Analysis of cell surface glycoconjugates in fibroblasts from patients with cystic fibrosis

Abstract

Although the basic biochemical defect in cystic fibrosis (CF) is unknown, previous studies have indicated that errors in protein glycosylation may be involved in the pathogenesis of the disease. Utilizing human skin fibroblasts, the present study was designed to quantitatively analyze glycosylation of cell surface glycoconjugates in CF and normal cells. Cell surface glycoconjugates were analyzed using 125I-concanavilin A (Con A), 125I-WGA, and Con A-ferritin conjugates. Under our binding conditions, Con A was used as a probe for mannose residues and WGA was used as a probe for N-acetylglucosamine residues. Saturable binding of both probes was observed and appropriate sugar controls confirmed the specificity of each lectin. When compared on a DNA basis, iodinated lectin binding studies indicated that no consistent differences existed between CF and normal strains of human skin fibroblasts. Ultrastructural quantitative morphometric analysis of Con A-ferritin conjugate binding indicated that neither proteolysis of cell surface glycoconjugates or internalization of lectin probes was occurring at saturable binding concentrations. In summary, our results indicated that no consistent differences in cell surface mannose and N-acetylglucosamine residues could be detected between the normal and CF strains of human skin fibroblasts used in these studies.