ALTERED DISTRIBUTION OF SOME SURFACE GLYCOSAMINOGLYCANS AND GLYCOCONJUGATES ON HUMAN BLOOD-PLATELETS IN DIABETES-MELLITUS

The distribution of some proteoglycan anionic sites and carbohydrate m oieties on the diabetic platelet surface has been investigated by cyto chemical methods. Human blood platelets obtained from either diabetic patients (serum glycaemia 9.6-19.2 mmol/L) or normal donors were label ed with specific stains (Ruthenium Red, Safranin 0) or with biotinylat ed lectins (WGA, RCA120)/Straptavidin-gold. All the probes were proces sed in a standardised manner for transmission electron microscopy. Res ults showed a modified pattern of diabetic platelet surface labeling a s compared to normals. The anionic sites in the glycocalyx (particular ly proteoglycans), evenly distributed all over the normal platelet pla sma membrane, suffered a marked redistribution, with cluster formation , on the surface of diabetic platelets. The sugar moieties were also d ifferently exposed: as compared to normal, diabetic platelets expresse d a 1.5-fold lower number of WGA-binding sites (sialic acid) and a 2.5 -fold higher number of RCA120-binding sites (galactose residues). We c onclude that the distribution of some platelet surface components, pot entially implicated in the adhesion and aggregation processes, is sign ificantly modified on platelets from diabetic patients.