A study of platelet fibronectin immunofluorescence in peripheral vascular disease and diabetes mellitus.

Platelets hyperaggregability and hypersecretion fibronectin (Fn) are known to occur in peripheral vascular disease (PVD) and diabetes mellitus (DM) with microangiopathy. To determine whether an increase in platelet membrane bound Fn constitutes to hyperaggregability of platelets, washed platelets from normal subjects and from patients with peripheral vascular disease and patients with diabetes mellitus were examined for the presence of fibronectin (Fn) by means of fluorescein linked antibody to Fn. Platelets from peripheral vascular disease and diabetes mellitus patients tended to aggregate during preparation and apparently exhibited greater fluorescence in platelet "smears" than was observed in smears from controls. In contrast, when washed platelet "smears" were prepared from platelet preparations containing iloprost, an analogue of prostacyclin, platelet aggregates did not form and the 'excess' of fluorescence disappeared from all the three groups. When platelets were stained for Fn fluorescence in suspensions, no fluorescence was observed on the surface of platelets from peripheral vascular disease and diabetes mellitus patients or controls. On stimulation with thrombin washed platelet suspension showed fluorescence for Fn. Platelet activation leads to Fn appearing on platelet surface but this effect cannot be quantified by optical fluorescence microscopy.