Altered distribution of some surface glycosaminoglycans and glycoconjugates on human blood platelets in diabetes mellitus.
The distribution of some proteoglycan anionic sites and carbohydrate moieties on the diabetic platelet surface has been investigated by cytochemical methods. Human blood platelets obtained from either diabetic patients (serum glycaemia 9.6-19.2 mmol/L) or normal donors were labeled with specific stains (Ruthenium Red, Safranin O) or with biotinylated lectins (WGA, RCA(120))/Straptavidin-gold. All the probes were processed in a standardised manner for transmission electron microscopy. Results showed a modified pattern of diabetic platelet surface labeling as compared to normals. The anionic sites in the glycocalyx (particularly proteoglycans), evenly distributed all over the normal platelet plasma membrane, suffered a marked redistribution, with cluster formation, on the surface of diabetic platelets. The sugar moieties were also differently exposed: as compared to normal, diabetic platelets expressed a 1.5-fold lower number of WGA-binding sites (sialic acid) and a 2.5-fold higher number of RCA(120)-binding sites (galactose residues). We conclude that the distribution of some platelet surface components, potentially implicated in the adhesion and aggregation processes, is significantly modified on platelets from diabetic patients.
Institute of Cellular Biology and Pathology, Bucharest, Romania.
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Lupu
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Rizescu
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Calb