTS

Abstract

Many of the abnormal secretory products found in cystic fibrosis (CF) can result from a defect in the cell surface membrane. Consequently, the monosaccharide units from the skin fibroblasts of four patients with CF and four age, sex and race matched controls were compared. The cells, grown under the same conditions, were removed from the monolayer by controlled trypsinization. The trypsin-sensitive glycopeptides and the cells from which the glycopeptides were removed were further processed and subjected to acid hydrolysis. The resulting monosaccharides were analyzed as their alditol acetate derivatives by gas liquid chromatography. Sialic acid content was measured separately by the thio-barbituric acid assay after mild acid hydrolysis and purification on Dowex 1-X8. The molar ratios of the monosaccharide units in the CF trypsin-sensitive glycopeptide fractions from the cell surface were different from those found in the controls. Specifically, the molar ratios of fucose: sialic acid: galactose: mannose: glucosamine were 1:3:4:2:10 for the CF fractions and 1:4:7:5:14 for the controls. Similar, although less pronounced, differences were found in the whole cell fractions. Thus, a refined analysis of the monosaccharide units reveals an alteration in the complex carbohydrates of the CF fibroblast cell surface when compared to controls. USPHS grants AM16859 and GM07025.

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