Bolesatine induces agglutination of rat platelets and human erythrocytes and platelets in vitro

Bolesatine is a toxic glycoprotein isolated from the mushroom Boletus satanas Lent, which has been shown to inhibit protein synthesis in cell-free systems and cell culture. It is toxic to rodents, the LD(50)% 24 h being 1 mg kg(-1) (i.p.) and 0.15 mg kg(-1) (i.v) in the rat in which it induces hepatic blood stasis. Bolesatine possesses lectinic properties with in particular a sugar binding site for D-galactose and mitogenic activity toward lymphocytes. Tested for cell agglutination on red blood cells and platelets, bolesatine agglutinates both human and rat platelets from threshold concentrations of 30 and 300 nM respectively. EDTA and PGI(2) (aggregation inhibitors) do not decrease agglutination induced by bolesatine, indicating that the process does not involve platelet activation. In contrast, fibrinogen decreases platelet agglutination induced by bolesatine, most likely by masking the binding sites on platelets or by interacting with the toxin. Bolesatine agglutinates all red blood cells without any blood group specificity in the concentration range of 20 to 40 nM. This haemagglutination cannot be prevented by sugars, including D-galactose at a concentration of 0.5 M.